Winter Gardening: Planting Vegetables in Early Winter for an Early Spring Crop
Curtis Swift, Ph.D., Colorado State University Extension
Gardeners living in areas where the ground freezes often feel vegetables can only be planted during the frost-free periods. However, some cold hardy vegetables can be planted up to six weeks prior to the average last killing spring frost. Many of these vegetables also can be planted late in the fall and into the winter months even when the ground is frozen. These vegetables will often be ready for harvest a month or two before your neighbors even think about planting their gardens.
The cool season vegetables suggested for late fall and early winter planting include:
- Brussel sprouts
Potatoes and other tuber and root vegetables may freeze and rot during the winter and are not recommended for late fall, early winter planting. Having said that, however, I have had potatoes grow from tubers I missed one year only to enjoy a harvest from those same potatoes the following year.
Volunteer tomato, squash, pumpkin and several other warm season crops frequently germinate early in the spring from fruit left in the garden the previous fall. These 'naturally' seeded vegetables harden off quickly in the spring and are remarkably capable of withstanding freezing temperatures. They often outproduce expensive store-bought transplants. Cool season crops seeded prior to or during the winter germinate in the spring based on soil and air temperature not the whim and fancy of the gardener.
Cool-season vegetables seeded late in the spring are more susceptible to disease problems than if planted in late fall/early winter or very early in the spring. A prime example is the powdery mildew that attacks peas during hot weather. Peas also yellow during these hot periods. Lettuce, spinach and chinese cabbage planted too late in the spring often bolt (form a seed stalk) when hot weather arrives. Radish planted during the heat will typically bolt instead of developing an enlarged root.
Planting in the fall and early winter just before the ground freezes allows these cold-hardy vegetables the opportunity to develop early in the spring when soil and air temperatures are ideal for this category of vegetable.
After the garden has been cleared of all dead non-decomposed plant material in the fall, add compost and till it in. Then mark the rows in preparation for seeding. Just before the ground freezes (or after if necessary) seed the desired cold-hardy vegetables in the premarked rows and cover the seed with soil from the garden. If the ground is frozen use potting soil to cover the seed. Cover the seed as directed on the package.
A layer of straw or hay mulch or even shredded leaves (as long as they do not pack down) will help keep the ground frozen and maintain moisture through the winter. A good inch (2.5 cm) of mulch is sufficient. Even small seedlings like carrots will come through an inch of mulch. The mulch will settle by spring creating about one-half inch (1.75 cm) of mulch. In areas where wind is a problem, mluch can be held in place with chicken wire or boughs broken from used Christmas trees. After the mulch is in place, soak the seeded area to provide sufficient moisture for germination.
Most nurseries and garden centers return or discard unsold seed in the fall. Some nurseries, however, purchase seed in bulk and then repackage it for sale the following year. Many dealers should still have seed available and if you had seed left over from last year, use it. It should still be good since vegetable and flower seed will store at room temperature for at least a year without significant loss of germination. Vegetable seed can be stored up to ten years if treated properly. Seeding closer than normal compensates for any reduced germination even when seed is several years old. Seedlings can always be thinned if more seed germinates than needed.
Updated November 24, 2010