By Susanne von Rosenberg, UC Master Gardener of Napa County
It's been impossible not to notice how different our fall season is from what we were used to in the past. Rains come four to six weeks later, if they come at all. We get heat spells into October and sometimes November, and big fires are burning somewhere.
Napa County Master Gardeners have been providing workshops and other information on fall vegetable gardens for more than 10 years. Fall vegetable gardening used to feel almost like a freebie: just water the plants long enough to get them well established, and by early to mid-October nature would begin to water them for you. Even if you had to water periodically, the plants needed less water because of the predictably cooler and more humid weather.
Recently, I've had questions about whether fall vegetable gardening still makes sense, and how to deal with the changes. Yes, it still pays to put in a fall vegetable garden, but we need to consider the changes in rainfall patterns and autumn temperatures.
The best things you can do to make your garden more resilient are to improve the health of your soil and to mulch your garden. Healthier soil holds more water, and it also provides better conditions for plant growth. A plant in healthy soil will be able to handle more stress than a plant in more marginal soil. Mulching helps conserve water, reduces weeds (which compete for the available water) and adds organic matter to the soil if you use a mulch composed of organic material.
Given the changes in rainfall patterns, be prepared to water your fall vegetable garden. Plants will need less water than in late spring or summer because autumn temperatures are lower and days are shorter. But don't do what I've done (more than once) and keep waiting for the rain that never comes. I've lost or stunted several crops because I kept expecting it to rain “any day now.”
These days I water using the same basic principle as I do in the summer. When the soil in a vegetable bed is dry 1 to 2 inches down, it's time to water, even if it is December. Seeds and young seedlings need more frequent watering.
The more challenging question these days is “When should I plant?” We used to say that, in most areas in Napa County, you could plant seedlings for fall crops such as broccoli and cauliflower by mid-August for a harvest around the end of October. Planting as late as mid-September would give you a crop by late November. Planting after the middle of September would most likely mean that your “fall” crop would mature in the spring.
I no longer plant in mid-August. The risk that my plantings will fail due to heat is just too high. Even if I can keep the seedlings alive with shade and a lot of water, they will be stressed and therefore less productive and more susceptible to disease and insect pests.
I now plant no sooner than the beginning of September, and more typically toward the middle of September. Planting later in the fall means that my first harvest is delayed. I can partially make up for this by planting some vegetables that mature more quickly than broccoli and cauliflower, such as Asian greens and lettuces.
I also grow some vegetables in containers that I used to start in the ground. I can grow them in the coolest areas of my garden, even bringing them inside during the hottest part of the day. Peas work well when grown this way.
Also, for fall planting, it's a good idea to choose the varieties with the shortest days to maturity. Broccoli harvest can vary from 55 days to more than 90 days from transplanting. Choosing bolt-resistant vegetable varieties is another important tactic for fall planting.
Although planting later in the season delays the harvest, warmer temperatures mean that plants grow later than they have in the past. Plants need light to photosynthesize, and the shorter days and lower light intensity in the fall reduce the rate of photosynthesis. However, photosynthesis also requires a certain minimum temperature; depending on the plants, photosynthesis virtually stops at temperatures below 38°F to 50°F. For most plants, the rate of photosynthesis is highest between 50°F and 68°F. (Also worth knowing: Photosynthesis nearly stops at temperatures above 104°F.) The higher fall temperatures that we have been experiencing won't compensate for the reduced sun intensity, but they do help us get a slightly longer fall growing season.
Food Growing Forum: Napa CountyMaster Gardeners will present a discussion of “Perennial Vegetables, Garlic and Alliums” on Sunday, October 10, from 3 p.m. to 4 p.m., via Zoom. Register here to receive the Zoom link.
Free Guided Tree Walk: Join Master Gardeners of Napa County for a tree walk in Fuller Park in Napa on Tuesday, October 12, from 10 a.m. to noon. Limited to 12 people per walk. COVID safety protocols will be followed. You will be asked health questions and asked to sign in. Face masks and social distancing are required. Register here.
Got Garden Questions? Contact our Help Desk. The team is working remotely so please submit your questions through our diagnosis form, sending any photos to firstname.lastname@example.org or leave a detailed message at 707- 253-4143. A Master Gardener will get back to you by phone or email.
