When To Plant Cabbage In Colorado

Knowing when to plant cabbage in Colorado is the first step to a successful harvest. Our unique climate, with its short springs and sudden frosts, makes timing absolutely critical for this cool-season favorite.

Get it right, and you’ll be rewarded with crisp, tightly packed heads. Get it wrong, and your plants might bolt to seed or struggle in the heat. This guide will walk you through the optimal schedule for both spring and fall planting, tailored to Colorado’s Front Range and mountain regions.

We’ll cover everything from seed starting dates to soil preparation. Let’s get your cabbage growing.

For most Colorado gardeners, you have two main planting windows: early spring and mid-summer for a fall harvest. The key is to avoid having your cabbage mature during the peak summer heat.

Spring Planting Schedule

Spring planting aims to get cabbage established in cool weather and harvested before the summer scorch. Here’s how to break it down:

Start Seeds Indoors: Begin your seeds about 6-8 weeks before your last average spring frost date. For Denver (last frost around May 5), this means starting seeds indoors in mid to late March.
Transplant Outdoors: Move your sturdy seedlings into the garden 2-4 weeks before that last frost date. Cabbage can handle a light freeze, so early April transplants are common. Always harden off your plants first.
Direct Seed Option: You can sow seeds directly in the garden as soon as the soil is workable, about 2-3 weeks before the last frost. This method is less reliable than transplants due to our erratic spring weather.

Fall Planting Schedule (Often the Best!)

Fall is an excellent time for cabbage in Colorado. Cooler autumn temperatures and fewer pests lead to sweeter, more tender heads. The trick is to work backwards from your first fall frost.

Calculate Your Dates: Find your average first fall frost date (Denver is around October 7).
Start Seeds Indoors: For a fall harvest, start seeds indoors in early to mid-June. This gives you transplants ready for the garden by mid-July.
Transplant Outdoors: Get your seedlings in the ground by late July. They’ll grow through the warm weeks of August and mature during the cool, perfect days of September and October.

Colorado’s Mountain Region Adjustments

If you garden above 7,000 feet, your season is shorter and cooler. Focus primarily on the spring planting window, but start seeds indoors even earlier—up to 10 weeks before your last frost. Use season extenders like cold frames. Fall planting is more challenging due to early frosts, but can be done with protection and very early-maturing varieties.

Choosing the Right Cabbage Variety

Selecting a variety suited to your planting season and Colorado’s climate improves your chances. Look for days-to-maturity on the seed packet.

For Spring: Choose fast-maturing varieties (under 70 days) to beat the heat, like ‘Fast Ball’ or ‘Gonzales’.
For Fall: You can use slower-maturing types (80+ days) since they thrive in cooling weather. Try classic storage cabbages like ‘Danish Ballhead’ or red varieties like ‘Ruby Perfection’.
All-Season Favorites: Reliable hybrids like ‘Cheers’ or ‘Stonehead’ perform well in both seasons and resist splitting.

Step-by-Step Planting Guide

Once your timing is set, follow these steps for healthy plants.

1. Prepare Your Soil

Cabbage needs fertile, well-draining soil. Colorado’s clay-heavy soil needs amending.

Work in 3-4 inches of compost or well-rotted manure.
Ensure a soil pH between 6.5 and 6.8.
Mix in a balanced organic fertilizer before planting to provide steady nutrients.

2. Planting Your Seedlings

Proper spacing is crucial for good head development.

Space plants 12-24 inches apart in rows that are 2-3 feet apart. Dense planting leads to smaller heads.
Plant seedlings slightly deeper than they were in their pots.
Water them in thoroughly with a starter fertilizer solution to reduce transplant shock.

3. Essential Care Tips

Consistent care prevents problems and encourages robust growth.

Watering: Provide 1-1.5 inches of water per week. Use drip irrigation or soaker hoses to keep leaves dry and prevent disease. Inconsistent watering can cause heads to split.
Fertilizing: Side-dress with a nitrogen-rich fertilizer when plants are about halfway to maturity. This gives them a needed boost.
Pest Control: Watch for cabbage worms and aphids. Use floating row covers as a physical barrier or apply organic controls like Bt (Bacillus thuringiensis) promptly.

Common Problems and Solutions

Even with good timing, you might face a few issues.

Bolting: If a plant sends up a flower stalk prematurely, it’s usually due to a sudden warm spell after cool weather. Solution: Stick to the planting dates and choose bolt-resistant varieties for spring.
Small or No Head Formation: Caused by overcrowding, poor soil nutrition, or excessive heat. Solution: Ensure proper spacing, fertile soil, and accurate planting times.
Pest Pressure: Cabbage loopers are common. Solution: Check undersides of leaves regularly and handpick, or use row covers from the day you plant.

Harvesting and Storing Your Cabbage

Harvest when heads feel firm and solid when you gently squeeze them. Use a sharp knife to cut the head from the base of the plant. For fall harvests, you can often leave them in the garden through several light frosts, which actually improves flavor.

Store unwashed heads in a cool, humid place like a refrigerator crisper drawer or root cellar. Properly stored, they can last for months.

FAQ: Planting Cabbage in Colorado

Can I plant cabbage in early summer in Colorado?

Planting in early June is usually to late for spring cabbage and to early for fall transplants. The mid-summer heat will stress them. It’s best to follow the spring or fall schedules outlined above.

What is the latest I can plant cabbage for a fall harvest?

You should aim to get transplants in the ground by the first week of August at the absolute latest. After that, they won’t have enough time to mature before a hard freeze. Using quick-maturing varieties can extend this deadline slightly.

How do I protect my cabbage from Colorado’s late spring snow?

Young, hardened-off cabbage plants can survive a light snow if it melts quickly. Have floating row covers, cloches, or even cardboard boxes ready to throw over them if a heavy, wet snow or hard freeze is forecasted. Remove covers once the weather moderates.

Can I grow cabbage in containers on my Colorado patio?

Yes! Choose a compact variety and a large container (at least 12 inches deep and wide). Use high-quality potting mix and be vigilant about watering, as containers dry out faster, especially in our dry air and sun.

Why are my cabbage leaves turning purple?

Purple tinges can be a sign of cold weather, which is harmless. However, if the weather is warm, it might indicate a phosphorus deficiency in the soil. Have your soil tested and amend as needed with a phosphate fertilizer or compost.

By following these timing guidelines and care tips, you can grow excellent cabbage in your Colorado garden. The effort is well worth it for the fresh, homegrown flavor you’ll enjoy in your meals.