Kohlrabi, a member of the cabbage family, is a unique and versatile vegetable that thrives in cooler climates. This fascinating plant is often overlooked by home gardeners but can be a rewarding crop to grow in Delaware’s temperate climate. In this article, we will explore the essential steps to successfully cultivate kohlrabi, including soil preparation, planting, maintenance, pest management, and harvesting.
Understanding Kohlrabi
Kohlrabi (Brassica oleracea var. gongylodes) is often referred to as the “turnip cabbage” because of its bulbous stem, which sits above the ground. It can be green or purple in color and has a crunchy texture with a mild, sweet flavor. Packed with nutrients such as vitamin C, potassium, and fiber, kohlrabi can be enjoyed raw in salads, roasted, or cooked in various dishes.
Ideal Growing Conditions
Climate
Delaware experiences four distinct seasons, which greatly influences the growing cycle of kohlrabi. This vegetable prefers cooler temperatures ranging from 55°F to 75°F. In Delaware, you can successfully grow kohlrabi during both spring and fall seasons to take advantage of these cooler conditions.
Soil Requirements
Kohlrabi thrives in well-drained, fertile soil with a pH level between 6.0 and 7.0. The soil should be rich in organic matter; compost or well-rotted manure can enhance its fertility and drainage capabilities. Before planting, test your soil using a home test kit or by sending a sample to your local agricultural extension office for analysis.
Sunlight
Choose a location that receives full sun for at least six hours a day. While kohlrabi can tolerate partial shade, it will grow best with ample exposure to sunlight.
Preparing Your Garden Bed
Soil Preparation
- Clear the Area: Remove any weeds or debris from the garden bed where you plan to plant kohlrabi.
- Till the Soil: Use a garden fork or tiller to loosen the soil to a depth of about 12 inches. This helps aerate the soil and improve drainage.
- Amend the Soil: Mix in compost or aged manure at least two weeks before planting. This amendment enriches the soil and provides essential nutrients for healthy growth.
Raised Beds vs. In-Ground Planting
If your native soil is heavy clay or sandy with poor nutrient content, consider building raised beds filled with quality topsoil and compost. Raised beds offer better drainage and can extend your growing season by warming up faster in early spring.
Sowing Seeds
When to Plant
For spring planting in Delaware, sow seeds indoors about 4-6 weeks before the last expected frost date (typically mid-April). For fall planting, start seeds indoors again around late July to early August.
Direct Seeding
You can also directly sow seeds outdoors once the soil temperature reaches at least 45°F:
- Spring Planting: Sow seeds ½ inch deep and 3-4 inches apart in rows spaced 12-18 inches apart.
- Fall Planting: Follow similar spacing guidelines as spring planting.
Transplanting Seedlings
If you started your seeds indoors, harden off your seedlings by gradually exposing them to outdoor conditions over a week. Once they have acclimated, transplant them into your garden bed with spacing of about 6-8 inches apart each way.
Caring for Your Kohlrabi Plants
Watering
Kohlrabi needs consistent moisture throughout its growing period to ensure proper growth and prevent bitterness:
- Watering Schedule: Aim for at least 1 inch of water per week. Adjust based on rainfall and consider deeper watering sessions to encourage root development.
- Mulching: Apply a layer of organic mulch around the base of the plants to retain moisture and suppress weeds.
Fertilization
Kohlrabi benefits from additional feeding throughout its growth cycle:
- Initial Fertilization: Incorporate a balanced fertilizer (like 10-10-10) into the soil at planting time.
- Side Dressing: After about four weeks of growth, apply another round of fertilizer along the rows without disturbing the roots.
Weeding
Keep your garden bed free from weeds as they compete for nutrients and water:
- Hand weed regularly or use mulch to suppress weed growth.
- Be cautious when using herbicides; ensure they are safe for vegetables if you choose this method.
Pest Management
Kohlrabi is susceptible to various pests that can hinder its growth:
Common Pests
- Aphids: Small green insects that suck plant sap.
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Control by washing them off with water or using insecticidal soap.
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Cabbage Worms: Larvae of moths that chew on leaves.
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Handpick or use row covers to protect young plants.
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Flea Beetles: Tiny pests that create small holes in leaves.
- Prevent damage by applying diatomaceous earth around plants or using floating row covers.
Disease Prevention
Keep an eye out for diseases such as downy mildew or powdery mildew:
- Ensure good air circulation around plants by not overcrowding them.
- Rotate crops each year to prevent soil-borne diseases.
Harvesting Kohlrabi
Timing is key when it comes to harvesting kohlrabi:
- Harvesting Timeframe: Usually ready for harvest 50-60 days after sowing seeds.
- Ideal Size: The optimal size for harvesting is about 2-3 inches in diameter; at this size, the texture is crisp and tender.
- How to Harvest: Cut the stem just below the bulb with sharp garden shears or a knife.
Storing Your Kohlrabi
To prolong freshness post-harvest:
- Remove any leaves from the bulbs but leave about an inch of stem intact.
- Store kohlrabi in a cool place (ideally between 32°F – 40°F) and high humidity such as in a crisper drawer of your refrigerator.
- Fresh kohlrabi can last several weeks when stored properly.
Conclusion
Growing kohlrabi in Delaware can be an enjoyable and fruitful endeavor for gardeners seeking something different from traditional vegetables. With proper preparation, care, and attention to pest management, you can cultivate healthy kohlrabi plants that yield delicious results for your kitchen table. Embrace this unique vegetable and experiment with various recipes—it may just become a staple in your culinary repertoire!