How to Grow Vegetables, Flowers, Shrubs, and More in Colorado
High-altitude growing seasons are short and sweet. The air is dry, and the sun can be harsh. All of this means would-be gardeners have to pay extra attention to the length of time it takes to grow flowers and vegetables, as well as to water requirements. Some vendors stock seeds that are engineered to withstand the particular challenges of growing plants at high-elevations. But usually, both for successful mountain vegetable gardens and ornamental gardens, it takes more than a solid seed and a lot of hope to keep things growing well.
How to Grow Vegetables at High Altitude
Raised beds warm up faster than ground-soil and may add a week or two to your growing season. But if you’re planting in the ground, and your soil isn’t too damp, you may want to spread a black plastic tarp over your planting area, to help warm it up before you put seeds in the ground. It your soil needs to dry out from a particularly heavy snow load or spring flood, skip the plastic, since it could slow the drying process.
Growing from Seeds
Plant your seeds in small troughs, which guard against wind and help keep them warmer. And if an unexpected frost hits but the temperatures climb before freezing prior to sunrise, you may be able to save your plants by watering just their bases.
Remember, mulch is your friend. Mulch helps keep seedlings warm.
Choose high-elevation seed strains that mature quickly. The key is to know the average length of your growing season, and choose seeds with a quick “days-to-harvest” rating. If you’re in Boulder, your growing season is about 150 days. But mountain towns often have growing seasons of less than 50 days. For every 1,000 feet gain in elevation, you lose about 3.5 degrees in temperature, with the exception being that valleys are often cooler than hillsides.
Frost-tolerant seeds can usually be planted four weeks before the projected last frost. But if there is still a big snow-pack or the ground is still frozen, it’s better to wait. Depending on how long a plant takes to grow, you can start it inside eight to four weeks before the last frost date, and relocate it outside when temps rise.
Vegetables to Consider Growing
Some vegetables that do well at high elevations include:
- Root varieties (carrots, parsnips, turnips, radishes, beets)
- Leafy greens
You can also grow vegetables that require longer growing seasons, you just have to take some extra steps. You can start your seeds indoors and protect your outdoor plants from the elements at the start and end of their growing season. Peppers, summer squash, eggplant, and tomato fare better if they’re planted indoors first, in pots, then moved outside once the frost-danger has passed. But don’t just move your plants from indoors to the ground. Slowly acclimate them to harsher temps by moving them outside for a few hours each day, for a couple of weeks prior to outdoor planting.
Choose Your Site Carefully
Zone maps are helpful, but high-elevation gardeners need to consider the qualities of their own unique site. Does your yard slope to the east, where it gets only morning sun, or does it face south, where you’ll get good sun all day? If it’s north-facing, you may be out of luck when it comes to vegetable-gardening, but some low-light ornamental plants may do well. It may be helpful to keep a gardening journal, recording which plants fared well, which didn’t, and first and last frost days from year to year.
Watch out for common pests, such as grasshoppers, cabbageworm, root maggots, cut worms and aphids. Releasing beneficial insects, such as ladybugs, can help guard against aphids. Neem powder and other organic pesticides may also be helpful.
Growing Ornamentals at High Elevation
Choose your plants carefully, and plant in late spring or early summer. Colorado State offers this list of trees and shrubs that grow well in mountain areas, and another list of flowers. Choosing native plants may be the key to successful landscaping, and as with vegetables, for successfully flower growth, you may have to add organic material to your soil.
Other Gardening Tips
First off, watering: you don’t want to overwater when it’s too cold, and freeze your plants’ roots, but you also don’t want to let the root-balls dry out. Water anytime the temperatures are above freezing, and the top 2-4 inches of soil gets dry. Here’s a basic guide to soil types and their water requirements.
Choose to plant in sites that get 6-8 hours of sunlight, if you can. If you’re planting vegetables, install windbreaks or use stationary walls and your own house as a windbreak. Planting directly beside your house allows plants to benefit from the heat your house emits. Floating row covers will also help protect your veggies from frost and wind and give you an extra few weeks of growing season.
Test your soil with Colorado State University. Often, high country soil is too alkaline, too sandy, or lacking in nutrients. You will probably need to add organic material, such as compost, aged manure, wood chips, pine needles, and leaves.
Cultivating fauna thousands of feet above sea-level is tough, but it can be done! And if you run into problems, you can always give your local master gardener a call. Good luck and happy growing!
Insure your home garden with a policy from Colorado Farm Bureau Insurance. To learn more, contact a local agent.