Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. Napa County Master Gardeners (http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. You can also find us on Facebook under UC Master Gardeners of Napa County.
What to do if recent rains flooded your vegetable garden
UC Master Gardeners of Napa County
By David Layland
It seems like it was just yesterday when gardeners were looking for ways to deal with drought. We were focused on things like water conservation, planting just enough vegetables to satisfy our basic needs or maybe even skipping growing pickling cukes for our famous dills.
The good news is we have had a considerable amount of rain so far this year so it looks like we can take drought out of our gardening vocabulary for 2017. The bad news is we have had so much rain that many areas have experienced flooding. If your vegetable garden flooded then there are new potential problems to focus on.
Flooding, according to research done by North Carolina State University, can introduce pathogens to your garden; including E. coli, Salmonella, Hepatitis A and norovirus.
“Food-borne illness can affect anyone, but some groups including the very young, the very old, and those with weakened immune systems, are at greater risk and can suffer serious lifelong complications and even death. Unfortunately, some forms of these pathogens are very aggressive and can cause severe illness, even in healthy young adults.” states the “Food Safety Tips for Your Edible Home Garden” publication from the University of California at Davis.
How concerned gardeners have to be about using garden produce after a flood depends, to a large degree, on how “clean” the flood water was or whether it was likely to have been contaminated with sewage, river or creek water, farm run-off, or industrial pollutants. If you or your neighbors have livestock then your garden could be subject to farm run-off. If you have a pet area or compost pile near the flooded area then your flood water could be contaminated. The most conservative answer is that gardeners should discard all produce that was touched by flood water. However, if your garden was flooded with relatively clean flood water and the flooding occurred early, there will typically be weeks left in the growing season, and gardeners will likely be able to salvage some crops. The following are tips for what can be salvaged and what must be discarded.
Produce can be cooked to ensure safety. This is the best choice if anything that was touched by flood water will be served to those most at risk for serious consequences from microbial food-borne illnesses: young children, the elderly, pregnant women and those with compromised immune systems. Note that cooking will not eliminate the risk posed by industrial pollutants.
Discard all produce that is normally consumed uncooked (raw), including all leafy vegetables such as lettuce or spinach, regardless of how mature the plants are. It is not possible to clean these crops as they have many ridges and crevices that could contain contaminated silt or bacteria. Fruits that are ready to harvest, such as strawberries or raspberries, should also be discarded unless they can be cooked as they too are impossible to thoroughly clean and cannot be safely consumed raw.
Underground vegetables such as beets, carrots and potatoes that are still early in their growth (at least four to eight weeks from harvest) should be safe if allowed to grow to maturity. Beets may be peeled after cooking, if desired.
Now that you have assessed the possible damage to your vegetable garden and whatever is growing, there are a few more things to keep in mind.
Don’t work wet soil. Working wet soil can do long term damage to the soil structure itself. Soil particles can become compressed, increasing compaction and exacerbating drainage issues in the future. This damage is not easily or quickly repaired. Allow the soil to dry out for several days. Push a trowel into the soil and wiggle it back and forth. If visible water is in the hole, or if the soil at the sides of the trowel looks glossy, wait a few more days. When you do start working, use hand tools such as a spading fork. Tilling with an implement has more risk of compaction than lightly cultivating with a fork. If you must till, save it for drier days ahead.
Don’t rush to replant. Soil biology is damaged when soils are water-logged for long periods of time. Soil microbes that require oxygen to live may die off and those that survive without oxygen may flourish. These anaerobic microbes cause soggy soil to have that foul, sour odor.
This imbalance affects the availability of nutrients for plant use. The soil food web needs a chance to recover. This can happen relatively quickly if the soil was healthy before the storm. If sufficient organic matter, nutrients and minerals are present, beneficial soil biology will re-establish itself once oxygen is available again. If you must replant quickly in the vegetable garden, support the soil biology with added compost, dried molasses, and perhaps added mychorrhizae. Many seeds will have a tendency to rot in soggy soils. Even though you want to re-establish your veggies or plant new crops, you should wait until a ball of soil can be squeezed in your hand and no water drops can be wrung out. Like a damp sponge, moist but not wet.
Replace nutrients. Heavy rainfall can leach nutrients out of the soil. A light fertilization will replace those nutrients. Don’t overdo it. It is better to fertilize lightly several times than to push plants that are recovering from stress. Foliar feeding with a seaweed extract can quickly boost needed minerals to reduce plant stress. Use only slow-release, organic fertilizers that provide micronutrients and minerals in addition to the macro-nutrients, N-P-K. Epsom salts provide essential nutrients, magnesium and sulfur. In addition to aiding the uptake of other nutrients, these can help reduce plant stress. Broadcast over the new seedbed at a rate of 1 cup per 100 square feet.
Eliminate possible slug or snail hiding places. Slugs and snails love damp places that have hiding areas. Remove any boards, stones, or other items that are laying around in or around the garden.
Keep an eye on emerging weeds. Weeds love to pop up soon after a storm. The sudden charge of moisture to the soil will encourage weeds to spring up almost overnight. Put down some type of mulch to prevent weeds and to help ease soil erosion.
Empty any containers that have collected water. Overturn any buckets, wheelbarrows, or pot saucers that contain rainwater. These are breeding grounds for mosquitoes. If you have a rain barrel, you could dump the rainwater in there.
Keep an eye out for fungal or bacterial diseases. Damp, humid conditions are perfect for fungal and bacterial disease development. Diseases, such as powdery mildew, will spread very quickly in these conditions. Treat these diseases as soon as they are noticed. Waiting too long to act can mean serious trouble for your vegetable plants.
Yes, it’s great that drought is out of our vocabulary at least for now but too much of a good thing brings with it new challenges.
It’s Bare-Root Season
UC Master Gardeners of Napa County
By David Layland
This is a dangerous time of year for gardeners to venture into a nursery for they will see an abundant selection of beautiful bare-root fruit and nut trees. A variety of apple, peach, pear, fig, plum, walnut and almond trees are just a few of the trees you’ll find available.
