By Susanne von Rosenberg, UC Master Gardener of Napa County
January is a great time of year to plant strawberries in Napa Valley, regardless of online recommendations to plant them in the spring, late summer or early fall.
Strawberries come in three types: June bearing, day neutral and everbearing. June-bearing strawberries set one heavy crop in late spring, typically starting in mid-May in our area for the early varieties. They produce most of their berries in a window of 10 to 14 days, and they tolerate hot temperatures. June-bearing strawberries come in early-, mid-, and late-season varieties. The late-season varieties start fruiting about two weeks after the early varieties.
Day-neutral varieties will fruit as long as the day length is 12 hours or more and temperatures remain between 40°F and 90°F. Despite their name, everbearing strawberries will produce a fairly heavy crop in late spring and again in early fall. They may produce a third crop in mid-summer in mild summer areas.
Sources disagree about which type of strawberry plants produce the biggest berries. But unless you want large berries for decorative reasons, don't let size affect your choice as it has no correlation to flavor.
Many strawberry varieties do well in our area. In 2012, the Master Gardeners did a field trial of three varieties, and Albion (a day-neutral variety) performed best. Sequoia (an everbearing variety that can produce all season in mild climates) also did fairly well, but Quinault, a popular everbearing variety, performed poorly.
Other good day-neutral varieties include Seascape and Selva. The latter is notable for its large berries. Good June-bearing varieties include Chandler, Jewel, Camarosa and Ventana.
Not surprisingly, catalogs tend to describe all the varieties as having great flavor, so just experiment and see which you prefer. One source said Jewel had an “exotic tropical fruit flavor.” Camarosa and Chandler are said to produce large yields.
Everbearing varieties seem to be losing ground to day-neutral varieties. To make matters more confusing, a lot of catalogs and online sources use those terms interchangeably, although they clearly aren't the same.
Look for certified disease-free, bare-root plants from a local nursery. Big-box stores sometimes have six-packs of strawberry plants, but often with no indication of variety. Think twice about buying these as you won't know if they're suited to our climate, or when the plants will bear fruit.
Strawberry plants will produce the year you plant them and will typically have their best crop the following season. After that, production will decline. Expect to replant about every three years. You can grow your own new plants from runners. June-bearing plants will produce the most runners, whereas everbearing and day-neutral varieties put more of their energy into producing fruit.
If you don't want to grow replacement plants, cut off the runners because they take energy from fruit production. It's also best to cut off runners in the first year to help the plants get established. Leaving a few runners to fill bare spots is okay.
Strawberry plants need at least eight hours of sunlight a day. Don't plant them where you recently grew members of the Solanaceae family, such as tomatoes, eggplants, peppers and potatoes. All these plants are susceptible to verticillium wilt, a fungal disease. By rotating where you plant Solanaceae, you can keep the fungus from getting established in the soil.
Slugs and snails are the primary pests of strawberries. Pick them off by hand, or use an iron phosphate-based bait. These baits are non-toxic to other animals. Strawberries can also suffer from nutrient deficiencies. (I had an issue with lack of boron.) Check online sources if your berries look odd.
Plant your plants so that the crown (center growing point) is just above the soil level. Strawberries need regular water, especially during fruit-bearing season. Use drip irrigation with emitters at least two inches away from the plant to minimize the risk of fungal disease. Keep the soil moist—strawberries are shallow-rooted—but let the top of the plant dry out between waterings to avoid rot. Don't plant strawberries near irrigated lawn or where they might be watered by overhead sprinklers.
Strawberries like well-drained soil. Raised beds with 12 to 18 inches of soil are ideal, or mound up your garden soil to a depth of 6 to 8 inches. If you are growing strawberries in a container, be sure they have 12 inches of soil as well. Those special strawberry planter pots are attractive but often not that effective because they don't hold enough soil. Use them for growing annual herbs instead.
Strawberries do not need a lot of fertilizer. One application of a slow-release or organic fertilizer at planting time is adequate for the first season. Fertilize again in late summer or early fall for the following year.
