When to Plant Kohlrabi in Illinois (2026 Guide)
Kohlrabi is a delightful and versatile vegetable that can thrive in the rich soils of Illinois. With a crisp, juicy texture and a mild flavor reminiscent of broccoli, this unique brassica is perfect for both raw and cooked dishes. As the last spring frost in many areas like Aurora is around April 26, understanding the planting timeline for kohlrabi is critical for success.
In Illinois, kohlrabi can be planted in both spring and fall to maximize your gardening season. Notably, the earlier you plant, the better your chances of avoiding heat stress, as kohlrabi prefers cooler temperatures. The first fall frost in zones such as Rockford typically occurs around October 8, providing a robust time frame for your fall plantings.
This guide provides detailed planting schedules, including optimal times for indoor starts, outdoor transplants, and when to expect your harvest. Whether you are a seasoned gardener or a beginner eager to explore this unusual vegetable, you'll find valuable information tailored to Illinois's unique climate and frost patterns.
Planting Schedule by USDA Zone in Illinois
| Zone | Indoor start | Transplant out | Direct sow | Harvest |
|---|---|---|---|---|
| Zone 6a | Start February 15 – March 1, ~6–8 weeks before April 26 | Transplant outdoors May 3 – May 10, after the last frost | Direct sow seeds April 27 – May 10 | Harvest from June 17 – July 1, 45–60 days after sowing |
| Zone 6b | Start February 1 – February 15, ~6–8 weeks before April 13 | Transplant outdoors April 28 – May 5, after the last frost | Direct sow seeds April 14 – May 5 | Harvest from June 30 – July 14, 45–60 days after sowing |
| Zone 5b | Start March 1 – March 15, ~6–8 weeks before May 3 | Transplant outdoors May 4 – May 10, after the last frost | Direct sow seeds May 4 – May 15 | Harvest from June 27 – July 11, 45–60 days after sowing |
Kohlrabi Planting Windows in Illinois
- Indoor start: Start your kohlrabi seeds indoors from February 1 to March 15, depending on your zone.
- Transplant outdoors: Transplant kohlrabi outdoors between April 28 and May 10 for the best results.
- Harvest: Expect to harvest your kohlrabi from late June through mid-July, depending on when you planted it.
Common Mistakes Growing Kohlrabi in Illinois
- One common mistake Illinois gardeners make is planting kohlrabi too late in the season. If you wait too long and encounter warmer weather, the bulbs may become woody. Aim for early spring planting to avoid heat stress.
- Many first-time gardeners in Illinois often underestimate the importance of soil moisture for kohlrabi. Ensuring even soil moisture helps kohlrabi thrive. Irregular watering can lead to undesirable textures and flavors.
- Neglecting to provide adequate spacing can result in overcrowding, which is common among new gardeners in Illinois. Ensure you space your kohlrabi plants adequately to promote airflow and healthy growth, typically around 12 inches apart.
- In Illinois, many believe kohlrabi is strictly a spring crop and miss the opportunity to plant in fall. However, with a correctly timed planting schedule, you can enjoy kohlrabi into the fall months, providing a fresh harvest later in the year.
- Gardeners often overlook the edible leaves of kohlrabi. While the bulb is the main focus, the leaves are nutritious and can be used in various dishes. Don’t waste these green treasures; incorporate them into your meals!
Frequently Asked Questions
What if I'm in a cold pocket of Illinois?
If you're gardening in a colder area, consider extending your indoor start time by a week or two. This can help kohlrabi mature properly before the colder weather sets in. Also, use protective coverings like row covers if frost threatens.
Can I still plant kohlrabi in May?
Yes, if you're in Zone 6a, you can still directly sow kohlrabi seeds until early May. Just be mindful of the potential for heat stress as summer approaches and plan to harvest on the earlier side.
How often should I water kohlrabi?
Kohlrabi prefers consistent moisture, so aim to water it at least once a week, depending on rainfall. However, if you experience drought conditions, consider watering more frequently to keep the soil evenly moist.
Why are my kohlrabi bulbs becoming tough?
Tough kohlrabi bulbs are often the result of heat stress or delayed harvesting. Ensure you’re planting early enough in the season, and aim to harvest them when they reach about 3 inches in diameter for the best texture.
Can kohlrabi be grown in containers?
Absolutely! Kohlrabi grows well in containers as long as the pot is deep enough to accommodate its bulbous form. Look for containers that are at least 12 inches deep to give kohlrabi ample growing space.
Keep Learning
City guides in Illinois
Other crops in Illinois
Typical fall sowing window for Kohlrabi in Illinois: August 1 – August 22.