While fruit trees can be planted any time of the year, the bare-root season (December to February or March) is the best for price and selection. You will also have the benefits of roots adapting quickly in un-amended native soil and the opportunity to begin to train a young tree to be the size and shape you desire.
There are some important things to consider when purchasing bare-root fruit trees.
Before purchasing a tree it’s a good idea to select an appropriate planting site and properly prepare it. Choose a site with plenty of sun. Fruit trees need at least 6 hours of sunlight per day; if a tree does not receive enough light, it will grow more slowly and set less fruit (plus, fruit that does set may be smaller and less sweet). Fruit trees also thrive in deep, well-drained soil. If soil is compacted, an area several feet wide around the planting site should be cultivated deeply to loosen the soil for root growth. Avoid adding fertilizer or soil amendments directly to the planting hole; instead, a well-decomposed compost can be worked into the planting site before digging the hole. Finally, if hardpan is present within one and one-half to two feet below the soil surface, it must be penetrated to allow proper drainage and root growth.
Check out the “chill factor.” Fruit and nut trees require a certain number of hours of temperatures below 45 degrees from November through February to successfully break dormancy and produce good fruit. In Napa, cold years have brought as many as 1,200 chill hours to as few as 600 chill hours in warm years. In our area, fruits such as apple, apricot, cherry, peach, plum, and prune are safe choices.
Choose a tree with a trunk diameter between one-half and five-eighths of an inch. Trees this size usually become established faster than larger or smaller stock. If the root mass is visible, be sure it is well balanced, not “one-sided.” Remove any dead or damaged roots before planting. It is best to plant bare-root trees immediately after bringing them home, but if this is not possible, the roots should be covered with sawdust or compost and kept moist until planting.
To prevent the tree from settling too low in the ground, dig the planting hole no deeper than the tree’s roots. To encourage root growth, the hole should be about twice as wide as the spread of the roots. If the soil contains a large amount of clay, the sides of the hole should be scored to aid outward root growth. Build a cone of soil in the center of the hole and spread the roots over the cone, with the bud union (where the tree was grafted onto the root stock) facing south west. This prevents sun-scald of the flat side of the trunk just above the bud union. Next, back-fill the hole with the same soil that was taken from it until the hole is half filled and gently firm the soil to eliminate large air pockets. Double check the planting depth, making sure the bud union is four to six inches above the soil surface. Finish filling the hole with the native soil and gently firm it once again. When properly planted, the tree’s uppermost roots should be just slightly below the soil surface and the soil should slope gently away from the trunk, preventing water from accumulating there.
After planting, remove the top of the tree by pruning back to a single trunk approximately 24 inches tall, water deeply, then mulch around your tree, avoiding the trunk. Protect it from sunburn and pests by painting the trunk with a half-and-half mixture of interior white latex paint and water.
There is no better time of year to plant a fruit tree than now. This is the dormant season and bare-root trees are just sitting at nurseries waiting to someone to give them a nice home.
Winter Gardening Do’s and Don’ts
UC Master Gardeners of Napa County
By David Layland
“Let us be grateful to the people who make us happy; they are the charming gardeners who make our souls blossom.” Marcel Proust
This year I’m grateful for what looks like a strong, early start to the rainy season. So far our rain gauge has measured 5.7″ of rainfall. Last year for the same period total rainfall was 1.4″ at our home near the intersection of Old Sonoma Road and Congress Valley Road. Let’s keep our fingers crossed for above-average rainfall to help alleviate our drought.
Any amount of rainfall is appreciated but it brings with it a need to defer some work in the garden. Stay off of wet soil as much as possible to prevent compaction. During the rainy season don’t try to work soil that is too wet. If you’re like me and you’re soil is primarily clay you don’t want to disrupt it while it is wet. One of the biggest mistakes gardeners make is trying to “work” (till up, cultivate or hoe) their high clay content garden soil before it is dry enough to be worked. When you do this, the soil structure is broken down and you end up with rock-hard crusts or clumps when the soil dries. By the time spring arrives, clay beds can be swelled with water and free clay particles float to the top and bond with each other. As the clay dries out further, a hard crust forms, which eventually starts cracking. This can happen even if there is a lot of compost or organic matter in the soil.
What you can do with your clay soil at this time of year is start preparing it for spring planting. Now is a good time add compost by layering it on top of garden beds so that in addition to improving the soil it will also protect the soil from rain and erosion.
I can’t plant anything in my clay soil right now but I can plant a few things in my raised beds. The soil in these beds doesn’t contain any clay so it dries out quickly enough after any rainfall to allow me to work the soil. Now is a good time to plant fava beans, garlic and shallot cloves, onions, radishes, parsley, spinach and kale.
You can also do some dreaming and planning with seed catalogs. If you grow your own seedlings, December and January are a great time to place your orders, enabling you to start your seeds indoors prior to the arrival of spring. Plan for frost. Locate the shade cloth and plastic sheets, along with the stakes and supports, that you’ve stored deep in the back of your garden shed. Remember that well-watered plants are more resistant to frost damage, and protecting the top is more important than protecting the sides of sensitive plants. Continue practicing good garden hygiene. Rake up those leaves and clean out the clutter in your garden. Don’t give pests a cozy winter home.
There’s always something to do when it comes to gardening even if it’s winter.
It’s Cleanup Time in the Vegetable Garden
UC Master Gardeners of Napa County
By David Layland
As our rainy season begins and temperatures start to fall, most gardeners are heading inside to stay warm and dry and read the latest seed catalogs and garden magazines, looking forward to the next growing season.
But if good garden sanitation isn’t done before the next planting season, what they may have been left in their gardens could come back to haunt them. Plant diseases can threaten their crops next year, as well as their neighbors’. Gardeners can take proactive steps to keep their gardens free of disease by cleaning up plant materials and disposing of them properly.
