Colorado’s high altitude and cool summers make late spring the perfect time to plant kale. The best time to plant kale in colorado is actually a narrow window that depends on your specific elevation and microclimate.
Kale loves cool weather. It gets sweeter after a light frost. But Colorado weather is unpredictable. You need a plan that works for your garden zone.
Most Colorado gardeners live in zones 4 through 6. Some mountain areas are zone 3. The Front Range and Western Slope have different planting calendars.
Let’s break down exactly when to plant kale in Colorado. We’ll cover spring planting, fall planting, and everything in between.
Best Time To Plant Kale In Colorado
The ideal window for spring kale planting in Colorado is mid-April to late May. This timing gives your kale cool soil and moderate air temperatures.
Kale seeds germinate best when soil temperatures are between 45°F and 75°F. Colorado soil warms up slowly in spring. Check your soil temperature with a simple thermometer.
For fall harvest, plant kale in late July to mid-August. Fall kale often tastes better because it matures during cooler weather. A light frost actually improves the flavor.
Here is a quick breakdown by Colorado region:
- Front Range (Denver, Boulder, Colorado Springs): Plant spring kale mid-April to mid-May. Plant fall kale early August.
- Western Slope (Grand Junction, Montrose): Plant spring kale early April to early May. Plant fall kale late July.
- High Mountains (Leadville, Breckenridge): Plant spring kale late May to mid-June. Plant fall kale mid-July.
- Southeast Plains (Pueblo, Lamar): Plant spring kale early April to early May. Plant fall kale late July.
Understanding Colorado’s Climate For Kale
Colorado has over 300 days of sunshine per year. That’s great for kale. But the state also has dramatic temperature swings.
Kale is a cold-hardy crop. It can survive temperatures down to 20°F. But young seedlings are more delicate. Protect them from late spring frosts.
Colorado’s low humidity helps prevent fungal diseases. Kale stays healthier here than in humid states. But you must water consistently.
Altitude affects growing conditions. Higher elevations have thinner air and more intense UV radiation. Kale may need partial shade in some mountain gardens.
Soil Preparation For Colorado Kale
Colorado soil is often clay-heavy or sandy. Neither is ideal for kale. You need to amend your soil before planting.
Kale prefers rich, well-draining soil with a pH between 6.0 and 7.5. Test your soil pH with a home kit. Most Colorado soil is alkaline.
Add organic matter like compost or aged manure. This improves drainage in clay soil and water retention in sandy soil. Mix in 2 to 4 inches of compost.
Kale is a heavy feeder. It needs nitrogen for leafy growth. Add a balanced fertilizer before planting. Blood meal or fish emulsion work well.
Choosing Kale Varieties For Colorado
Not all kale varieties perform equally in Colorado. Some handle temperature swings better than others.
Here are the best kale varieties for Colorado gardens:
- Lacinato (Dinosaur) Kale: Very cold-hardy. Tolerates light frost well. Good for both spring and fall planting.
- Red Russian Kale: Grows quickly. Has flat, fringed leaves. Sweetens after frost. Great for fall harvest.
- Winterbor Kale: Extremely cold-tolerant. Can survive winter in milder Colorado areas. Produces tender leaves.
- Starbor Kale: Compact variety. Good for containers. Handles heat better than most kales.
- Vates Blue Curled Kale: Dwarf variety. Very hardy. Produces for a long season.
Spring Planting Guide For Colorado Kale
Spring planting requires careful timing. Plant too early and frost kills your seedlings. Plant too late and summer heat makes kale bitter.
Start kale seeds indoors 4 to 6 weeks before your last frost date. Colorado’s last frost date varies by location. Denver’s average last frost is around May 5. Colorado Springs is May 10. Grand Junction is April 25.
Use seed starting mix in small pots. Plant seeds 1/4 inch deep. Keep soil moist but not waterlogged. Provide bright light once seedlings emerge.
