When to Plant Kohlrabi in Alaska (2026 Guide)

Kohlrabi is a unique and engaging vegetable choice for Alaskan gardeners, known for its bulb-like swollen stem that grows just above the soil. With its sweet, mild flavor resembling that of broccoli stems, kohlrabi is not only easy to grow but also versatile and delicious in various dishes. In Alaska, optimal planting is crucial due to specific frost dates, particularly the median last spring frost on May 26 and the median first fall frost on September 10, defining the gardening calendar.

As we focus on growing kohlrabi in Alaska, it is essential to understand the local growing conditions and the unique climate challenges we face. With a frost-free season of approximately 107 days in Zone 5a encompassing cities like Anchorage, gardeners can take advantage of this window to plant and harvest kohlrabi effectively. This cool-loving crop thrives in our conditions, making it a fantastic addition to your garden plans, whether intercropped or planted in the traditional way.

In the following sections, we will break down specific planting strategies and timelines, as well as address common misconceptions and mistakes that can hinder your kohlrabi success. Emphasizing correct planting windows and care techniques will help ensure a bountiful harvest in your Alaskan garden. Let's dive into the specifics of when and how to plant kohlrabi in the Last Frontier to enjoy this flavorful brassica.

Planting Schedule by USDA Zone in Alaska

Zone	Indoor start	Transplant out	Direct sow	Harvest
Zone 5a	Start seeds indoors from April 10 – April 24, ~4–6 weeks before transplanting outdoors.	Transplant outdoors from May 26 – June 10, after the last frost date.	Direct sow seeds from June 1 – June 15 for a fall crop, taking advantage of the cool weather.	Harvest kohlrabi from July 10 – August 15 when bulbs are about 3 inches in diameter.

Kohlrabi Planting Windows in Alaska

Indoor start: Start your kohlrabi seeds indoors from April 10 to April 24 for the best results.
Transplant outdoors: Transplant your kohlrabi seedlings outdoors between May 26 and June 10.
Harvest: You can expect to harvest your kohlrabi from July 10 to August 15, when the bulbs reach the ideal size.

Common Mistakes Growing Kohlrabi in Alaska

One common mistake is planting kohlrabi too late in Alaska's growing season. By waiting too long, you risk the first fall frost occurring before bulbs have enough time to mature. Timely planning, especially around the median last frost date of May 26, is essential.
Overcrowding plants is another mistake many Alaska gardeners make when planting kohlrabi. Since kohlrabi needs space to bulb properly, ensure you follow recommended spacing. Crowded plants can compete for nutrients and moisture, resulting in smaller and less flavorful bulbs.
Neglecting the unique characteristics of Alaska's climate can lead to issues with kohlrabi growth. Late spring snowfalls or sudden temperature drops can occur, affecting young seedlings. Monitor local weather patterns closely to safeguard against unexpected frosts.
Using improper soil conditions is a big mistake for growing kohlrabi in Alaska. Many Alaskan soils are too alkaline or poorly drained for optimal growth. Conducting a soil test before planting can help ensure your soil has the right pH and nutritional balance.
Another oversight is underestimating the benefits of companion planting in Alaska's gardening ecosystem. Failing to plant kohlrabi alongside slower-growing crops can miss out on maximizing your garden's productivity. The compact growth habit of kohlrabi allows for efficient interplanting in available spaces.

Frequently Asked Questions

Can I grow kohlrabi in a colder pocket of Alaska?

Yes, kohlrabi can still be grown in colder areas of Alaska, but it's crucial to time your plantings according to local frost dates. Use season extension methods, like row covers, to help protect young plants from unexpected frosts.

What if I missed the planting window in May?

If you missed the May transplant window, you can still directly sow kohlrabi seeds outdoors until mid-June. This gives you a chance for a fall crop, just make sure to monitor mature bulbs before the first fall frost.

How deep should I plant kohlrabi seeds?

Kohlrabi seeds should be planted about half an inch deep in well-prepared soil. Ensure good soil contact for germination and watch for moisture, especially in early seedling stages.

Can kohlrabi survive a light frost?

Yes, kohlrabi is frost-tolerant and can withstand light frosts. This makes it suitable for early spring planting in Alaska, but be cautious about strong freezes that could damage the plants.

What other crops grow well with kohlrabi?

Kohlrabi works well with fast-growing crops like radishes or slower growers like tomatoes and peppers. Utilized wisely, kohlrabi can fill in gaps and maximize harvests in your garden throughout the season.