If you’ve harvested the last of your vegetables, it’s time to get the garden ready for winter. It might be tempting to just walk away and deal with the garden next spring, but a little work now will result in a healthier, more productive garden next year.
Cucumber vines, squash vines, and the dried remains of tomato and bean plants can harbor diseases. If you allow this disease-carrying residue to remain in the soil, there is a good chance the organisms will live through the winter and infect your new plants in the spring.
The first step is remove debris. Gather any plant material that appears to be infected and discard it not in your compost pile but in your yard waste can. Compost piles act as insulators during cold weather and throwing diseased material into it will cause contamination. Then dig under the remaining plant debris or place it in your compost pile. As the crop residue breaks down it will help improve the soil. If there are, heaven forbid, any weeds in your garden remove them as they can harbor plant diseases also.
The next step is to evaluate the condition of your soil. If your garden did not produce well this past season you may want to consider having your soil tested to see if any remediation is needed. You also want to protect your soil. Winter rains are wonderful but can lead to erosion so adding a layer of compost or mulch will protect and enhance your soil.
The final step in fall garden clean-up is to evaluate the garden and make notes to help you plan for next year’s garden. Include information on the crops and varieties grown this year to help decide about seed and transplant purchases next season. Make a note of the crops and varieties that did well and those that performed poorly. If there was a problem with a particular plant disease, note that too, so you can look for disease-resistant varieties. Even if this year’s garden was the best ever and you don’t want to change a thing, it’s still a good idea to jot down what worked well and what was a disappointment. Most importantly, note what was planted where so that you practice proper crop rotation. This is very important in disease prevention. If at all possible don’t plant members of the same plant family in the same place in succeeding years. For example, tomatoes, peppers, eggplant and potatoes are all in the solanaceae family. Rotate planting these vegetables with members or the cucurbitaceae family which includes cucumbers, squash and melons.
Vegetable gardening is such a rewarding hobby that it’s hard to face the end of the season. But it’s time to draw this activity to a proper conclusion by paying attention to these all-important fall chores. Once done, you can look forward to a healthy, well-prepared garden plot, ready for spring planting.
I’ve been enjoying fresh tomatoes for over a month and am starting to think about preserving some of these wonderful veggies (or fruits if you want to be technically correct) for consumption during the months when fresh tomatoes are not available.
Tomato fans such as myself are lucky as this is one veggie that is adaptive to several preservation methods. Tomatoes can be canned, frozen or dried with wonderful results.
Canning is the most popular way to preserve tomatoes and the one I prefer. The most common canning practice for preserving tomatoes is the boiling-water method which has been in use since the 1840’s. The equipment required is minimal and has not changed very much over the years. You’ll need to purchase canning jars, a waterbath canner with rack, a jar lifter and a wide-mouth funnel. All are reusable from year-to-year with only the canning jar lids requiring replacement. This year I’m trying something different and that’s a steam canner. An atmospheric steam canner is a two-part pot with an inner rack for holding jars and a tall cover that allows a steady stream of steam to flow around the jars. It requires only about 2 quarts of water to process seven 1-quart jars of high-acid foods, whereas a water bath canner requires about 2-1/2 gallons of boiling water to do the same job. A steam canner saves significant time and energy, doesn’t emit as much heat, and requires less heavy lifting compared with using a water bath canner. Steam canners have been in use since the early 1900’s but were not approved for home canning until June 2015. One thing to keep in mind is that canning is a science so to ensure the highest in quality and safety follow the reliable methods found in a guide such as the “Ball Blue Book Guide to Preserving.”
Freezing is the easiest way to preserve tomatoes and like canning prevents spoilage and bacterial growth. The only equipment needed is a sharp knife and a supply of freezer bags. Raw tomatoes can go into the freezer whole, halved or quartered and since freezing will split the skins you don’t need to peel. Thawed tomatoes won’t have great structure but what they will have is the flavor and nutrition of raw tomatoes.
Drying is best accomplished if you use a meaty paste variety. Tomatoes that were grown for slicing purposes do not work as well due to their high water content. Wash, core, score the ends, and dip in boiling water for 30 to 60 seconds to loosen the skin. Remove the skin, slice in half, and place in a dehydrator for 10-12 hours at 135 to 140 degrees. If you don’t have a dehydrator you can place the skinned and sliced tomatoes on a foil lined cookie sheet and bake at 170 degrees for 6-8 hours.
No matter which method you choose you’ll be glad that you preserved some of the summer harvest when you’re making dishes in the winter months that call for tomatoes and you have your very own flavorful canned, frozen or dried tomatoes.
Basic Tomato Sauce
Tomato sauce is the beginning point for many canning recipes. It is the basis for catsup, BBQ sauce, chili sauce, marinara sauce or it can be canned as is for use in fall and winter soups and stews.
20 to 25 lbs. ripe red paste tomatoes
¼ cup olive oil
2 medium yellow onions, finely chopped
2 large carrots, finely chopped (wash but don’t peel)
2 large celery stalks, finely chopped (include leafy part of stalk also)
2 to 4 large garlic cloves, finely chopped
Kosher salt and freshly ground black pepper
Bottled lemon juice or citric acid
Directions: Yields 6 to 7 pints depending on consistency.
- Quarter tomatoes. Place in a microwaveable bowl until full.
- Place bowl in microwave and cook on high for 15 minutes. Remove from microwave. Stir. Return to microwave and cook on high for another 15 minutes.
- Repeat above until all tomatoes are processed.
- Remove seeds and skins using a tomato strainer or food mill (you should have approximately 4 quarts of processed tomatoes). Set aside.
- Heat olive oil in a 6 quart stock pot.
- Add onion, carrots and celery to stock pot and cook until soft.
- Add garlic and cook for 1 minute. Add tomatoes.
- Simmer 2 to 3+ hours or until sauce reaches desired consistency. Stir frequently to avoid burning.
