When to Plant Kohlrabi in California (2026 Guide)

Kohlrabi is an increasingly popular vegetable choice in California gardens, praised for its unique flavor and ease of growth. With its distinct bulbous stem and crisp texture, this versatile brassica can elevate a variety of dishes, from salads to stir-fries. Understanding the best times to plant kohlrabi is crucial as it flourishes in cooler weather, making early spring and late summer ideal for planting.

In California, the frost dates vary significantly across different zones. For instance, in Zone 9b, the median last spring frost is as early as January 11, while Zone 7b–8a typically sees its last frost around February 26. Knowing these dates can help gardeners maximize their kohlrabi harvests before the heat sets in, ensuring optimal growth and development.

Each zone has its unique characteristics that dictate the timing of planting, transplanting, and harvesting kohlrabi. For those in warmer regions, like Alhambra, the planting window may be more restricted, while those in cooler zones, like Aptos, have a longer frost-free season to cultivate this delicious vegetable. Planning accordingly can lead to a bountiful yield.

Planting Schedule by USDA Zone in California

Zone	Indoor start	Transplant out	Direct sow	Harvest
Zone 8b–9a	Start January 1 – January 15, ~6 weeks before the last frost on January 31	Transplant outdoors from February 1 – February 15 after the last frost	Direct sow from March 1 – May 15, after the danger of frost	Harvest from April 15 – June 15, about 45–60 days after transplant
Zone 7b–8a	Start January 1 – January 15, ~6 weeks before the last frost on February 26	Transplant outdoors from March 1 – March 15 after the last frost	Direct sow from March 15 – June 1, once frost danger has passed	Harvest from May 15 – July 15, about 45–60 days after transplant
Zone 9b	Start January 1 – January 5, ~6 weeks before the last frost on January 11	Transplant outdoors from January 10 – January 15 after the last frost	Direct sow from January 10 – January 30, as the frost-free season is brief	Harvest from January 30 – March 15, about 45–60 days after transplant

Kohlrabi Planting Windows in California

Indoor start: For optimal growth, start kohlrabi indoors between January 1 and January 15.
Transplant outdoors: Transplant your kohlrabi outside from February 1 to February 15 for the California climate.
Harvest: The harvest window for kohlrabi is from April 15 to June 15, depending on when it was planted.

Common Mistakes Growing Kohlrabi in California

Many gardeners in California underestimate the impact of late spring frosts, particularly in coastal areas. This can be detrimental for kohlrabi seeds or transplants if proper timing is not observed.
A common mistake is planting kohlrabi too late in Zone 7b–8a. By delaying planting past mid-June, gardeners may find their crops struggling with excessively warm weather, leading to tough and fibrous bulbs.
California's unique climate demands awareness of microclimates. A garden that appears to have a milder climate may still experience unexpected temperature fluctuations, impacting kohlrabi growth.
Using heavy or poorly-draining soil can hinder kohlrabi development in California's varied weather. Ensure the soil is well-draining to prevent rot and disease, especially during wet periods.
One often overlooked factor is proper spacing between kohlrabi plants. Crowding them can reduce air circulation and increase the risk of disease, particularly in California's humid coastal areas.

Frequently Asked Questions

When should I start kohlrabi indoors in California?

You should start kohlrabi indoors in California between January 1 and January 15. This timing ensures that your seedlings will be ready for transplanting once the frost danger has passed.

Can I still plant kohlrabi in May?

In California, it's generally not recommended to plant kohlrabi in May, especially in cooler zones, as the temperatures rise and may hinder proper growth. It's best to follow the suggested planting windows.

What happens if I miss the outdoor transplant window?

If you miss the outdoor transplant window for kohlrabi, you may need to adjust your planting schedule and consider planting a heat-tolerant variety. Otherwise, your plants might not thrive in warmer conditions.

How much space should I give each kohlrabi plant?

Each kohlrabi plant should have at least 6 to 8 inches of space around it to promote airflow and reduce competition for nutrients. Proper spacing helps improve overall plant health.

Is kohlrabi frost tolerant?

Yes, kohlrabi is frost tolerant, making it a great option for early spring and fall planting in California. Just be cautious about late spring frosts, especially in cooler coastal areas.

Keep Learning

Typical fall sowing window for Kohlrabi in California: September 22 – October 13.