Harden off seedlings before transplanting. This means gradually exposing them to outdoor conditions over 5 to 7 days. Start with a few hours of shade, then increase time and sun exposure.
Transplant seedlings outdoors when they have 4 to 6 true leaves. Space plants 12 to 18 inches apart. Rows should be 18 to 24 inches apart.
Water deeply after transplanting. Use row covers if frost is predicted. Floating row covers protect down to 28°F.
Direct Sowing Kale In Colorado Spring
You can also direct sow kale seeds in spring. This is simpler but takes longer. Seeds need consistent moisture to germinate.
Direct sow seeds 2 to 4 weeks before your last frost date. Soil temperature should be at least 45°F. Use a soil thermometer to check.
Sow seeds 1/4 to 1/2 inch deep. Space seeds 2 inches apart. Thin seedlings to 12 inches apart when they are 4 inches tall.
Keep soil moist during germination. Colorado spring winds dry out soil quickly. Water daily if needed. Use a gentle spray to avoid washing seeds away.
Direct sowing works best for fall planting. Spring direct sowing is riskier due to cold snaps.
Fall Planting Guide For Colorado Kale
Fall kale is often better than spring kale. Cool temperatures produce sweeter, more tender leaves. Frost improves flavor dramatically.
Plant fall kale 6 to 8 weeks before your first fall frost. Colorado’s first frost date ranges from mid-September to mid-October. Denver’s average first frost is October 10. Colorado Springs is September 28. Grand Junction is October 15.
For fall planting, direct sow seeds in late July or early August. This gives kale time to mature before hard frosts arrive.
Fall kale needs consistent watering. August in Colorado is hot and dry. Water deeply 2 to 3 times per week. Mulch around plants to retain moisture.
Fall-planted kale can often overwinter in milder Colorado areas. Plants go dormant in deep cold and resume growth in spring. This gives you an early harvest next year.
Protecting Kale From Colorado Weather
Colorado weather is extreme. Hail, wind, and sudden temperature drops can damage kale. Take protective measures.
Use row covers for frost protection. They add 4 to 8 degrees of warmth. Remove covers during the day if temperatures rise above 70°F.
Hail can shred kale leaves. Keep row covers or shade cloth handy during storm season. Hail nets are available at garden centers.
Wind dries out soil and damages plants. Plant kale in a sheltered location. Use windbreaks like fences or taller plants.
Mulch heavily around kale plants. Straw, grass clippings, or shredded leaves work well. Mulch keeps soil cool, retains moisture, and suppresses weeds.
Watering Kale In Colorado’s Dry Climate
Colorado is semi-arid. Annual precipitation is only 15 to 20 inches in most areas. Kale needs consistent watering to thrive.
Kale requires about 1 to 1.5 inches of water per week. More during hot, dry periods. Less during cool, cloudy weather.
Water at the base of plants. Avoid wetting leaves to prevent fungal issues. Drip irrigation is ideal. Soaker hoses also work well.
Water deeply and less frequently. This encourages deep root growth. Shallow watering leads to weak plants.
Check soil moisture by sticking your finger 2 inches into the soil. If it feels dry, water. If moist, wait a day.
Fertilizing Kale In Colorado
Kale grows quickly and needs regular feeding. Nitrogen is the most important nutrient for leafy growth.
Apply a balanced fertilizer at planting time. Use a 10-10-10 or similar formula. Follow package directions for application rates.
Side-dress with nitrogen fertilizer 3 to 4 weeks after transplanting. Blood meal, fish emulsion, or compost tea work well. Apply every 3 to 4 weeks during the growing season.
Avoid over-fertilizing. Too much nitrogen can make leaves tough and bitter. Follow recommended rates.
Organic options include compost, aged manure, and worm castings. These release nutrients slowly and improve soil structure.
Common Kale Problems In Colorado
Kale is generally easy to grow. But Colorado conditions can cause specific problems. Here are common issues and solutions.