- If desired use an immersion blender for a smoother sauce.
- Add salt and pepper. Taste and adjust seasonings if necessary.
- If canning, add 1 tbsp. bottled lemon juice or ¼ tsp. citric acid to each sterilized pint jar and pour sauce to within 1/2″ of top. Cap and secure with band. Follow standard canning procedures and process in boiling water bath for 15 minutes.
Brown Marmorated Stink Bug
Last October, Dominique Shield from UC Berkeley contacted the Napa Master Gardeners about her need for a few volunteers to be a part of a Brown Marmorated Stink Bug (Halyomorpha halys) or BMSB survey. Her lab would be surveying Napa County for the invasive pest and needed gardens that have a diversified landscape containing vegetable and fruit crops, as well as some fruiting and ornamental trees.
I volunteered my property to be part of the survey and Dominique dutifully showed up every week to visually inspect the garden and a pheromone trap she had placed in one of my trees. The initial survey lasted about six weeks, and then commenced again in May. So far so good I thought.
In early June I was sitting at my desk when I noticed Greg Clark, Napa’s Ag Commissioner, poking around in the trees where this year’s pheromone trap had been placed. I thought it was unusual for Greg to be making house calls so I wandered outside to see why I was being honored with a personal visit. The reason for his visit was not good. Evidence of Napa County’s first BMSB had been found in the pheromone trap in front of my house.
Being the home of the first BMSB in Napa County is a dubious distinction to say the least. I had heard of the little critter, but did not know a great deal about it or what to do now that it had been discovered in close proximity to my vegetable garden, fruit trees, and vineyard. So far I have learned the following:
- It’s not a “little critter.” At maturity, it’s 5/8th of an inch long.
- Damage is caused by adults and nymphs sucking juices from fruit and seeds. Pictures of damaged fruits and vegetables are very unpleasant.
- Management options are limited. Chemical and biological controls require further testing. Hand picking may be the best control. (I’m sure my wife won’t mind patrolling the garden and fruit trees and hand picking BMSBs).
- On the positive side they are not harmful to people, pets or structures. They do not bite, sting, suck blood or spread disease.
The Ag Commissioner’s Office has hung additional traps around my property so visits to check activity are now part of my daily routine. I also have laminated pictures of BMSBs that I carry with me for easy identification. When patrolling my vegetable garden, fruit trees and vineyard, I picture myself as Bill Murray in Caddyshack and his assault on gophers.
The BMSB is a serious threat to agriculture and home gardens in Napa County. If you’re interested in more information, this link will take you to the UC’s Pest Alert for the BMSB: http://ipm.ucanr.edu/pestalert/pabrownmarmorated.html
In the future, I can guarantee you that I will volunteer to be part of any program that comes along involving the detection or eradication of the next pest du jour.
June is a very active month so here are a few suggestions to get you outside and working in the garden.
Reap the rewards of those well-established dry climate plants you have included in your garden over the last few years. Your ceanothus, many salvias and other native dry-plants are in the “do not summer water” category.
Plants that require water should be watered in the morning so they don’t become susceptible to fungus and insect infestation.
Prune spring-flowering shrubs that have finished blooming but have not been trimmed. Clip back flowering annuals after they have also finished blooming. Deadhead and deep water your roses, adding a layer of mulch.
Get ready for the heat of summer. Monitor moisture levels in the soil, and pay attention to how your garden looks at different times of the day to help recognize the difference between normal afternoon droopiness and real heat stress. Water deeply and infrequently to discourage roots from staying close to the surface where they are more subject to drying. With shrubs, trees and deep-rooted vegetables (tomatoes, melons and squashes) water weekly so that the soil is wet to a depth of at least three feet.
Mulch, mulch, mulch…but remember to try to leave some bare ground to encourage ground nesting native bees. A small, sunny patch is all they need.
Find spots in your garden to plant clumps of flowers that entice bees and other pollinators to visit. A list of native and exotic plants that attract and feed bees can be found at: http://www.helpabee.org/.
Continue to battle snails and slugs. Check trees and shrubs for aphid and scale infestations. Look for slow-moving bugs in the cool of the morning; hand-pick those, then dust below the plants with Diatomaceous earth (a white powder made from the fossilized remains of diatoms, one-celled algae that have a skeleton made of silicon). Be sure to use a dust mask so you don’t inhale the dust. The Integrated Pest Management site hosted by UC Davis has information to aid the home gardener deal with these pests: http://www.ipm.ucdavis.edu/index.html.
Plant beans, corn, cucumbers, peas, melons, kohlrabi, lettuce, radishes and endive. Sow seeds directly in the warm soil.
Plant more heat-tolerant veggies: Replace spinach with Swiss chard and potatoes with taro.
Put your seedlings of tomatoes, squash, peppers and eggplant into the warm ground. Plant also flower seedlings, such as gaillardia, coreopsis, lobelia, penstemon, statice, salvia, marigold, scabiosa, sunflower, zinnia and verbena.
Start more zinnias, marigolds, and sunflowers to replenish tired flowers in late summer.
Keep the weeds pulled, before they have a chance to flower and go to seed again. Otherwise, you will be fighting newly germinated weed seed for the next several years.
Remember, gardening is an ongoing process, and, while timing is important, don’t be overwhelmed by a sense of being too late to plant by some arbitrary date.
Now is the time to…
Celebrate a nearly “normal” rainy season
Fertilize annuals, perennials, shrubs and fruit trees. Please remember to follow directions and that “more is not better” when it comes to feeding with fertilizer. Take advantage of wet conditions, and don’t leave fertilizer on dry soil.
Aerate lawns that get heavy foot traffic to ensure that water, fertilizer, and oxygen reach the roots. Use a manual aerator to punch holes in small lawns. Or rent a power core aerator from a landscape equipment supplier, or hire a professional.
