Gardening can be done all year long, even in the dead of winter. But gardening in the winter becomes tricky when a warm spell occurs and prompts plants to sprout early, leaving them vulnerable to the next frost. During these times, it's important to take measures to protect your orchard or garden from blooming and ruining potential fruits and vegetables.
One such measure to protect the green tips from frost is to cover them with an inch or two of lightweight mulch, such as leaves. If a deep freeze does strike the foliage of bulbs and other plants, it probably will only harm the leaves and not the flowers, which are not likely to have emerged yet. Bulb plants should bloom on time, even if their leaves are discolored or shriveled.
It's important not to walk on lawns and garden beds during these warm spells, much less start digging. Soil that is beginning to thaw is likely saturated with water and can't drain well, because there is a layer of frozen soil underneath. Walking on wet soil can compact it, squeezing the soil particles together, so no air or water can flow between them. That causes big problems for plant roots.
Brad Julian, director of merchandising at Lowe's, said the range and variety of what you can grow in the winter is much narrower, so your winter garden should be about one-third the size of your summer garden. However, there are lots of cool-climate-loving vegetables that have better flavor and texture when grown in winter than during the heat of spring or summer. They include such greens as arugula, spinach, collards, lettuce, Swiss chard, mustard and kale; such root crops as like carrots, beets, onions and radishes; brassicas, including broccoli, cauliflower and cabbage; and legumes, such as fava beans and peas. Which crops to grow and the timing of planting will vary by location, but Lowe's has a website with garden plans, articles, videos and special tips for your region.
According to Julian, some tips on preparing a winter garden include preparing beds in early fall when the soil is easier to work with, watering your garden sparingly and covering them before the first frost. Sheets, blankets and floating row covers are the simplest ways to protect plants still growing in late fall. Simply toss covers over plants at night and remove them the next day, so the sun can warm the soil to carry plants through the next cold night. These covers work best when the fabric stays dry overnight.
Because air and soil temperature control growth of plants, temperature fluctuations in the winter can actually be more of a threat than the cold. Plants harden, meaning they develop winter hardiness and become dormant, and become able to tolerate cold weather as winter approaches. However, if there is a cold snap before the plant has adapted or if it is not allowed to harden off, tender growth can be damaged. And just as a prolonged warm spell can initiate new growth in a plant and make it susceptible to damage when cold returns, if there is unseasonably cold weather after the plant has begun normal spring growth, new growth and expanding buds can be damaged.
Sunscald can be a problem on thin-barked or newly planted trees. Cells become active when heated by the sun and are then killed as temperatures drop below freezing. Usually occurring on the south or southwest side of the trunk, sunscald can appear as sunken or discolored bark. Alternate periods of warming and freezing can also cause the bark to split. And warm temperatures along with wind can cause evergreen foliage to lose moisture.
The best way to go about building a winter garden is to choose plants that are winter hardy in your area. Careful plant placement is also important. Some plants require drier soil with excellent drainage in winter. Broadleaf evergreens do best in sheltered areas protected from winter wind.
Again, mulch is key. The goal is not to keep the soil warm but to keep it uniformly cold all winter. This can help prevent frost heaving as well as unwanted growth during unseasonably warm winter weather. Along with shredded leaves, weed-free straw and evergreen boughs are good choices, because they are light bulky materials that will not compact.
Mulch should not be applied until the plant is dormant, the ground has partially frozen and temperatures are consistently below freezing. This is usually not until the end of November or later. But be sure to keep mulch away from the trunks of woody plants and stems or crowns of perennials. Mulch can hold unwanted moisture and provide cover for rodents.