Bolting happens when kale flowers and goes to seed. This occurs in response to heat and long days. Plant early or late to avoid summer heat. Choose bolt-resistant varieties.
Pests include aphids, cabbage worms, and flea beetles. Use row covers to exclude pests. Spray with neem oil or insecticidal soap if needed. Introduce beneficial insects like ladybugs.
Yellowing leaves often indicate nitrogen deficiency. Apply a nitrogen-rich fertilizer. Also check for overwatering or poor drainage.
Leaf tip burn can result from inconsistent watering. Maintain even soil moisture. Mulch helps regulate moisture levels.
Deer and rabbits love kale. Use fencing or repellents. Motion-activated sprinklers can deter animals.
Harvesting Kale In Colorado
Kale is ready to harvest 50 to 75 days after planting. Harvest leaves when they are about the size of your hand.
Pick outer leaves first. Leave the inner growing point intact. This allows continuous harvest for weeks or months.
Harvest in the morning when leaves are crisp. Leaves wilt quickly in Colorado’s dry air. Place harvested kale in a plastic bag in the refrigerator.
Kale tastes best after a light frost. The cold converts starches to sugars. Fall-harvested kale is noticeably sweeter.
You can harvest kale throughout winter in milder areas. Plants survive under snow. Leaves may be smaller but are very sweet.
Extending The Kale Season In Colorado
With some planning, you can harvest kale for 8 to 10 months in Colorado. Use season extension techniques.
Cold frames protect kale through winter. Build or buy a simple cold frame. Place it over kale plants in late fall. Open on sunny days to prevent overheating.
Low tunnels are another option. Use PVC hoops covered with greenhouse plastic. Ventilate on warm days. Low tunnels can extend harvest by 4 to 6 weeks.
Grow kale in containers. Move containers to sheltered locations during extreme weather. Containers also warm up faster in spring.
Succession planting ensures continuous harvest. Plant a new batch every 2 to 3 weeks. Stop planting 8 weeks before your first fall frost.
Frequently Asked Questions
Can I plant kale in Colorado in the summer?
Summer planting is possible but challenging. Heat makes kale bitter. If you plant in June or July, choose heat-tolerant varieties. Provide afternoon shade and consistent water.
How late can I plant kale in Colorado?
You can plant kale as late as early September for a winter harvest. Use cold frames or row covers. Plants will grow slowly but produce sweet leaves through winter.
Does kale need full sun in Colorado?
Kale prefers full sun but tolerates partial shade. In Colorado’s intense sun, afternoon shade can prevent leaf scorch. Six hours of direct sun is sufficient.
Can kale survive Colorado winter?
Yes, many kale varieties survive Colorado winter. Plants go dormant in deep cold. They resume growth in spring. Mulch heavily and use row covers for best results.
What is the best kale variety for Colorado beginners?
Lacinato kale is the best choice for beginners. It is very cold-hardy, disease-resistant, and produces tender leaves. It grows well in both spring and fall.
Final Tips For Colorado Kale Success
Start small. Plant a few kale plants your first season. Learn how they respond to your specific location.
Keep a garden journal. Note planting dates, weather conditions, and harvest times. This helps you refine your timing each year.
Join a local gardening group. Colorado gardeners share valuable advice for your specific area. Extension offices also provide region-specific information.
Kale is one of the most rewarding crops for Colorado gardens. It thrives in cool weather, tolerates frost, and provides nutritious leaves for months.
With proper timing and care, you can enjoy fresh kale from your Colorado garden from spring through winter. The key is knowing your local frost dates and planting accordingly.
Remember that microclimates matter. Your garden may be warmer or cooler than the official zone. Observe your own conditions and adjust planting times as needed.
Kale is forgiving. Even if you plant at the wrong time, you will likely get some harvest. Learn from each season and improve next year.
Start preparing your soil now. Check your frost dates. Choose your favorite varieties. Colorado kale is worth the effort.