Check soil moisture on a regular basis. As we move out of the rainy season and temperatures start to climb, soil can dry out in a hurry. Dig down 3 – 6 inches in various spots in your garden, and if the soil doesn’t easily ball or wet your hand, it’s time to irrigate.
Remember native oaks have probably received enough water this season and shouldn’t be watered.
Apply surface mulches to your garden once the soil has warmed. This will help to retain moisture and protect soil and surface roots from the hot sun. Don’t mulch within six inches of tree trunks, and remember to leave some bare soil in your garden for native bee nesting.
Prune spring-blooming shrubs and vines that have finished flowering and deadhead flowering shrubs.
Divide perennials that don’t have a taproot and share with family, friends and neighbors. Lambs ear, daylilies, and iris are a few plants that can be divided while it’s still cool.
Sow seeds of cucumber, eggplant, melon, and squash directly in the soil.
Thin fruits on peach, pear, apple and nectarine trees, leaving six inches between fruits. Failure to do so may result in smaller fruit and branches that may break because of the weight of the fruit.
Continue weeding mercilessly. Weeds steal precious water and nutrients from your garden. Don’t let weeds go to seed; root them out when they are small and easy to deal with.
Not suffer a snail to live. One slime trail is one too many. Pick, trap and bait until snails and slugs are annihilated. But remember to use methods that are safe around dogs, children and other wildlife. Please refer to the IPM Pest Note on snails and slugs: http://www.ipm.ucdavis.edu/QT/snailsslugscard.html
Q It is generally known that a female honeybee’s stinger rips away after stinging. Why would natural selection favor such a defense mechanism?
A This defense works for the colony, if not the individual. Those females, worker bees, cannot reproduce, but their self-sacrifice defends the egg-laying queen. Also, the parting of the bee and stinger exposes a gland that releases a pheromone alerting other colony members to sting the victim at that spot. David Roubik, entomologist, Smithsonian Tropical Research Institute, Smithsonian, November 2015
Now is the time to…
Check your soil temperature
It started in late February and March at the big box and large chain stores in our area. Veggie starts were here and ready to be planted. But is this the right time to plant or is this a false harbinger of spring?
The answer to this question is don’t plant your starts just yet. It’s way too early. Even if February, March and early April weather is sunny and in the 70’s it’s still too early for many of the heat loving vegetables to be thrust into the ground. The temperature of the soil is what matters and in our area soil is still in the high 40’s to low 50’s which is too cold for tomato, pepper, squash, eggplant, beans, cucumbers and pumpkin plants to put on any active growth. The less active the growth cycle, the less ability the plant has to stave off insect and disease problems.
Most independently owned nurseries and garden centers don’t start bringing in summer vegetables until spring is officially here. This is also why the Napa Master Gardeners hold their annual tomato plant sale on April 23rd. Any earlier and you would find it necessary to keep your plants in an area where it’s warm and bright but not in the ground. If you want to give your plants the best chance at survival in your garden you’ll wait until the soil temperature is at least 60 degrees. If you have ever found your tomato plant suffering from the dreaded blossom end rot it could be due to planting before the soil was warm enough.
If you want to plant something before soil temperatures hit 60 degrees consider leafy vegetables, root vegetables or corn. Cabbage, Swiss chard, lettuce, and spinach can be planted when soil temperature is at least 40 degrees. Beets, carrots, onions, parsnips, radishes and turnips also require just 40 degree soil temperature. When the soil temperature hits 50 degrees you can plant corn.
A soil temperature probe can cost as little as $8 to $10 and it’s well worth the expenditure if you want to plant your vegetables as soon as possible and also plant them at the right soil temperature.
For more information check the UC Master Gardeners of Napa County planting schedule on our website. http://ucanr.edu/sites/ucmgnapa/ files/141547.pdf
Now is the time to…
First the cold and wind awoke us. Then the rain came down to soak us, And now before the eye can focus – Crocus. Adapted from a verse by Lilja Rogers
The recent weather has been dry, but it’s exciting to get out into the garden and discover plants popping up that we’ve forgotten we’ve planted. Our orders to the seed houses have arrived. It’s nearly time to set up tomato supports that have been in the shed. The weeds pull easily from the wet soil. It’s spring!
Be patient. The last killing frost of the year is usually about mid-March, but can be as late as early May. Have a plan to protect your sensitive plants.
Check your irrigation system. Add emitters for trees and shrubs that have grown. Take off the ends of your drip system lines to flush the lines. Add filter screens to help reduce clogging and keep the rate of water applications consistent.
Begin fertilizing. For lawns, 16-6-8 or a maximum of one pound of actual nitrogen to each 1,000 sq. ft. In late March, when established shrubs and citrus trees have begun active growth, apply a complete formulation of 10-10-10. For perennials and herbs, feed lightly when they begin active growth. Remember, these recommendations are for ideal conditions. Many plants seem to think it’s much later in the season, but don’t jump the gun with fertilizer just to see a frost come along and turn beautiful new growth into the likes of canned spinach.
Control pests. Watch for slugs and snails on susceptible plants, organic litter, pots – let’s face it, just about anything can harbor these mollusks. Trap them or bait them with an iron phosphate product. Chickens love slugs and snails and will be very willing to help dispose of the little critters.
Start vegetable seeds indoors. Tomatoes, peppers, eggplant and cucumbers need about 8 weeks before being ready to transplant. If you want to start your vegetable garden by mid- May then now is the time to get those seeds germinating.
Start flower seeds indoors or wait to direct-seed outdoors next month. Good choices are marigolds, nicotiana, zinnia, portulaca, globe amaranth, cosmos, celosia, verbena rigida, salpiglossis and wallflowers.
Plant bulbs and tubers: Calla lilies, dahlias, tuberoses (polianthes) and tigridia.
What else: This is also a good time to attack any weeds that have appeared, clean winter debris from the garden beds, clean-up your tools and get ready for the start of spring. Outdoor planting time is almost here!