For more information visit http://napamg.ucanr.edu or find us on Facebook or Instagram, UC Master Gardeners of Napa County.
By Donna Woodward, U. C. Master Gardener of Napa County
Twice a year, Napa County Master Gardeners conduct vegetable field trials. Members of the field-trial committee plant three different varieties of the same vegetable and monitor the results so we can share what we have learned with the public.
In the spring of 2018, we chose sweet peppers for our trials. The three varieties chosen were Gypsy (a hybrid), Golden Giant (a hybrid) and Jimmy Nardello (open-pollinated).Seeds for both hybrid varieties were purchased from Burpee; the Jimmy Nardello seeds came from Baker Creek.
We started the seeds in 4-inch pots in a greenhouse and planted the seedlings in our gardens between April 25 and May 5. Drip irrigation was recommended. Since peppers like rich soil, we were advised to amend the soil with compost and add a balanced fertilizer, such as 5-5-5. We planted the peppers 18 to 24 inches apart and were cautioned to keep them well-watered in hot and dry weather but to avoid getting water on the fruit.
All three varieties produced plenty of tasty sweet peppers. Jimmy Nardello was a pretty, bright red pepper with a sweet, slightly spicy flavor. Gypsy was a yellow-green pepper which also had a piquant flavor. Golden Giant, true to its name, produced very large, rounded fruit with thick flesh. The others were elongated, tapering from broad shoulders to a pointed tip.
Our committee generally reported good results for all three varieties. All benefited from some support, but it was especially important for the Golden Giant. Small tomato cages worked well. The peppers did not suffer much insect damage, the only report being in mid-September. All three varieties were somewhat vulnerable to sunburn and blossom-end rot.
Participants completed a survey rating the three varieties, on a scale of 1 to 5, for flavor and productivity. The scores were all high, ranging from 4.3 to 4.6, with Gypsy taking the honors.
However, in accumulating the participants' comments, a more complicated picture emerged. Individual experiences were often contradictory. The only variety that got predominantly positive reviews was the Jimmy Nardello. It received the most praise for flavor and was also the most prolific. It was the earliest to mature, about a month earlier than the other two, and continued to produce long into the season.
Reactions to the other two peppers varied widely. Comments regarding Golden Giant's flavor included “bland,” “delicious,” “good but not outstanding” and “bitter.” Comments on Gypsy were also at odds: “prolific and tasty;” “not prolific enough and not tasty or sweet;” and “best taste; pretty colors.”
How do we explain the difference between the numerical scores and the comments? Apparently rating by numbers doesn't tell the story. The comments bring out some of the variables that can influence outcomes in such trials.
Growing conditions can vary widely within Napa Valley. Soils, sun exposure and elevation can differ even within a small area. The pepper variety that performs best for you may well depend on the conditions in your garden. There was also some variability in how participants followed recommended cultivation guidelines. A few tweaks in growing practices might yield different results. We gardeners all know that trial and error is a great teacher.
Perhaps naming a winner isn't the most important outcome of this trial. All three of these pepper varieties can produce excellent fruit, as can many other sweet pepper varieties. The most valuable lessons relate to growing peppers in general:
Peppers are susceptible to sunburn. Planting them close enough for the leaves of plants to just touch will help protect them from sunburn.
Leaf puckering is a symptom of phosphorus deficiency. Phosphorus affects the health and growth of the plant and helps the fruit to set and develop. Dig some into the planting hole when transplanting. Most pepper plants appreciate a few tablespoons worked and watered into the soil every couple of weeks during the growing season. If leaf puckering occurs, use more.
Garden-grown sweet peppers are delicious. They are a wonderful addition to green salads, stir fries and other dishes, adding color, flavor and nutrition. If possible, make room for sweet peppers in your vegetable garden this spring.
Workshop: “Sustainable Vegetable Growing” (Four-Part Series) on Sundays February 23, March 1, March 8 and March 15, from 2 p.m. to 4 p.m., at the University of California Cooperative Extension, 1710 Soscol Avenue, Napa. For more details & online registration go to Online registration (credit card only) or call 707-253-4221.
Workshop: “Spring and Summer Vegetables” on Sunday, March 8, from 1 p.m. to 3 p.m., at the Yountville Community Center, 6516 Washington Street, Yountville. Do you want nutritious, easy-to-grow and utterly fresh food from your garden this spring and summer? To register, call the Parks & Recreation Department at 707-944-8712 or visit the department's web site.
