Regional guide

Colorado High-Elevation Mountain Vegetable Garden

CSU Extension mountain vegetable guide for Colorado gardeners over 7,500 feet who need short-season, frost-aware, cool-season planning.

Climate signals

• CSU Extension defines high elevation or mountain vegetable gardening in Colorado as anything over 7,500 feet.
• The source gives the Gilpin County Extension office at 9,300 feet as an example with a June 10 average last frost and a September 15 average first frost.
• Many Colorado mountain sites can have fewer than 90 frost-free days, and lower-elevation valleys can be cooler than surrounding hillsides because cold air sinks at night.
• Cool-season vegetables are the easiest and most productive crops for mountain gardens.
• Warm-season vegetables such as tomatoes, corn, winter squash, beans, cucumbers, melons, peppers, eggplant, and okra often lack enough growing degree units; bush beans and summer squash are the warm-season crops most likely to succeed.

Planning notes

• Choose varieties with the least number of days to harvest because shorter-season selections require fewer GDUs; the source warns that listed maturity days may take longer in mountain conditions.
• Use a site with six to eight hours of full sun when possible, while four to six hours can be enough for leafy greens; a south-facing, slightly sloped area is best for warming soils in spring.
• Floating row cover is useful in mountain gardens because it can provide frost protection down to about 24 F, reduce drying winds, and help hold moisture.
• Direct-seed frost-tolerant plants such as kale, kohlrabi, lettuce, spinach, turnips, chard, mustard, beets, carrots, cabbage, endive, peas, and radish four weeks before the last frost when conditions allow.
• A soil thermometer is more accurate than frost dates alone; the source says to plant frost-tolerant crops when soil 6 inches deep is 40 F at 8:00 a.m. and to wait if the ground is frozen or snowy.
• Start longer-season crops such as broccoli, cauliflower, leeks, and Brussels sprouts indoors 6 to 8 weeks before the last frost and plant them out two weeks before the last frost after hardening off.
• Treat beans as experimental warm-season crops for mountain gardens and plant them after all danger of frost has passed; avoid using the difficult warm-season crop list as mountain priority recommendations.
• Because many mountain gardens have only one cool season, plant smaller amounts every two weeks for succession instead of planting every bed as soon as the ground thaws.
• Use block planting to save space and water, keeping blocks no wider than 3 to 4 feet so they can be tended without stepping into the bed.
• Check moisture instead of watering by a fixed schedule; irrigate when the top 2 to 4 inches of soil is dry to the touch.
• For season extension, floating row covers can add a couple weeks on either side of the season, and plastic-covered low tunnels can add about a month at either end when managed and ventilated.
• Use these priority catalog links as crop-level examples for CSU's mountain crop groups, not as Colorado mountain cultivar recommendations.

Catalog crop examples

These catalog entries match crops covered by the regional timing source; variety-specific details remain tied to each seed entry's own source.

• Black Seeded Simpson Lettuce Vegetable · Cool · 45 days
• Astro Arugula Vegetable · Cool · 35 days
• Lacinato Kale Vegetable · Cool · 60 days
• Bloomsdale Spinach Vegetable · Cool · 42 days
• Bright Lights Swiss Chard Vegetable · Shoulder · 55 days
• Georgia Southern Collards Vegetable · Cool · 65 days
• Golden Acre Cabbage Vegetable · Cool · 64 days
• Green Curled Endive Vegetable · Cool · 85 days
• Vit Mache Corn Salad Vegetable · Cool · 50 days
• Danvers 126 Carrot Vegetable · Shoulder · 70 days
• Detroit Dark Red Beet Vegetable · Cool · 58 days
• French Breakfast Radish Vegetable · Cool · 28 days
• Purple Top White Globe Turnip Vegetable · Cool · 55 days
• Early White Vienna Kohlrabi Vegetable · Cool · 55 days
• American Purple Top Rutabaga Vegetable · Cool · 90 days
• American Flag Leek Vegetable · Cool · 120 days
• Sugar Snap Pea Vegetable · Cool · 62 days
• Waltham 29 Broccoli Vegetable · Cool · 74 days
• Snowball Y Cauliflower Vegetable · Cool · 70 days
• Long Island Improved Brussels Sprouts Vegetable · Cool · 100 days
• Italian Flat Leaf Parsley Herb · Shoulder · 75 days
• Bouquet Dill Herb · Shoulder · 55 days
• Common Borage Herb · Warm · 60 days
• Common Chives Herb · Cool · 80 days
• Provider Bush Bean Vegetable · Warm · 50 days

Related regional guides

• Colorado Front Range and High Plains Garden A soil-temperature-first guide for dry, variable spring conditions, fast cool-season windows, and tender crops that need reliably warm weather.
• Colorado Front Range Container Vegetable Garden CSU Extension container vegetable guide for Front Range gardeners balancing container size, water, fertility, sun, and frost timing.

Source: CSU Extension vegetable gardening in the mountains