South Carolina’s warm soil in early spring welcomes kohlrabi seeds directly outdoors by mid-March. Finding the best time to plant kohlrabi in south carolina depends on your specific region and the season you want to harvest. This guide will walk you through the exact timing for spring and fall crops, soil prep, and care tips so you get crisp, sweet bulbs every time.
Understanding South Carolina’s Growing Zones For Kohlrabi
South Carolina spans USDA hardiness zones 7a in the upstate to 8b along the coast. This affects when you can plant. Kohlrabi is a cool-season crop that thrives in temperatures between 40°F and 75°F. It hates heat and will bolt or become woody if planted too late in spring.
In the Piedmont and upstate (zones 7a-7b), your spring window opens a bit later than in the Lowcountry. Coastal areas (zones 8a-8b) warm up faster, so you can start earlier. Fall planting is actually easier for most of the state because the weather cools down more reliably.
Spring Planting Windows By Region
For spring planting, you want to get kohlrabi in the ground 2-4 weeks before the last frost date. In South Carolina, the last frost ranges from late March in the Lowcountry to mid-April in the mountains.
- Lowcountry (Charleston, Hilton Head): Plant seeds outdoors from mid-February to mid-March
- Midlands (Columbia, Sumter): Plant seeds outdoors from early March to late March
- Upstate (Greenville, Spartanburg): Plant seeds outdoors from mid-March to early April
You can also start seeds indoors 4-6 weeks before transplanting. But direct sowing is simpler and works well because kohlrabi doesn’t like root disturbance.
Fall Planting Windows
Fall is the best time to grow kohlrabi in South Carolina. The weather is more stable, and the flavor gets sweeter after a light frost. Count back 8-10 weeks from your first fall frost date. First frost usually hits in early November for the upstate and mid-November for the coast.
- Lowcountry: Plant seeds from late August to mid-September
- Midlands: Plant seeds from mid-August to early September
- Upstate: Plant seeds from early August to late August
For a continuous harvest, plant a small batch every two weeks during these windows. This gives you fresh kohlrabi from October through December.
Best Time To Plant Kohlrabi In South Carolina
The exact best time to plant kohlrabi in south carolina is early spring for a summer harvest and late summer for a fall harvest. For spring, aim for soil temperatures around 50°F to 60°F. For fall, plant when soil temps are still warm but air temps are starting to drop.
Kohlrabi seeds germinate best when soil is consistently moist and between 45°F and 85°F. If you plant too early in cold, wet soil, seeds may rot. If you plant too late in hot weather, the plants will bolt quickly.
Here’s a simple rule: plant spring kohlrabi when daffodils are blooming in your area. Plant fall kohlrabi when the first hints of cooler nights appear in late August.
Soil Preparation For Kohlrabi
Kohlrabi grows best in well-drained, loamy soil with a pH between 6.0 and 7.5. Before planting, work in 2-3 inches of compost or well-rotted manure. This adds nutrients and improves moisture retention.
Add a balanced fertilizer like 10-10-10 at a rate of 1 pound per 100 square feet. Mix it into the top 6 inches of soil. Avoid too much nitrogen, which can cause lush leaves but small bulbs.
If your soil is heavy clay, consider raised beds. Kohlrabi bulbs can rot in waterlogged soil. Sandy soil works fine but needs more frequent watering and organic matter.
How To Plant Kohlrabi Seeds
Direct sowing is the easiest method. Here’s how:
- Prepare the soil as described above
- Sow seeds 1/4 to 1/2 inch deep
- Space seeds 1 inch apart in rows 12-18 inches apart
- Water gently after planting
- Thin seedlings to 4-6 inches apart when they have 2-3 true leaves
If you prefer transplants, start seeds indoors 4-6 weeks before your planting date. Use biodegradable pots to avoid root disturbance. Harden off seedlings for a week before transplanting.
Watering And Mulching
Kohlrabi needs consistent moisture to develop tender bulbs. Water deeply once or twice a week, providing about 1 inch of water per week. In sandy soil, you may need to water more often.
Mulch around plants with straw, shredded leaves, or grass clippings. This keeps soil cool, retains moisture, and suppresses weeds. Apply mulch after the soil has warmed up in spring, or immediately after planting in fall.
Irregular watering can cause the bulbs to crack or become tough. Use a soaker hose or drip irrigation for best results.
Fertilizing During The Growing Season
Kohlrabi is a moderate feeder. Side-dress with a balanced fertilizer when the plants are about 4 inches tall. Use about 1/2 cup of 10-10-10 per 10 feet of row. Water it in well.
You can also use a liquid fertilizer like fish emulsion every 2-3 weeks. Stop fertilizing once the bulbs start to swell, usually 4-6 weeks after planting.
Too much nitrogen will produce giant leaves but small, woody bulbs. Stick to the recommended amounts.
Common Pests And Diseases
Kohlrabi is a member of the cabbage family, so it shares the same pests. The most common are:
- Cabbage worms: Small green caterpillars that eat leaves. Use row covers or spray with Bt (Bacillus thuringiensis)
- Aphids: Tiny insects that suck sap. Wash off with water or use insecticidal soap
- Flea beetles: Small jumping beetles that make tiny holes in leaves. Use row covers or diatomaceous earth
- Clubroot: A soil-borne disease that causes swollen, distorted roots. Rotate crops and avoid planting in infected soil
Row covers are the best prevention. Install them right after planting and keep them on until the plants are established. This blocks most pests without chemicals.
Harvesting Kohlrabi At The Right Time
Kohlrabi is ready to harvest when the bulb is 2-3 inches in diameter. This usually takes 45-70 days from planting, depending on the variety. Don’t let them get bigger than 4 inches, or they become tough and woody.
