When to Plant Kohlrabi in Vermont (2026 Guide)

If you're looking to grow kohlrabi in Vermont, timing is crucial for a successful harvest. With the median last spring frost occurring on May 8, getting your plants in the ground at the right moment is vital. This quirky brassica can thrive in the available frost-free days, which span approximately 148 days each year.

Kohlrabi, known for its unique appearance and mild flavor, is a highly versatile vegetable that can be harvested as early as 45 days after transplanting. Whether you're a seasoned gardener or a newbie in Vermont, understanding when to sow your seeds will pave the way for a bountiful harvest. The stunning purple and pale green varieties offer value to your garden plot both visually and nutritionally.

Keep in mind that the first fall frost typically arrives by October 3, providing a window for late summer plantings. These conditions mean that kohlrabi can be planted once or twice each growing season, allowing for a staggered harvest to ensure fresh produce from late spring to early fall. Ready to learn how to perfectly time your kohlrabi crop to take advantage of Vermont's growing season?

Planting Schedule by USDA Zone in Vermont

Zone	Indoor start	Transplant out	Direct sow	Harvest
Zone 5b	Start March 15 – March 29, ~6–8 weeks before May 8	Transplant outdoors April 15 – May 1, after May 8 frost date	Direct sow April 15 – May 1, after May 8 frost date	Harvest from June 15 – August 1, ideally when bulbs reach 3 inches

Kohlrabi Planting Windows in Vermont

Indoor start: Begin your indoor kohlrabi seed starting between March 15 and March 29.
Transplant outdoors: Transplant your kohlrabi outdoors between April 15 and May 1.
Harvest: You can expect to harvest your kohlrabi from June 15 to August 1.

Common Mistakes Growing Kohlrabi in Vermont

One common mistake among Vermont gardeners is rushing to plant kohlrabi too early, risking frost damage. Remember that the last spring frost in Zone 5b is May 8, which signals the proper time for outdoor planting. Check forecasts closely in April and avoid early sowing to secure healthy plants.
Another common error is not considering soil preparation. The clay soil often found in parts of Vermont can hinder kohlrabi growth if not properly amended. Ensure you enrich your soil with organic matter to improve drainage and nutrient profiles before planting kohlrabi.
Some gardeners overlook the importance of regular watering. Kohlrabi thrives in consistent moisture, but in the humid environment of Vermont, allowing the soil to dry too much can lead to tough, fibrous stems. Water your plants consistently, especially during dry spells.
Believe it or not, waiting too long to harvest is a mistake as well. In Vermont, allowing kohlrabi bulbs to reach over 4 inches can result in a woody texture. Monitor your plants closely, and aim to harvest them at 3 inches for optimal flavor and tenderness.
Finally, many Vermont gardeners fail to rotate their kohlrabi crop with other brassicas in subsequent seasons. Rotating can help break disease cycles and improve soil health. Always consider a 3-year rotation phase with your kale, cabbage, and other brassica plants.

Frequently Asked Questions

What if I'm in a cold pocket of Vermont?

If you're in a colder region of Vermont, opt for a slightly later transplant date. Monitor local frost dates, and start your seeds indoors if necessary to give them a head start before moving them outside.

Can I still plant kohlrabi in May?

Yes, you can plant kohlrabi in May, but it’s advisable to do so early in the month, ideally within the first two weeks. This way, you can ensure your crops have enough time to mature before the fall frosts set in.

What if my kohlrabi develops tough stems?

If your kohlrabi stems become tough, you likely harvested them too late. Harvest regularly as they reach about 3 inches in diameter to avoid this issue and to enjoy their mild flavor and crisp texture at their best.

How can I improve my soil for kohlrabi?

Improve your soil by incorporating organic matter like compost or aged manure. This will enhance soil structure, drainage, and nutrient availability, all crucial for robust kohlrabi growth in Vermont's conditions.

Are there specific kohlrabi diseases I should watch for?

Yes, be on the lookout for diseases like downy mildew and clubroot. Both can affect kohlrabi. Maintaining proper air circulation and crop rotation can significantly reduce the incidence of these diseases.