Workshop: Napa County Master Gardeners will host a workshop on “Pruning and Plant ID” on Saturday, January 29, from 10 a..m. to noon at Las Flores Community Center, 4300 Linda Vista Avenue, Napa. Bring gloves and wear gardening attire for this hands-on workshop. To register: https://ucanr.edu/2022JanLasFloresLearningGardenPruning
Library Talk: Napa County Master Gardeners will give a talk on “Creative Cucurbits: Loofahs and More” on Thursday, February 3, from 7 pm to 8 pm. Save room in the garden for some crazy cucurbits and learn how to prepare them for your own use or as gifts. Register to receive the Zoom link at https://ucanr.edu/2022FebCucurbits.
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 https://napamg.ucanr.edu
January is perfect for assessing your collection of saved seeds and making plans for the next round of gardening. If you enjoy starting your own vegetables and annual flowers, order seeds from catalogs now to get them before you need them, at the end of January or early February.
My least favorite winter task is watering, but in this dry winter, we must water to keep plants healthy. Vegetable gardens planted in the fall with winter greens, broccoli, onions and garlic will not thrive unless watered.
Water vegetables when the top one to two inches of soil have dried out, and moisten the soil to a depth of 8 to 12 inches. Perennial plants that grow and bloom in winter, which includes most native plants, will also need regular watering. Plants that go mostly dormant in winter, such as roses and fruit trees, still need some water to stay healthy. And frost-tender plants like citrus need to be kept well-hydrated to help them fend off frost damage.
In our climate, January is historically the coldest month. However, we can hope that we will not be repeating December’s run of below-freezing nights. Be sure to protect tender plants when frost threatens.
If the rains do come, expect an increase in weed growth. Control weeds while they are small, hoeing or pulling them out. Whenever possible, use mulches to control weeds and conserve soil moisture. If you use organic mulches, the material will break down over time and improve your soil.
Insect pests tend to be less of a problem in cold weather, but I noticed that aphids on my cauliflower and broccoli survived December’s frigid temperatures. Control these plant-sucking pests by spraying them off with water. Vegetables tolerate a few aphids, but these insects seem to multiply quickly if not addressed early.
Deciduous fruit trees should be dormant now, with all leaves gone. Now is the time to prune and shape them. First remove all broken, diseased or dead wood, then look at the tree from all sides and tackle pruning for shape and for fruit. Different types of fruit trees require different amounts of pruning, so consult a knowledgeable tree source if you do not know how much growth to remove.
Winter is also the time to spray fruit trees to control pests. Copper-based fungicides control fungal diseases such as peach leaf curl and powdery mildew. Spray on a dry, wind-free day and be sure to follow all precautions on the product label. Dormant oil sprays can help control insect pests such as scale and mites by smothering their eggs. Delay spraying until close to bud break in late winter or early spring.
Nurseries have a good supply of bare-root fruit and shade trees now. Bare-root trees are an economical way to add to your orchard or beautify your landscape. Keep the roots moist after purchase and plant as soon as possible. When preparing the planting hole, do not amend the native soil too much. Add no more than 25 percent compost to the soil that covers the roots to encourage the roots to dig deeper for nutrients. Plant the crown of the tree higher than the soil surface to allow for settling over time and to keep the crown from being inundated with moisture during rainy periods. Mulch well, keeping the mulch four to six inches away from the trunk to prevent crown rot.
Bare-root choices also include roses, ornamental vines, artichokes, strawberries and asparagus. As you would for bare-root trees, keep the crown of the plant at or above soil level when planting.
Any vegetables you planted in fall are probably growing slowly now, but check them often for maturity and harvest as ready. These might include lettuces, parsnips, beets, carrots, cabbages, broccoli and radishes. You can get an early start on the spring planting season by sowing seeds now for kale, parsley, radishes and spinach. These crops can be direct-sown outdoors, while the brassicas (broccoli, cabbage, cauliflower) should be started indoors for transplanting next month.
Enjoy the slower pace of January gardening. And if you have any influence with the weather gods, have them send us some rain.
Workshop: Join Napa County Master Gardeners for a workshop on “Rose Pruning” on Saturday, January 18, from 10 a.m. to noon, at the University of California Cooperative Extension (address below). January is the best time to prune your roses. Come learn pruning techniques from a certified Rosarian. Bring your rose questions. Online registration (credit card only).Mail-in registration (cash or check only).
Napa County Master Gardeners welcome the public to visit their demonstration garden at Connolly Ranch on Thursdays, from 11:00 a.m. until 1 p.m., except the last Thursday of the month. Connolly Ranch is at 3141 Browns Valley Road at Thompson Avenue in Napa. Enter on Thompson Avenue.
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.