High-altitude gardens need warm covers
Vail, CO Colorado
Thinking about gardening? Love to see some vegetables popping up, but the snow has 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 gotta love spring in the Rockies. It seems almost every other year, we get a late snowfall sometime in May or even June. Many of you may think this makes the idea of a vegetable garden obsolete, 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.
High-altitude gardening presents many challenges to the would-be gardener, but learning the right types of vegetables and some “cold management” techniques can bring a prolific vegetable harvest to almost anyone, at any elevation, with some considerations and limitations.
The first thing to know is which vegetables do well, or at least manage at the cooler temperatures of high altitudes in Eagle County. Most leafy greens can grow in daytime temps that are at least above 45 degrees and will survive nighttime temps down to 25.
With the right vegetable seeds, the objective is then to manage the temperatures in your garden area, and maintain them above freezing at night, and above 45 in the day. This is done mainly with garden covers like “frost cover,” a light cloth, 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, or the pieces are easy to put together from the hardware store. When combined with frost covers, they can keep a garden area five to 10 degrees above the outside air temp. 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 to 80 degrees, and your seeds will continue growing happily.
As the season finally warms up and the last frost has passed (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 Eagle County are strongly linked to your individual elevation. A garden in East Vail will have a somewhat different experience than a garden in Avon, 1,000 feet lower, and often 10 degrees warmer. So the problem becomes one of managing your own local micro-climate.
This system will only work with “cold tolerant” vegetable varieties. Most of the leafy greens are very cold tolerant, starting with spinach, chard, kale, mache, onion, radish, some lettuce and parsley. With some protection, these can be planted after May 1, when the nights are mostly above 25 degrees.
As the nights get consistently above 25 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 a 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. In higher elevations, you will probably need to employ garden covers for much of the summer for some of the warm veggies.
We will learn more about high-altitude gardening, plus many other tips like how to improve your composting and build a healthy soil and how it will help build a more sustainable community, in my organic gardening class at Colorado Mountain College, Edwards campus, starting Tuesday, and again May 16. Call CMC at 970-569-2900 for more info on course 58205. Or call Lori Russell at 970-328-5324.
Lori Russell is a local gardener and teacher of high-altitude gardening techniques at Colorado Mountain College.
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