The UC Master Gardeners of Napa County are volunteers who provide UC research-based information on home gardening and answer your questions. To find out more about upcoming programs or to ask a garden question, visit the Master Gardener website (http://napamg.ucanr.edu) or call (707) 253-4221 between 9 a.m. and noon on Mondays, Wednesdays or Fridays.
- Author: Monica Finigan, UC Master Gardener Napa County
Tomatoes are a mainstay in most summer gardens. Delicious in warm-weather salads, they are also essential to many cooked dishes. And the plants require far less water to grow than many other vegetables. Here are some tips to help ensure a successful harvest.
Wait to plant until all danger of frost is past and the soil is sufficiently warm. Cool weather makes tomato plants more susceptible to diseases and pests and slows plant growth.
Prior to planting, “harden off” tomato seedlings by placing them outside for about a week. Put them in a sheltered location, and then gradually expose them to garden conditions. If frost threatens, bring the plants indoors or cover them.
Choose stocky transplants six to eight inches tall with healthy green leaves. Check the bottom of the container. If roots are growing out the bottom, the seedlings may have been in the pot too long and may be root bound.
Water seedlings a few hours before planting and make sure the soil in the planting area is moist. Pinch off all but the top two sets of leaves. Carefully remove each seedling from its plastic pot without handling the fragile stem. Loosen the roots. Set the seedling in a planting hole deep enough to cover the exposed stem when the hole is backfilled. Those little hairs on the stem will form roots if buried and will help give your plant a good foundation.
If the seedlings are in biodegradable pots, you can plant them in the pot, but break up the pots slightly so the roots can easily grow into the soil.
Fill the planting hole with soil, press the soil firmly around the plant, and then water the area thoroughly.
Tomatoes need full sun and plenty of room to grow. If planting in a pot, choose a large one. If planting in the ground or in raised beds, space seedlings 24 to 30 inches apart. If you don't intend to stake or cage them, they will need even more room.
Most tomato plants benefit from some type of support. Cages or stakes keep them off the ground, maximize space and make harvesting easier. I like the rectangular wire cages that collapse for winter storage.
Place cages around seedlings soon after planting to avoid damaging the plants. Insert two strong stakes on both sides of the cage to provide support when the plant becomes heavy with fruit. Check the ultimate height of the variety you are planting to determine the height of the cage you need. The openings in the cage should be large enough to accommodate your hand at harvest time.
If you prefer to stake your plants, select stakes six feet long and one and one half to two inches wide. Drive them one foot into the soil four to six inches from the plant. As the plants grow, pull the stems toward the stakes and loosely tie them at intervals of ten to twelve inches. Use strips of cloth or other flexible material. Prune the plants to a few main stems to keep them from becoming too heavy.
Tomatoes need regular watering. Fluctuations in soil moisture can promote fruit cracking and blossom-end rot. Keep the area weeded. Weeds compete with your tomatoes for nutrients and water and can harbor pests. A three- to four-inch layer of mulch will minimize weeds and help retain soil moisture.
Don't fertilize until the plants are flowering and fruits are forming. Too much nitrogen fertilizer in the beginning will encourage green growth but will delay fruit formation. Once the plants start fruiting, give them a nitrogen fertilizer every four to six weeks. Follow the instructions on the label. Place the fertilizer alongside the growing plants in shallow grooves or on the soil surface. Water it in thoroughly.
Harvest tomatoes when they reach full color. Store at room temperature—not in the refrigerator—to enjoy their flavor at its best.
Tomato Plant Sale: U. C. Master Gardeners of Napa County will hold their fourth annual Tomato Sale and Education Day on Saturday, April 23, from 9 a.m. until sold out, in a new location at 1710 Soscol Avenue, Napa. Choose from 28 varieties, including heirlooms and new varieties in a range of colors. These healthy, Master Gardener-grown seedlings include types for fresh eating and for sauce.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/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. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
Just what is a weed? Some say that a weed is any plant growing where it is not wanted. But let's take a look at weeds from some different angles. Maybe they aren't always the nuisance we think they are.
