Michigan gardeners should aim for a May planting of kohlrabi, taking advantage of the state’s moderate spring temperatures. Knowing the best time to plant kohlrabi in michigan is key to getting a crisp, sweet harvest before the summer heat turns it woody. This guide will walk you through every step, from soil prep to fall planting, so you can enjoy this unique vegetable all season long.
Kohlrabi is a cool-season crop that thrives in Michigan’s spring and fall weather. It looks like a alien spaceship but tastes like a mild, sweet turnip or broccoli stem. You can eat it raw, roasted, or in slaws.
Let’s get into the details so you don’t miss your window.
Understanding Michigan’s Growing Zones
Michigan spans USDA hardiness zones 4a in the Upper Peninsula to 6b in the southern Lower Peninsula. This affects your planting calendar. The best time to plant kohlrabi in michigan varies by a few weeks depending on where you live.
Zone 4 And 5 Northern Michigan
If you’re in the Upper Peninsula or northern Lower Peninsula, your last frost date is usually late May to early June. You have a shorter spring window. Plant kohlrabi seeds directly in the garden around mid-May, after the soil warms to at least 45°F.
Zone 6 Southern Michigan
Southern Michigan gardeners near Detroit, Ann Arbor, or Kalamazoo enjoy an earlier spring. Your last frost date is typically mid-April to early May. You can start seeds indoors in late March or direct sow in early April for a spring crop.
Best Time To Plant Kohlrabi In Michigan
The exact best time to plant kohlrabi in michigan is a two-part answer: early spring for a summer harvest, and late summer for a fall harvest. Spring planting gives you kohlrabi in June and July. Fall planting yields a sweeter, more tender crop in October.
Spring Planting Window
For spring, aim to plant kohlrabi seeds 2 to 4 weeks before your last expected frost date. Kohlrabi can tolerate light frosts, so don’t wait too long. In southern Michigan, that means planting in early to mid-April. In northern areas, target late April to early May.
Soil temperature is crucial. Kohlrabi seeds germinate best when the soil is between 45°F and 85°F. If the soil is too cold, seeds rot. Use a soil thermometer to check. If it’s below 45°F, wait a week.
Fall Planting Window
Fall planting is often more successful because the weather cools down as the kohlrabi matures. Plant seeds 8 to 10 weeks before your first expected fall frost. In southern Michigan, that’s around mid-July to early August. In northern areas, aim for late June to mid-July.
Fall kohlrabi tastes sweeter because cold temperatures convert starches to sugars. It also stores better in the ground under mulch.
How To Plant Kohlrabi In Michigan Soil
Kohlrabi is easy to grow if you follow a few steps. Michigan soil can be heavy clay or sandy loam. Amend it with compost for best results.
Soil Preparation
Kohlrabi prefers well-draining soil with a pH between 6.0 and 7.5. Test your soil with a home kit. If it’s too acidic, add lime in the fall before planting.
- Remove rocks and weeds from the bed.
- Mix in 2 to 3 inches of aged compost.
- Rake the soil smooth.
Direct Seeding Vs Transplants
You can start kohlrabi indoors or direct sow. Direct seeding is simpler and avoids transplant shock. Sow seeds ¼ to ½ inch deep, 1 inch apart in rows 12 to 18 inches apart. Thin seedlings to 4 to 6 inches apart once they have two true leaves.
If you use transplants, harden them off for a week before planting. Set them at the same depth they were in the pot. Water well after transplanting.
Watering And Mulching
Kohlrabi needs consistent moisture to stay tender. Water deeply once a week, or more often in dry spells. Mulch with straw or grass clippings to keep the soil cool and moist. This also prevents weeds.
Inconsistent watering causes the bulbs to crack or become tough. Use a soaker hose for even moisture.
Best Varieties For Michigan
Not all kohlrabi varieties perform the same in Michigan’s climate. Choose ones that mature quickly and resist bolting in heat.
Early Maturing Varieties
For spring planting, pick varieties that mature in 45 to 55 days. ‘Early White Vienna’ is a classic. It produces tender, pale green bulbs. ‘Early Purple Vienna’ is similar but with purple skin and white flesh.
Fall And Storage Varieties
For fall, try ‘Kossak’ or ‘Superschmelz’. These giant varieties take 60 to 70 days but store well. ‘Kossak’ can grow up to 10 inches wide without getting woody. ‘Superschmelz’ is known for its sweet flavor.
Common Mistakes Michigan Gardeners Make
Even experienced growers make errors with kohlrabi. Avoid these pitfalls.
Planting Too Late In Spring
If you plant kohlrabi in June, the heat will cause it to bolt (flower) and become woody. The bulb will taste bitter. Stick to the early spring window.
Overcrowding
Kohlrabi needs space to form bulbs. If you don’t thin seedlings, you’ll get tiny, misshapen bulbs. Thin to 4 to 6 inches apart for standard varieties, 8 to 12 inches for giant types.
Neglecting Pests
Flea beetles and cabbage worms love kohlrabi. Use row covers to protect young plants. Check for holes in leaves. Apply neem oil or insecticidal soap if needed.
Harvesting And Storing Kohlrabi
Kohlrabi is ready to harvest when the bulb is 2 to 3 inches in diameter for standard varieties, or up to 5 inches for giants. Don’t let it get too large or it becomes woody.
How To Harvest
Cut the stem at soil level with a sharp knife. Remove the leaves, leaving an inch of stem attached. The leaves are edible too—use them like kale or collards.
Storage Tips
Store unwashed kohlrabi in a plastic bag in the refrigerator. It keeps for 2 to 3 weeks. For longer storage, remove leaves and store bulbs in a root cellar at 32°F with high humidity.
Frequently Asked Questions
Can I Plant Kohlrabi In August In Michigan?
Yes, if you live in southern Michigan. Plant by early August for a fall harvest before the first frost. In northern Michigan, plant by mid-July.
What Is The Best Month To Plant Kohlrabi In Michigan?
April for spring planting in the south, May for the north. For fall, July to August depending on your zone.
Does Kohlrabi Need Full Sun?
Yes, it needs at least 6 hours of direct sun daily. Partial shade can work but may slow growth.
How Do I Know When Kohlrabi Is Ready To Pick?
When the bulb is 2 to 3 inches across and feels firm. Check the variety’s days to maturity on the seed packet.
Can Kohlrabi Survive A Frost?
Yes, it tolerates light frosts. In fact, frost improves sweetness. Cover plants if a hard freeze is forecast.
Final Tips For Michigan Growers
Kohlrabi is one of the easiest crops to grow in Michigan if you time it right. Start with spring planting in April or May, then follow up with a fall crop in July or August. Keep the soil moist and watch for pests.
You can also succession plant every 2 weeks for a continuous harvest. Just avoid planting during the hottest part of summer. The bulbs will thank you with crisp, sweet flavor.
Remember, the best time to plant kohlrabi in michigan is not a single date—it’s a window that opens in spring and closes in late summer. Pay attention to your local frost dates and soil temperature. With a little planning, you’ll have plenty of kohlrabi for salads, stir-fries, and snacks.
Happy growing, Michigan gardeners. Your kohlrabi patch awaits.