To harvest, cut the stem just below the bulb with a sharp knife. Remove the leaves, but leave the root attached. The leaves are edible too—use them like collard greens or kale.
Spring-planted kohlrabi should be harvested before temperatures regularly exceed 80°F. Fall-planted kohlrabi can stay in the ground through light frosts, which sweeten the flavor.
Storing Fresh Kohlrabi
Kohlrabi stores well in the refrigerator for 2-3 weeks. Remove the leaves first, as they draw moisture from the bulb. Place the bulbs in a plastic bag in the crisper drawer.
For longer storage, you can keep kohlrabi in a root cellar or cold basement for 2-3 months. Wrap each bulb in newspaper and store them in a box with ventilation. Keep the temperature around 32°F to 40°F with high humidity.
You can also blanch and freeze kohlrabi. Peel and dice the bulbs, blanch for 2 minutes, then cool in ice water. Drain and pack in freezer bags. Frozen kohlrabi keeps for 8-12 months.
Best Kohlrabi Varieties For South Carolina
Choose varieties that mature quickly and handle heat well. Here are top picks:
- Early White Vienna: Matures in 50-55 days. Classic white bulb, tender and sweet. Great for spring planting
- Purple Vienna: Matures in 55-60 days. Purple skin, white flesh. More cold-tolerant than white varieties
- Korridor: Matures in 45-50 days. Very fast, ideal for fall planting. Resistant to bolting
- Kolibri: Matures in 50-55 days. Purple skin, uniform bulbs. Good for both spring and fall
- Superschmelz: Matures in 60-70 days. Giant bulbs up to 10 inches, but still tender. Best for fall planting
For spring, stick with fast-maturing varieties like Early White Vienna or Korridor. For fall, you can try larger types like Superschmelz.
Succession Planting For Continuous Harvest
To enjoy kohlrabi for weeks, plant every 2-3 weeks during your planting windows. For spring, make 2-3 plantings from mid-February to early April. For fall, plant every 2 weeks from August through September.
Keep a garden journal to track your planting dates and harvest times. This helps you refine your schedule each year based on your local weather patterns.
Remember that kohlrabi doesn’t like heat. If a heat wave hits, provide shade cloth or harvest early. Overmature kohlrabi is still edible but not as good.
Growing Kohlrabi In Containers
If you have limited space, kohlrabi grows well in containers. Use a pot at least 12 inches deep and wide. Fill with quality potting mix mixed with compost.
Plant seeds 1/4 inch deep and thin to 4-6 inches apart. Water more frequently because containers dry out faster. Fertilize with a liquid fertilizer every 2 weeks.
Place the container in full sun (6-8 hours daily). In hot weather, move it to partial shade to prevent bolting. Harvest when bulbs are 2-3 inches.
Companion Planting For Kohlrabi
Good companions help deter pests and improve growth. Plant kohlrabi near:
- Beets: They don’t compete for nutrients
- Onions and garlic: Their smell repels cabbage worms
- Mint: Deters aphids and flea beetles
- Nasturtiums: Trap aphids away from kohlrabi
Avoid planting near:
- Strawberries: They can stunt kohlrabi growth
- Tomatoes: They compete for nutrients and space
- Other brassicas (cabbage, broccoli, kale): They share pests and diseases
Troubleshooting Common Problems
If your kohlrabi bulbs are small or not forming, check these factors:
- Too much heat: Plant earlier in spring or later in fall
- Too much nitrogen: Use less fertilizer
- Overcrowding: Thin seedlings to proper spacing
- Inconsistent watering: Keep soil evenly moist
- Pest damage: Use row covers or organic sprays
If bulbs crack, it’s usually from uneven watering. Mulch helps prevent this. If leaves turn yellow, check for root rot from overwatering or poor drainage.
Extending The Growing Season
You can extend your kohlrabi harvest by using season extenders. In early spring, use row covers or cold frames to warm the soil and protect from late frosts. In fall, use the same covers to protect from early frosts.
Kohlrabi can tolerate light frosts down to 25°F. If a hard freeze is forecast, cover plants with blankets or bring containers indoors. Mulch heavily around the base to protect the roots.
With protection, you can harvest kohlrabi into December in most of South Carolina. In the Lowcountry, you might even get a winter crop if you plant in October.
Frequently Asked Questions
Can I plant kohlrabi in summer in South Carolina?
Summer is too hot for kohlrabi. It will bolt quickly and become woody. Stick to spring and fall planting. If you want a summer crop, choose a heat-tolerant variety and provide shade, but results are often poor.
How long does kohlrabi take to grow from seed?
Most varieties mature in 45-70 days from seeding. Fast varieties like Korridor are ready in 45-50 days. Slower giants like Superschmelz take 60-70 days. Check the seed packet for exact days to maturity.
Do I need to fertilize kohlrabi after planting?
Yes, but lightly. Side-dress with a balanced fertilizer when plants are 4 inches tall. Avoid high-nitrogen fertilizers. Too much nitrogen causes big leaves but small bulbs.
Can I grow kohlrabi in partial shade?
Kohlrabi needs full sun (6-8 hours) for best growth. In partial shade, it will grow slower and produce smaller bulbs. If you have no full-sun spot, choose a fast-maturing variety and expect smaller harvests.
Why are my kohlrabi bulbs tough and woody?
This usually happens from heat stress or waiting too long to harvest. Harvest bulbs when they are 2-3 inches wide. If a heat wave hits, harvest early even if bulbs are small. Also, ensure consistent watering.
Planting at the best time to plant kohlrabi in south carolina is the key to success. Stick to early spring and late summer windows, prepare your soil well, and harvest at the right size. With these tips, you’ll enjoy crisp, sweet kohlrabi from your garden for months.