Many so-called weeds are attractive, with verdant foliage (lambs quarters, English daisy), colorful flowers (chicory, scarlet pimpernel, day lily, and buttercup oxalis) or interesting growth patterns (plantain, willow herb and mallow). Others make lush groundcovers or turf (clover, common chickweed, Bermuda grass).
Some weeds provide children with great entertainment. Perhaps you remember blowing dandelion seed pods, making filigree “scissors,” sucking the sweet-sour stems of oxalis, stringing wild radish fruit necklaces or picking bouquets for doll parties and friends.
More importantly, and more usefully, weeds can communicate valuable information about the soil in which they grow. A happy weed can indicate what other types of plants would do well in that area, or what improvement a soil might need.
If you see yellow nutsedge, dock or foxtails, the site probably has soggy, swampy conditions on occasion. In that situation, ornamental willows, Japanese and Siberian iris, ligularia and dogwoods would do well, too.
Chicory, annual bluegrass, bindweed and chickweed indicate compacted soil. Planting a strong-rooted cover crop, such as white lupines or sweet clover, would help break up the soil and release nitrogen as well. Adding organic compost could also help aerate and lighten the soil.
Dandelions, sorrel, annual bluegrass and plantain prefer acidic soil, with pH below 7.0.Where those weeds do well, you can probably grow hydrangeas, blueberries, rhododendrons and azaleas, which also thrive in “sour” soil.
Alkaline soil, with a pH above 7.0,is hospitable to poppy, sagebrush and scarlet pimpernel, but also to choice ornamentals, such as lilac, lavender, dianthus and baby's breath.
Fertile soil supports chickweed and lambsquarters. The presence of redroot pigweed indicatesan abundance of nitrogen. Red clover suggests the soil is high in potassium, while wild mustard signals phosphorus. Heavy-feeding vegetables—corn, broccoli, lettuce, melons, squash, tomatoes and peppers—should grow well in such rich soil.
Your soil may have poor fertility if you see daisies, shepherd's purse or black medic. Not to worry. Many perennials, including coreopsis, salvia and stachys, flower better in lean soil. Legumes, beets, carrots, peas, radishes and sage tolerate low-fertility soils as well.
Besides indicating soil conditions, weeds can also improve the soil. Strong-rooted weeds like dock, dandelions and mallow push deeply into soil, opening air spaces and improving drainage. Shallow-rooted weeds like ground ivy, knotweed and purslane act as groundcover and help prevent erosion and soil crusting. Some weeds in the legume family, such as clover and black medic, add nitrogen that more desirable plants can use.
Weeds in the lawn can indicate what changes you need to make to grow healthy grass. Mow your lawn too low (shorter than one and one-half inches) and you encourage annual bluegrass, crabgrass and plantain. Low mowing can kill grass roots and invite the sunlightthat stimulates weed sprouting. Mowing higher encourages grass to develop deeper, drought-resistant roots.
Water too much or too little and you may find clover, crabgrass or annual bluegrass in your lawn. For most turf grasses, one deep weekly watering (about one inch) in the early morning is best. Poor drainage invites ground ivy, knotweed and plantains to take hold, but once your lawn has established a deep root system, you won't need to water as much and drainage may be less of an issue.
Napa County Master Gardeners are offering two upcoming activities to help you work with your weeds:
Weed ID: Join Napa County Master Gardeners on Wednesday, April 23, from 3 p.m. to 5 p.m., at Connolly Ranch (address below) in Napa for “Wednesday Walk About.” Master Gardeners will focus on weed identification in their demonstration garden. Materials will be available to take home for identifying weeds in your own yard.
Workshop:Join Napa County Master Gardeners for “What's That Weed? What Does It Tell Me? How Do I Control It?” on Thursday, April 24, from 6 p.m. to 7:30 p.m., in the University of California Cooperative Extension office (address below).Learn to identify some of the most common garden weeds and what they can tell you about your garden. Knowing what weeds you have can help you discover clues about your garden microclimates and soil conditions.Online registration (credit card only)Mail in registration (cash or check only)
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. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
Napa County Master Gardeners welcome the public to visit their demonstration garden at Connolly Ranch on Thursdays, from 10:00 a.m. until noon, except the last Thursday of the month. Connolly Ranch is at 3141 Browns Valley Road at Thompson Avenue in Napa. Enter on Thompson Avenue.