Home & Garden: Planning a winter garden in western Colorado
Free Press Gardening Columnist
Gardeners living in areas where the ground freezes often feel vegetables can only be planted during 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 can also 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.
Cool-season vegetables suggested for seeding in late fall and early winter include: Lettuce, peas, spinach, broccoli, Brussels sprouts, carrots, radish and cauliflower.
Even though potatoes are cold hardy like the preceding vegetables, planting potato tubers in late fall is not recommended as they often freeze and rot during the winter. 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. This planting of potatoes was in a raised bed with concrete blocks on the south and west side, which kept the soil from freezing and allowed the tubers to survive.
One tuber plant that does well when planted in early winter is the Jerusalem artichoke. Also called Canada potato and tuberous sunflower, this vegetable tolerates cold frozen soil — and for that reason is hard to eliminate once planted. It is very easy to miss some of the smaller tubers when the crop is dug in the fall resulting in a repeat crop year after 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 out produce expensive, store-bought transplants. Cool season crops seeded prior to or during the winter germinate in the spring based on soil and air temperature.
An excellent reason to plant cool-season vegetables listed above is their intolerance to hot summer weather. When seeded late in the spring these vegetables are more susceptible to disease problems than if planted in late fall/early winter or very early spring (February in our area). A prime example of a summer disease is the powdery mildew that attacks peas during hot weather. Peas harvested in the summer don’t have the sweet, snappy flavor of peas harvested in the cool of spring; I don’t think the peas harvested in the heat are even worth harvesting. 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 as well. When hot weather arrives spinach will bolt and their rounded fleshy leaves become arrow-shaped and have a distinctively bitter flavor as compared to spinach leaves harvest in the early spring.
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.
HOW TO DO IT
After the garden has been cleared of all dead non-decomposed plant material this fall, add compost and till it in. Or leave the dead debris on the garden as a mulch and skip the tilling. Mow the overgrown tomato, eggplant and other vegetable plants down and leave the debris in place on the garden. After you have done this task, mark the rows in preparation for seeding. Just before the ground freezes (or after if necessary) plant the seed of the desired cold-hardy vegetables in these pre-marked rows. Cover the seed with soil from the garden. If the ground is too frozen to use potting soil works well to cover the seed. Cover the seed as directed on the seed 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 adequate soil 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 of mulch. In areas where wind is a problem, mulch 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 to help carry the garden through until spring.
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 10 years if treated properly. Placing the seed 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.
To encourage even earlier germination than would normally occur, you could place a cold frame over selected portions of the garden in late January. A cold frame is nothing more than a bottomless box with a clear or translucent top. You can build your own or buy one. You will need to place a thermometer in the cold frames and use the temperature in the cold frame as a guide as to when to open and close the sash. You don’t want the inside of the cold frame to get excessively hot. The other option is to buy a cold frame with an automatic sash opener. You can also just buy an automatic openers and attach it to your home-made cold frame.
GJ Free Press columnist Dr. Curtis E. Swift is a retired horticulture agent with the Colorado State University Extension. Reach him at Curtis.Swift@alumni.colostate.edu, 970-778-7866 or check out his blog at http://SwiftsGardeningBlog.blogspot.com. He owns Swift Horticultural Consulting and High Altitude Lavender.
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