For more information check the UC Master Gardeners of Napa County planting schedule on our website. http://ucanr.edu/sites/ucmgnapa/
From Valentines to Weeds
Whether February days are stormy and wet or cold and dry, there is plenty to consider doing in the garden.
If it’s a rainy day, take the opportunity to do some garden “bookkeeping.” Set up a garden calendar or journal. Have a page for seed-starting dates, fertilizer dates, watering schedules, first harvest, and a space for notes on what did and did not work. Consider a page for daily temperatures and rainfall. If you’re a “techie” there are apps available so that you can do all of this on your smart phone or tablet while in the garden.
It might seem early to be thinking about planting, but fruit trees, shrubs, vegetables and flowers can all go in the ground this month if the soil is not too wet. This is also a good time to dig up and divide overcrowded clumps of perennials.
Valentine’s Day is imminent. Potted red camellias, cerise azaleas or white gardenias make colorful gifts that can transition to long lives in the garden. Even if you’re not buying for a Valentine, February is a great month to visit nurseries to view color options on blooming camellias and other winter-flowering shrubs and plants.
Bare-root asparagus and rhubarb are available, but not for long. Both are long-lived crops that will produce for years in an area they like.
Potatoes are also in nurseries now and can be planted along with carrots, peas, onions, radishes, lettuce, spinach, parsley and chard. To these familiar vegetables, consider adding Asian greens, cresses, arugula and kales.
If you grow warm-season vegetables from seed, it is time to pull out your warming mat and set up your lights or find your sunniest window. Early in the month, start seeds for cabbage, cauliflower, onions, parsley and lettuce. Later in the month, start seeds for your favorite tomatoes, peppers, eggplants and basil.
If you have raised beds in your garden or hills with ample compost, winter squash and pumpkin seeds can go directly in the ground now. They will ripen and be ready to harvest sooner.
If you see evidence of snails or slugs (slimy trails are one clue), try setting out inverted flower pots, propped up a tad on one side so the pests have a way in to the “snail hotel.” Collect your victims in the morning and throw them away or feed to your chickens. This non-toxic approach keeps chemicals out of your garden and away from pets and children plus you’ll have happy chickens.
Spray peach and nectarine trees to prevent peach-leaf curl just when the buds begin to bulge and show color. Alternatively, you can pick off the crinkled leaves as they appear, put them in a bag and dispose of them. Eventually the tree will replace them with healthy leaves.
Weeds begin to appear now. Tackle them with hula hoes or your favorite implement. Try to catch weeds early, before they go to seed. If they have set seed, toss them in the yard-waste bin. Weed seeds often survive home composting. If they haven’t set seed the weeds can be composted.
Plan, Plant, Maintain–and Enjoy
The cooler winter months provide an opportunity to take stock of the garden and plan for the coming year. You can read about gardening, peruse garden catalogs, create a list of things to accomplish, draw plans and clean tools. Expand your gardening knowledge. Read books and articles. Sign up for classes and workshops. Take advantage of the winter rains to plant. A winter garden can be colorful, productive and satisfying in its own way.
Make sure you are ready for spring. Sharpen your tools, scrub your pots, and refresh your supplies of fertilizer and soil amendments. If you are unhappy with some areas of your garden, sketch a new plan.
If you don’t already keep a garden journal, it’s a good time to start. Use your journal to track the varieties you plant, planting dates, weather, harvest dates, fertilizing regimens, pest or disease problems, yields and any unusual growing conditions. A journal is especially helpful if your garden contains a wide variety of plants and if you experiment from year to year.
Check your tools for rust and dirt. Replace handles or replace the entire tool if needed. Sand and oil salvageable handles to prevent splinters. Clear, clean and organize your garden shed to get ready for a new busy season.
Begin pruning fruit trees, roses and shrubs. The best time to prune most fruit trees is when they have lost their leaves and are dormant. It is much easier to see what you are doing then, and by pruning in winter, you will stimulate growth. Young fruit trees need pruning to encourage growth and proper branching, which will make them easy to care for, structurally sound and productive. Winter pruning of mature trees increases fruit size and quality and will open up the canopy to accommodate air flow, fruit thinning and harvesting.
Avoid working or walking on wet soil to minimize compaction. But if the ground is not too soggy, you can plant a variety of vegetables, shrubs and trees now. Remember that starting vegetables from seed gives you more choice than using starts from the nursery.
Plant these bare-root plants now: artichokes, asparagus, azaleas, blackberries, camellias, grapevines, onions, raspberries, rhubarb, strawberries, roses and fruit trees.
Sow these vegetable seeds now: arugula, Asian greens, bell beans, broccoli, cabbage, cauliflower, green onions, lettuce, peas, salsify and spinach. Check instructions on the package for recommended soil-planting temperatures. Some vegetable seeds may prefer a head start in warm soil indoors.
And, finally, take time to enjoy your garden. Often we get so caught up in the planting and maintenance that we overlook the beauty of each season and forget why we garden in the first place.
What to do in December…by David Layland
Preparing for El Nino
After four years of dwelling on drought it looks like we will have the opportunity to shift gears and address having too much water rather than too little.
Recent forecasts by the National Weather Service indicate that Northern California stands a better than 50% chance of getting significant precipitation from this winter’s El Niño weather pattern with the bulk of the precipitation falling in January, February and March. If you haven’t already done so, it’s time to start preparing for El Nino.
Vegetable and Flower Gardens. Now is a good time to remove last year’s annual vegetables and flowers and add them to your compost pile. If you’re not growing cool season flowers or vegetables you will want to protect your soil by spreading straw or planting a cover crop. Fava beans are a great cover crop and are a Master Gardener favorite as they protect the soil and then feed the soil as a green manure.
Yard Clean-up. Make a general inspection of your entire yard area for debris, outdoor furniture, or other objects that could be blown by strong winds. An afternoon spent tidying up the yard and either storing furniture and other loose items indoors or securing them can prevent a frantic scramble to collect items that have landed on your roof or in your neighbor’s yards.
