When to Plant Kohlrabi in Colorado (2026 Guide)
Kohlrabi is a unique vegetable that combines the flavor of broccoli with the distinct appearance of a bulbous stem. Popular in many cuisines, this brassica is not only delicious but also easy to grow. Understanding when to plant kohlrabi in Colorado is essential, especially considering the varying frost dates across zones. For example, residents of Zone 5b can expect their last spring frost around May 5.
The different cities in Colorado present unique growing conditions based on their USDA hardiness zones. In Zone 5a, for instance, the last frost date is May 17, which can impact your planting timelines. While kohlrabi is resilient to frost, knowing these dates allows you to optimize your planting for the best possible yield. For growers in Zone 6a like Grand Junction, the last frost occurs even earlier, on April 25, extending your planting season.
From early spring sowing to late summer harvest, kohlrabi is a versatile crop that thrives in Colorado’s cool temperatures. It can be planted in both spring and fall, making it an excellent choice for those looking to maximize their garden space between slower-growing crops. This guide will walk you through the best practices for growing kohlrabi, tailored specifically for Colorado gardeners.
Planting Schedule by USDA Zone in Colorado
| Zone | Indoor start | Transplant out | Direct sow | Harvest |
|---|---|---|---|---|
| Zone 5b | Start March 1 – March 15, ~6–8 weeks before May 5 | Transplant outdoors May 10 – June 1, after the last frost | Direct sow outdoors May 10 – June 1, ensuring soil is warm | Harvest July 1 – September 1, when bulbs reach 3 inches in diameter |
| Zone 5a | Start March 10 – March 24, ~6–8 weeks before May 17 | Transplant outdoors May 20 – June 5, after the last frost | Direct sow outdoors May 20 – June 5, as soil warms | Harvest July 15 – September 10, when bulbs are optimal at 3 inches |
| Zone 6a | Start March 1 – March 15, ~6–8 weeks before April 25 | Transplant outdoors May 1 – May 10, after the last frost | Direct sow outdoors May 1 – May 10, to catch the growing season | Harvest June 15 – August 15, targeting 3-inch bulbs for best flavor |
Kohlrabi Planting Windows in Colorado
- Indoor start: Start your kohlrabi seeds indoors from March 1 to March 24, depending on your specific zone.
- Transplant outdoors: Transplant your kohlrabi seedlings outdoors from May 1 to June 5, ensuring it's after the last frost.
- Harvest: Aim to harvest your kohlrabi from June 15 through September 10, when bulbs reach about 3 inches in diameter.
Common Mistakes Growing Kohlrabi in Colorado
- Many Colorado gardeners underestimate the impact of late spring snow in higher elevations, which can damage tender kohlrabi seedlings. Protect them with row covers until the danger of frost passes.
- Some growers in Colorado mistakenly believe they can start kohlrabi too late in the spring without affecting yield. This can lead to tough, fibrous bulbs instead of the ideal tender ones, especially if the heat rises quickly.
- Overwatering is a common issue for Colorado gardeners due to the dry climate. Kohlrabi prefers consistent moisture but can suffer if the root zone is waterlogged. Ensure well-draining soil to avoid this pitfall.
- Ignoring soil temperatures can lead to poor seed germination when direct sowing kohlrabi. Plant in adequately warmed soil around May 10 to ensure growth as the chill of spring lingers into summer.
- Many don't utilize kohlrabi's greens in Colorado, viewing them as waste. However, these nutritious leaves can enhance dishes like stir-fries and soups, adding flavor and value.
Frequently Asked Questions
What if I'm in a cold pocket of Colorado?
If you're in a colder area, consider starting kohlrabi seeds indoors a bit earlier to give them a head start. Use row covers when transplanting outdoors to insulate against unexpected frosts.
Can I still plant kohlrabi in May?
Yes, in most Colorado zones, including 5b and 5a, May is an appropriate time to transplant kohlrabi outdoors, as long as the last frost date has passed. If you're in Zone 6a, you can start even earlier.
How do I know when to harvest my kohlrabi?
Kohlrabi is best harvested when the bulbs are around 3 inches in diameter. You can look for firmness and a smooth surface. If they're larger than 4 inches, they may become tough and woody.
What's the best way to prepare kohlrabi?
Kohlrabi can be enjoyed in various ways, but for raw eating, simply peel the tough skin, then slice or julienne for slaws. It's also excellent roasted or sautéed, bringing out a sweeter flavor.
Can I replant kohlrabi after harvesting?
Yes, kohlrabi can be replanted after harvesting the bulbs, making it an efficient crop for active gardening spaces. Be sure to time it for cooler weather to ensure optimal growth rate.
Keep Learning
City guides in Colorado
Other crops in Colorado
Typical fall sowing window for Kohlrabi in Colorado: July 21 – August 11.