Gardening in the mountains is a challenging endeavor, particularly above 7500 feet in elevation. Contributing factors include high-intensity sunlight, low humidity, cool nights, a short growing season, drying winds, steep slopes, poor soil quality, and wildlife. The good news? Most of these challenges can be overcome with proper preparation. Colorado State University offers some fantastic tips and tricks for tackling a personal garden in the mountains. We also consulted our neighbor Jason Rademacher, a professional landscaper, for valuable insight.
Evaluate your desired site. If possible, choose a location that already supports plant life (grass, wildflowers, or even weeds). Aspen groves are ideal for many plants. Increase the organic content of the soil where it’s rocky and doesn’t have much-existing vegetation.
There are two major types of soil in this area. One is light-colored decomposed granite, which is what we tend to have in Glen Haven. This soil type is high in most nutrients except nitrogen. Decomposed granite is low in organic matter, dries out quickly, and doesn’t absorb heat well. According to Jason, this soil is pretty easy to work once it’s been amended. It does require a bit more watering, which he accomplishes with a drip system and sprinkler heads. Adding mulch to your garden can help to extend the time between waterings from every other day to a once per week schedule.
The other type of soil is clay. Clay is high in nutrients as well, but it has poor drainage. Jason says clay is a lot more common down in Greeley, and it comes with its own challenges. Native plants are often adapted to leaner soils, but in general, it’s good to add organic matter to mountain soil. If your soil is clay, consider adding only a small quantity of amended soil as salt can build-up due to the poor drainage typical of this soil type. Otherwise, add 2-3” or three cubic yards per 1000 square feet of garden space of one of the following: alfalfa pellets, compost, or aged manure to a depth of 6-12”. Avoid Colorado mountain peat as it’s a non-renewable resource and has too fine a texture.
Raised beds can solve many problems for mountain growers. Using a good, weed-free soil will warm faster in springtime. Using a hardware cloth at the base of the bed before adding soil will help protect plants from burrowing rodents. Jason adds a wire mesh to the base of his raised beds to keep out ground squirrels, mice, voles, and moles (see picture on page 14). Jason’s leech field is collocated with his garden, necessitating raised beds for all edible plants.
Exploit and create microclimates when possible to improve your garden’s health. Full sun or southern exposure will have a longer, warmer growing season. Also, close proximity to rock formations and walls provides the benefit of thermal mass which can raise winter temperatures of soil. Planting in a location with a reliable blanket of snow in winter ensures insulation that allows plants to overwinter. Another climate concern is strong winds that cause plants to dry out. To combat this effect, consider a wind barrier of fences, trees, or shrubs. Jason is adding a greenhouse to his garden. This building will provide both a windbreak and an insulating mass that will benefit the rest of the garden for the entire year. Lastly, airflow at night drains down to low spots meaning cold overnight temperatures for plants in property dips.
Plant choice makes a great difference in the success of your mountain garden. Plants with smaller leaves often require less water and experience less damage from hail. Late-blooming plants or plants that are heat lovers will likely not bloom before the first frost. In general, it’s best to choose plants that are hardy to zones 2-4. According to Jason, there are many plants that can be planted with success in Glen Haven. He has a great variety of flowers growing around his house from peonies and poppies to lilies and hyacinth and hollyhocks (which love this area!). He grows herbs, lavender, and vegetables from tomatoes, zucchini, cucumbers, and squash - not to mention berries and rhubarb, in his raised beds. Jason expressed some concern about growing corn as it has to be planted in the ground and can’t be started indoors, but he located a varietal out of Montana (where they have a similarly short growing season) that he’s eager to try this year. Another tell-tale sign that something will grow well in the area is looking to see what others are growing in their gardens. Jason said he planted a couple of apple trees after seeing that they grew well at a couple of other cabins on North Fork Road.
Low temperatures are only one factor in how a plant will overwinter. Other factors include length of days, sources of plant material, temperature patterns, rapid temperature changes, soil moisture, wind and sun exposure, and carbohydrate reserves. Native plants fare the best as they have already adapted to the harsh conditions of mountain climate.
The best time to plant is immediately after the last frost or during the rainy season. Jason recommends starting the growing process indoors in March or April and moving outdoors around June, or once there doesn’t appear to be any more snow in the forecast. If plants are purchased at lower elevations, reduce the amount of water, and increase exposure to outdoor conditions for two weeks prior to planting. The box pictured above is how Jason ‘hardens’ plants (gets them accustomed to the harsh sunshine here in the mountains). He places his plants in the box for a couple of hours per day for a week prior to transplanting outside. Plants should be watered on the day planted and mulched to help retain moisture! Covering crops with plastic covers or in a greenhouse will help to extend the growing season. It also helps to protect crops in the event of a hailstorm, which would likely kill everything you’d planted. A heated greenhouse could extend the growing season to be year-round. Jason would be an excellent resource if you’re interested in building a greenhouse on your property. He is a wealth of information!
While nothing is foolproof with wildlife, most avoid plants that are aromatic, have prickles or spines, tough leathery leaves. Fences are another preventive measure that locals employ, as well as the wire mesh base to raised beds mentioned earlier.
For additional information on mountain gardening, reference extension.colostate.edu or go by and talk with Jason Rademacher on North Fork Road!