When to Plant Kohlrabi in Arizona (2026 Guide)
Kohlrabi, with its unique bulb-like stem that sits just above the soil surface, is a wonderful addition to your Arizona garden. This vegetable is not only easy to grow but also thrives under conditions similar to other brassicas like broccoli and cabbage. In Arizona, kohlrabi can be planted early in spring or later in the year, making it a versatile option for extending your harvests.
For the best results, timing your planting around frost dates is crucial. In the warmer zones such as Zone 8b, the last spring frost usually occurs on February 8, allowing you to start sowing seeds in early February. In contrast, cooler areas like Prescott, falling into Zone 5b, have a much later last frost date of May 4, which means planning your planting schedule carefully can lead to a fruitful kohlrabi harvest.
Whether you prefer the milder taste of green kohlrabi or the sweeter crunch of purple varieties, understanding when to plant will help ensure your success. This guide provides tailored information for growing kohlrabi in different Arizona hardiness zones to help you navigate local growing conditions effectively.
Planting Schedule by USDA Zone in Arizona
| Zone | Indoor start | Transplant out | Direct sow | Harvest |
|---|---|---|---|---|
| Zone 8b–9a | Start seeds indoors from December 10 – December 25, ~6–8 weeks before the last frost on February 8. | Transplant outdoors from February 20 – March 10, after the last frost. | Direct sow from February 20 – March 10, once the soil is workable. | Harvest from April 6 – June 6, when bulbs reach 3 inches in diameter. |
| Zone 7b–8a | Start seeds indoors from December 30 – January 15, ~6–8 weeks before the last frost on February 16. | Transplant outdoors from March 1 – March 20, after the last frost. | Direct sow from March 1 – March 20, once the soil is working. | Harvest from April 15 – June 15, when bulbs reach the desired size. |
| Zone 5b | Start seeds indoors from March 1 – March 15, ~6–8 weeks before the last frost on May 4. | Transplant outdoors from May 15 – May 20, after the last frost. | Direct sow from May 15 – May 20, once frost is fully past. | Harvest from June 1 – July 21, when bulbs are at their sweetest. |
Kohlrabi Planting Windows in Arizona
- Indoor start: In the warmer zones, start kohlrabi seeds indoors between December 10 and January 15 to provide ample time for growth before outdoor planting.
- Transplant outdoors: For outdoor transplanting, aim for February 20 to March 10 in warmer locations to ensure ideal cool-season conditions.
- Harvest: Expect to harvest kohlrabi from April 6 to July 21, depending on when you direct sow or transplant.
Common Mistakes Growing Kohlrabi in Arizona
- One common mistake among Arizona gardeners is not considering the extreme temperatures that can arise in late spring. Kohlrabi does best in cooler conditions, so planting too late can lead to bolting.
- Many novices underestimate the importance of proper soil drainage. In typical Arizona soil types, like clay, water can pool, which may lead to root problems and affect kohlrabi's growth.
- Gardening in Arizona also presents challenges with unpredictable late frosts in the higher zones. Ignoring the frost dates can result in failed crops when young plants experience frost damage.
- Another frequent issue is neglecting kohlrabi’s need for nutrients. Given Arizona's alkaline soil, regular soil amendments are essential to ensure healthy growth and bulb development.
- Finally, Arizona's harsh sun can give rise to heat stress if proper shading is not provided later in the season. Always consider using companion planting techniques to provide partial shade to younger kohlrabi plants.
Frequently Asked Questions
Can I still plant kohlrabi in May in Arizona?
It's generally not advisable to plant kohlrabi in May in most Arizona zones due to the rising heat, which can stress the plants and lead to bolting. Ideally, this should be planted earlier in the spring.
What if I'm in a cold pocket of Arizona?
If you find yourself in a colder area, be mindful of the last frost date before planting. Consider starting kohlrabi indoors to allow for a head start and transplant only when the danger of frost has passed.
How do I improve my soil for growing kohlrabi?
To enhance soil quality for kohlrabi, add compost or well-rotted manure to improve nutrient levels and drainage. This is essential in Arizona's often alkaline soil, which can hinder plant growth if not properly managed.
Is there a specific variety of kohlrabi better for Arizona?
Yes, choose purple kohlrabi varieties, which tend to be more heat-tolerant and can withstand warmer planting conditions without compromising on flavor.
What pests should I watch for with kohlrabi in Arizona?
Common pests include aphids, flea beetles, and cabbage worms. Regular monitoring and appropriate organic pest control measures will help keep these pests under control without impacting your garden's health.
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Other crops in Arizona
Typical fall sowing window for Kohlrabi in Arizona: September 23 – October 14.