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  • Napa Valley Marketplace Magazine

Winter Gardening

by Jane Callier, UC Master Gardener

A wet El Niño would be abundantly welcome and would bring great peace of mind. A well-watered plant is better equipped to withstand cold weather, and it’s time to start thinking about frost protection for sensitive plants. A priority for most gardeners is to protect their citrus trees. Siting plants according to the best, local microclimate available is a valuable boost to success in growing them. The sun is further south in the winter time, so frost-sensitive plants such as citrus benefit from a warmer, sunny, southern exposure. Other microclimate factors affecting heat retention are plants or fences that work as windbreaks, proximity to walls or a swimming pool that retains heat. It can be a matter of the only one or two degrees this protection offers that might determine whether 20% or 80% of your fruit freezes during a cold snap.

Fall is the best time to plant perennials. They will establish their roots and be ready to grow in the spring and more able to withstand the oncoming heat of summer. Selecting plants that are suited to California’s summer; dry, Mediterranean climate are the best candidates. Also, select plants with the goal of providing pollinators with year-round pollen and nectar. Some very easy-to-grow and easy-to-care–for, “bulletproof” plants, that meet both of these qualities are in the salvia family. Consider ‘Hot Lips,’ a plant that is always smiling, or ‘Black and Blue’ with its dramatic, black calyces (the part that hold the petals). They bloom from early spring until very late in the fall and the bees seem to be dizzy with happiness gathering their nectar. Salvia is a huge plant genus, with an almost–unlimited, color palette that will suit every taste. For pollinators still active in the dead of winter, some flowering plants are clover, often grown as a cover crop, camellia, manzanita, flowering quince, flowering currant and witch hazel.

Intrepid gardeners might also try a winter daphne. The daphne has a well-earned reputation of being finicky to grow, but if it’s successful it will be one of the most cherished plants in the winter garden. Their out-of-this-world fragrance is discernable many feet away from the plant. In the best of conditions it is a relatively short-lived plant, rarely lasting more than 8 years. Winter daphne has been described as “at least having the decency to usually die quickly instead of lingering for years.”

A garden landscape changes over time, and maybe some plants need to be transplanted to a more suitable site. For example, maybe a neighbor’s tree has grown too large and now shades plants that need to be in the sun. If plants aren’t too large to move, a transplant shovel that tapers to a narrow blade can be used for precise digging around the intended candidate without disturbing neighboring plants. Fall is the perfect time to divide and transplant perennials. Dividing a large perennial will reinvigorate the plant. In general, spring-blooming plants should be divided in the fall, and fall-blooming plants should be divided in the spring. Keep your transplants cool and moist.

It’s too late to start winter vegetables from seed, but you can try starts that are still available at nurseries. Harvest dates depend on weather and continue until hot weather comes. Warm soil conditions favor growth, and Napa County has had a very warm fall. When frost comes, it’s welcome in crops like kale, bringing out its sweetness. When the temperature drops too far, growth will stop until the weather warms. Chard can be planted any time. Garlic, shallots, leeks and onions can be planted in November, and spinach can be planted from September through April.

Plant some bulbs for spring bloom. Prepackaged bulbs are less expensive, but they are usually smaller and may produce less reliable blooms. Instead, choose heavy, dense bulbs with no decay, mold or fungus. Many gardeners in mild climates practice “pre-chilling” such bulbs as crocus, hyacinth and tulips in order to produce longer stems and better flowers. Tests done in Northern California by Sunset magazine with the UC Master Gardeners showed some surprising results. Pre-chilling these bulbs produced normal blooms and very little difference in height. Chilling is optional for Bay Area gardeners. For best selection, now is the time to place orders for dahlia tubers. Many popular varieties sell out quickly, and growers can only predict the number of tubers that a plant will produce.

Check the UC Master Gardeners of Napa Valley website: for more gardening resources, including A Month By Month Guide to Gardening in the Napa County.


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