Gutters and Downspouts. Make sure gutters are clear of leaves and other debris and connections between gutters and downspouts are functioning properly. Faulty gutters and downspouts can also lead to soil erosion adjacent to buildings and serious water and foundation displacement problems in basements and crawl spaces. Make sure downspouts direct water away from buildings and do not create standing water. Storm water runoff from impermeable surfaces (e.g., roofs, driveways, and patios) should be directed into a collection system to avoid soil saturation.
Roofs. Inspect your roof for loose tiles, holes, or other signs of trouble. Inspect flashing to ensure water is directed away from seams and joints.
Bare Ground. Make sure your yard does not have bare areas which could be sources for mudflows during a storm event. The fall is a good time to put down mulch and establish many native plants; it may be possible to vegetate these bare areas before the storm season.
Trees. Have any trees that appear to be weak or damaged inspected by an arborist. In high winds, downed trees and branches can knock out power or seriously damage homes and vehicles.
The Napa County Master Gardeners help desk is staffed every Monday, Wednesday and Friday from 9am to noon. If you have any questions you can call us at 707.253.4143, stop by our office at 1710 Soscol or send us an email at firstname.lastname@example.org.
What to do in November … by David Layland
Start with a postmortem to see what worked for you this past summer and what didn’t work. After things die back, you can evaluate your drip irrigation system and see where any leaks are and fix them. You can also take steps to adjust your emitters if plants received too little or too much water.
Harvest olives for making oil or preserving. The olive fruit fly is a serious pest throughout California. In order to minimize its damage make sure you clean-up fruit as soon as it falls to the ground to prevent the olive fruit fly from overwintering in the soil.
Make a note of where you planted your crops so you can rotate them next spring to minimize the possibility of soil-borne diseases.
Consider whether plants got enough or too much sun. Trees grow and can shade planting beds that need full sun.
Plant spring bulbs (daffodils, hyacinths, grape hyacinths, etc.) If the very warm fall weather keeps up, our fall planted bulbs and perennials will thank us for waiting a little while.
Plant cover crops (also called green manure or compost crops) such as fava beans. Plants in the legume family are capable of gathering unusable nitrogen from the air and converting it into usable nitrogen in root nodules, with the help of special bacteria. Legumes increase soil fertility as they decompose, thus releasing the stored nitrogen. In fact, any cover crop that is plowed under will release nitrogen as the crop decomposes. This is the origin of the term “green manure.”
Pull up old crops and rake up leaves and compost, compost, compost. You’ll need fresh compost in the spring so start now.
Want your garden to look as beautiful as the UC Master Gardeners Demonstration Garden at Connolly Ranch (pictured above)? It’s never too late to start and it’s actually a great time to prepare your garden for fall! Master gardener David Layland has all you need to know in his timely article.
Now is the time to…by David Layland
Prepare fall garden beds. Dig in compost and fertilizer and let it mellow a week before planting. Vegetables grown in most California soils often require some fertilizer for best growth. Nitrogen is the most important nutrient and can be applied using either organic forms, such as manures or compost, or inorganic forms (chemical fertilizers) to supply needed nutrients. Often a combination of the two forms gives better results than either used alone. See more at http://cagardenweb.ucanr.edu/Vegetables/. In general, late summer is not a good time to fertilize existing plants. Plants that are stressed due to the heat do not want fertilizer.
Deadhead flowers. Improves the look of the summer garden. Spent flowers look untidy. Leave these flowers on only if you are trying to get a plant to naturalize or if you are interested in attracting birds.
Continue weeding. It’s hot, and we might feel like sitting on the garden swing, but weeds could be the largest contributor to that not-so-nice look. Remove the competition from the plants you want to flourish.
Keep up with your vegetable garden. It will continue to produce long into the fall by following a few simple guidelines:
- Remove those over-ripened zucchini on the vines. You may never want to look at a zucchini again, but once a plants fruit have gone to seed, the plant thinks it’s done its job and begins to decline. Plants like squash, beans, peppers and eggplant will stop producing new vegetables if the existing vegetables are left on the plant. It will pay you to search out the hiding behemoth vegetables every few days and remove them from the vine.
- Make sure the vegetables are getting enough sunlight. Some-times by late summer foliage is so thick sunlight can’t penetrate. Plants ripen faster in sunlight and produce tastier fruits. Vegetables that are growing in deep shade are more susceptible to insects and diseases. Go ahead and gently thin some leaves to let sun in.
Monitor water. July is the month in when gardeners typically start to observe water problems. Check your watering system frequently to see if filters, emitters and sprinklers are clogged and if water is getting to the target. Be sure water is penetrating to the full rooting depth.
Trees, shrubs, and perennials that you planted recently need extra watering and their root balls should not dry. Water thoroughly and evenly to encourage deep root growth.
Weeds are bullies and take water and nutrients away from your plants. Get rid of them and don’t let them go to seed.
Plan for fall. While you are watching and waiting for your summer garden to mature, take some time and plan for fall. Fall gardens do best when started in late July or August so the plants are well established before cool weather comes. Begin by preparing beds as space becomes available and as weather permits.
Make a list of which plants are working and which are not. Note particularly successful plant combinations that deserve to be repeated elsewhere in the garden. That way when the fall planting season arrives, you’ll be prepared!
Solarization. This is also a good time to do Soil Solarization while the sun is at its hottest and the days are long you can kill off pests, weeds and disease in your soil using the power of the sun. For beds that you don’t have planted, remove weeds and smooth out the soil, water the soil then cover with clear plastic sheet securing the edges under soil. This will create a cover to steam the soil using the sun as it heats the water in the soil. If you do this for 4-6 weeks starting now you will have a clean bed ready for planting your winter vegetable by late August. For full details of this process see our website http:// ucanr.edu/ucmgnapa and look for the handout on Soil Solarization under Garden Resources /Healthy Garden Tips.
