Garden Talk column: Get your garden going earlier with frost covers and hoop houses
Thinking about gardening? Love to see vegetables popping up? Don’t let the snow put you off! In fact, there are many vegetables you can start growing right now, at high altitude, even when it is still snowing in May.
You’ve got to love spring in the Rockies. It seems almost every other year we get a late snow in May or even June. Many of you may think this would make a vegetable garden impossible, but not so. In fact, there are many vegetables that don’t mind a little snow and frost and even thrive in the cooler temperatures of spring.
Growing vegetables in the colder climate of the Vail Valley can be a greatly enhanced with garden covers such as hoop houses and cold frames and frost cloths. Garden covers allow you to manage the temperature of your garden soil in the early spring and later in the fall.
The first thing to know is which vegetables do well, or at least manage, at the cooler temperatures of high altitudes in central Colorado. Most leafy greens can grow well in daytime temperatures that are at least above 45 degrees and will survive nighttime temperatures down to 25 degrees. Ordering your seeds online from a grower that selects for cold-tolerant varieties, such as http://www.bestcoolseeds.com in Alaska, will greatly increase their hardiness. Most big seed companies such as Burpee, that you see at Home Depot, are bred in Indiana in a warmer climate.
With the right vegetable seeds, the objective is then to manage the temperatures in your garden area and maintain them near or above freezing at night and above 45 degrees during the day. This is done mainly with garden covers such as frost covers — light cloths and hoop houses, which are mini-greenhouses that anyone can set up in an hour.
Hoop houses are cheap and easy to assemble. There are several kits available (see http://www.growerssupply.com), or the pieces are easy to put together from the hardware store. When combined with frost covers, they can maintain a garden area 5 degrees to 10 degrees above the outside air temperature. So even if the night gets down to 20 degrees, your garden will probably stay above freezing.
As soon as the sun shines the next day, the hoop houses need to be vented — because they can quickly warm up over 80 degrees — and your seeds will continue growing happily. As the season finally warms up and the last frost is past (around June 1, depending on your elevation), you can remove the hoop house and frost cover, and the vegetables will be well on their way toward harvest.
Our local climates around central Colorado are strongly linked to your individual elevation. A garden in East Vail will have a somewhat different experience than a garden in Eagle, 2,000 feet lower and often 10 degrees warmer. So the problem becomes one of managing your own local microclimate.
This system works with cold-tolerant vegetable varieties but can also pre-warm your garden for warm-season veggies, such as beans and tomatoes. Most of the leafy greens are very cold tolerant, starting with spinach, chard, kale, bok choy, onion, radish, some lettuce and parsley. With some protection, these can be planted after April 1, when the nights are mostly above 25 degrees.
As the nights get consistently above 25 degrees or 30 degrees, you can plant carrots, peas, potatoes, beets, turnips and cabbage. When the nights are mostly above 40 degrees, you can remove all protections and these will grow fine with at least six to eight hours of sunlight per day and plenty of water. The rest of the vegetables — the warm-season veggies — must wait until after June 1 to plant (again, depending on your elevation), when the nights are always above 40 degrees. In higher elevations, you will probably need to employ garden covers for much of the summer for some of the warm veggies.
Learn more about high-altitude gardening, plus many other tips such as how to improve your composting and build a healthy soil and how it will help build a more sustainable community, in my High Altitude Gardening class at Colorado Mountain College in Edwards in May. For more information or to register, call Colorado Mountain College at 970-569-2900.
Lori Russell is a local gardener, professional landscaper and teacher of high-altitude techniques. She lives and gardens in Eagle. Contact her at 970-328-5324.