Table of Contents
Growing kohlrabi in a cold frame is an excellent way to enjoy fresh, crisp vegetables early in the spring. Cold frames provide a protected environment that helps extend the growing season, allowing you to start your kohlrabi earlier than outdoor planting would normally permit.
Choosing the Right Time and Location
Select a sunny spot for your cold frame, ideally one that receives at least 6 hours of direct sunlight daily. The best time to start planting kohlrabi is 4 to 6 weeks before the last expected frost date in your area. This ensures the plants have a warm environment to grow without the risk of frost damage.
Preparing the Cold Frame and Soil
Ensure your cold frame is clean and well-ventilated. Fill it with rich, well-draining soil enriched with compost. Kohlrabi prefers loose, fertile soil with a pH between 6.0 and 7.5. Mix compost into the soil to provide essential nutrients for healthy growth.
Seed Selection and Sowing
Choose fast-maturing kohlrabi varieties suitable for early planting. Sow seeds about ½ inch deep, spacing them 2 inches apart in rows 12 inches apart. Cover lightly with soil and water gently to keep the soil moist.
Caring for Your Kohlrabi
Keep the soil consistently moist but not waterlogged. Ventilate the cold frame on warm days to prevent overheating and maintain a temperature of around 45-75°F. Thin seedlings to 4 inches apart once they develop their first true leaves, ensuring enough space for bulb development.
Fertilizing and Maintenance
Apply a balanced fertilizer every few weeks to promote healthy growth. Regularly check for pests such as aphids or cabbage worms, and remove any affected leaves. Mulching around the plants can help retain moisture and suppress weeds.
Harvesting Your Kohlrabi
Most kohlrabi varieties are ready to harvest 45 to 60 days after planting. The bulbs should be 2 to 4 inches in diameter. Harvest by cutting the bulb at the base with a sharp knife. Early harvesting ensures tender, sweet kohlrabi perfect for salads or cooking.
Tips for Success
- Start seeds indoors if your spring is very cold.
- Maintain consistent moisture levels for best bulb development.
- Rotate crops yearly to prevent soil-borne diseases.
- Use row covers to protect young plants from pests and frost.