What to do in the garden in June
by UC Master Gardener Jane Callier
Be fire safe and sun safe. Clear brush, weeds and dry grass away from your house. If you live on a large property, monitor invasive plants like brooms and pampas grass, they can become fire hazards. While working outside, don’t forget to protect yourself from the sun by wearing a brimmed hat and high SPF sunscreen and staying well hydrated.
Water wisely. Proper watering is the most important summertime garden task. One of the best ways to achieve efficient, non-wasteful watering is by using a drip system with a timer. Water deep-rooted vegetables and fruits such as tomatoes, melons and squash to a depth of 3 feet; water most shrubs and trees to 3 feet as well. Deep, infrequent watering is the key. Many shrubs and tree plants can be watered only once a month when it is cool, or once every two weeks in hot weather. Watering by hand usually doesn’t do an adequate job. Plants suffer from shallow watering because roots stay too close to the surface and they are subject to drying out.
Take an objective look at the comfort level of your garden. Does the sun beat down relentlessly in all areas of your garden? Consider strategically planting a shade tree. If, on the other hand, if tree vegetation has grown to where it blocks the sun, maybe it’s time to trim some trees.
Plant some herbs. They’re easy to grow and most love the sun. It’s not too late to plant annuals.
Don’t get lazy. Keep feeding citrus and blooming plants at the recommended rate. Deadhead flowering plants, but leave some pods for the birds. Pick up fallen fruit to discourage rats, ants and wasps and some diseases. As always, don’t let the weeds go to seed.
Connolly Ranch is pleased to welcome a new monthly article from the UC Master Gardeners! Please join us in thanking our partners for answering your questions and offering great gardening advice each month. If you have a question or a topic you would like covered, please email Yvonne Rasmussen at email@example.com.
Plants in Drought
by Yvonne Rasmussen, UC Master Gardeners of Napa County
What happens to our plants as they undergo water stress? To answer that, we have to know a little about how plants use water.
Plants use water in three main ways: to maintain their turgidity, to transport water-soluble nutrients and to photosynthesize. A turgid plant is erect, not limp. When plant cells have enough water, they maintain their shape. When cells lack water, they shrink and the plant wilts, or loses turgidity. By the time a plant wilts, many plant processes have stopped and the plant will take some time to recover.
For photosynthesis, plants have small pores in their leaves called stomata. These pores open to exchange gases: carbon dioxide in and oxygen out. As the oxygen goes out so does water vapor. This evaporation cools the leaves but also draws in replacement water from the roots—like sucking water through a straw.
When the water enters the roots, it carries soluble nutrients along with it—compounds that are in solution in the soil, such as fertilizers.
Water also assists photosynthesis, the process of making food for the plant. Water combines with carbon dioxide to form sugars and gives off oxygen and a little water, too. If you have ever lain under a tree on a warm day, you may have felt moisture dripping from the canopy. That’s some of the excess water, and this process partly explains why shade trees have such a welcome cooling effect.
When a plant does not have enough water to fill all these needs, it has to adapt.
A water-stressed plant goes through a series of steps to conserve its resources. One of the first things it does is to change the chemical content of its cells. This action thickens the content of the cell—like putting antifreeze in a car—so the cell is less likely to lose water and the plant retains more turgidity.
This more concentrated cell solution also helps the roots increase their water uptake, if the soil has any water. Water-stressed plants will also close their stomata: no gas exchange and thus no water loss.
For most plants, closing the stomata also shuts down photosynthesis. With no new food being made, plants use up their reserves. Many plants will move food resources from non-essential functions like growth and fruit production to essential processes that keep them alive. Root activity stops and cells stop growing and multiplying. Plants initiate senescence—the onset of old age—and foliage, branches and roots begin to die. Next, plants prepare themselves to drop these dead parts. First, they drop any fruit, then leaves and eventually branches. At some point, the whole plant may die.
The effect these responses have on the plant depends on its stage of growth when the stress occurs. In the early spring, plants are growing roots and pushing out new buds; mild stress can stunt this growth. Under-developed root systems can cause problems later, if plants do not have sufficient roots to take up water and nutrients in summer. Poor bud development in spring can restrict growth during the rest of the year and sometimes into the following year as well.
If the water stress occurs while the plant is flowering, flower buds may drop, open poorly or not develop into fruit. Once the flowers have been pollinated and the fruit begins to develop, water stress can stop cell division and expansion. The result is very small fruit or fruit that will not ripen. Peaches and other stone fruits that are stressed during seed development may form split pits that can cause fruit to split open and spoil.
You can reduce water use and still keep plants alive, but they may not be as lush or productive as in past years. The key to helping plants survive with less water is good observation skills. Many plants will manage if you slowly reduce the amount or frequency of water you provide.
Know your soil type and build healthy soil. Healthy soil holds more water. Mulching keeps roots cool and reduces soil evaporation. Be sure to keep mulch a few inches away from the base of plants and trees.
Change your watering regimen to adjust for day length, temperature and wind. Day length is important because plants will actively photosynthesize as long as the sun is out. Plants need more water during hot, windy, sunny days in the middle of summer when days are long.
Knowing how drought-tolerant your plants are is also important. Plants that have evolved where summers are dry will usually tolerate more stress or may have means of adapting to a dry season. If you must let some plants die, consider replacement costs and value to your landscape. Keep your trees and big shrubs alive and let the little guys go.
Look for drought tips and more information as well as workshops on the drought in June and August on our website at http://ucanr.org/ucmgnapa
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. Napa County Master Gardeners (http://ucanr.org/ucmgnapa/) are available to answer gardening questions online, in person or by phone, Monday, Wednesday and Friday, 9 am to noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143.
UC Master Gardeners of Napa County welcome the public to visit their demonstration garden in Connolly Ranch’s Garden area on Walk-in Wednesdays the first Wednesday of each month starting May 6 from 3 to 5 pm.
Originally written for UC Master Garden column in the Napa Valley Register on May 16, 2014.