When to Plant Kohlrabi in Washington (2026 Guide)
Kohlrabi, an intriguing member of the brassica family, is gaining popularity among gardeners in Washington for its unique flavor and versatility. This vegetable, known for its swollen stem that resembles a bulb, can be enjoyed raw or cooked. With ideal growing conditions, kohlrabi can thrive throughout the state's diverse climates, especially with the proper timing of planting around key frost dates like April 9 and October 26.
For Washington gardeners, understanding when to plant kohlrabi is crucial to harvest beautiful, crisp bulbs. Whether you reside in urban cities like Seattle or Spokane, or more rural areas, timing your planting and using the right techniques will lead to success. Kohlrabi benefits from the cooler temperatures of early spring and fall, and by following this guide, you can ensure a bountiful crop.
In Washington, kohlrabi can be a great addition to your vegetable garden. It is especially favored for its fast-growing nature, maturing within 45–60 days from transplanting. With meticulous attention to your local frost dates, you can avoid the pitfalls of late frosts that could affect your harvest and enjoy the stunning flavor of freshly grown kohlrabi.
Planting Schedule by USDA Zone in Washington
| Zone | Indoor start | Transplant out | Direct sow | Harvest |
|---|---|---|---|---|
| Zone 6b | Start February 15 – March 1, ~6–8 weeks before April 9 | Transplant outdoors between April 10 – April 20, after the last frost | Direct sow seeds April 10 – May 1, after the last frost | Harvest from June 1 – June 30, when bulbs reach 3 inches in diameter |
| Zone 6a | Start February 20 – March 5, ~6–8 weeks before April 20 | Transplant outdoors between April 21 – May 1, after the last frost | Direct sow seeds April 20 – May 10, after the last frost | Harvest from June 15 – July 15, when bulbs reach 3 inches in diameter |
| Zone 5b | Start March 1 – March 15, ~6–8 weeks before May 6 | Transplant outdoors between May 7 – May 15, after the last frost | Direct sow seeds May 6 – May 20, after the last frost | Harvest from June 30 – July 30, when bulbs reach 3 inches in diameter |
Kohlrabi Planting Windows in Washington
- Indoor start: In Washington, indoor sowing should occur between February 15 and March 15 depending on your hardiness zone.
- Transplant outdoors: Outdoor transplanting for kohlrabi typically occurs between April 10 and May 15 based on frost dates in your area.
- Harvest: Kohlrabi should be harvested from June 1 through July 30, allowing for the best flavor and texture of the bulbs.
Common Mistakes Growing Kohlrabi in Washington
- One common mistake among Washington gardeners is rushing to transplant kohlrabi too early. In regions like Spokane, it's vital to ensure the risk of frost on April 9 has passed before moving your plants outdoors.
- Many gardeners fail to account for Washington's sporadic late spring snows, which can damage young kohlrabi plants. Monitoring the local weather is essential to protect your crop during unpredictable weather patterns.
- Not taking advantage of kohlrabi's frost tolerance can lead to missed harvests. Washington growers should consider harvesting kohlrabi before potential fall frosts, particularly in urban areas like Seattle, where temperatures can drop quickly.
- Another mistake is neglecting soil conditions and drainage. Washington's clay soils can retain moisture, leading to rotting. Incorporating organic matter can improve drainage and support healthier kohlrabi growth.
- Many think kohlrabi will thrive in full sun, but Washington's coastal fog can weaken plants. Position your crops to ensure they receive enough sunlight while protecting them from excessive dampness.
Frequently Asked Questions
When should I plant kohlrabi in Washington?
The optimal planting window for kohlrabi in Washington varies by zone. Generally, you can start sowing seeds indoors by mid-February and transplant them outdoors by mid-April to late May, depending on your specific region.
Can I still plant kohlrabi in May?
Yes, you can still plant kohlrabi in May, especially in areas like Zone 5b, where the last frost date is around May 6. However, be sure to choose quick-maturing varieties to ensure a successful harvest.
What if I'm in a cold pocket of Washington?
If you find yourself in a colder area, consider starting your kohlrabi seeds indoors earlier and using protective covers when transplanting outdoors. Pay close attention to local frost dates to time your plantings effectively.
How can I tell when kohlrabi is ready to harvest?
Kohlrabi should be harvested when the bulbs reach about 3 inches in diameter. Larger bulbs can become woody and fibrous; it's best to check them regularly during the harvest window for optimal flavor.
Is it necessary to peel kohlrabi before eating?
Yes, it is advisable to peel kohlrabi because the skin can be tough and bitter. Once peeled, thinly slice or julienne it for salads or slaws to enjoy its mild, sweet flavor.
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City guides in Washington
Other crops in Washington
Typical fall sowing window for Kohlrabi in Washington: August 17 – September 7.