White kohlrabi growing guide for fall harvest lovers wanting mild sweet brassica root flavor

For a mild, sweet brassica root flavor perfect for fall harvests, focus on white kohlrabi. This guide is tailored for gardeners seeking this specific taste profile and harvest time.

Start your white kohlrabi seeds indoors 4-6 weeks before your last expected spring frost if you aim for a summer harvest, but for a fall harvest, direct sow seeds outdoors in mid to late summer, approximately 6-8 weeks before your first expected fall frost. This staggered planting ensures the kohlrabi matures in cooler weather, which enhances its sweetness and prevents bolting. Aim for a soil temperature of at least 50°F (10°C) for germination.

Choose a location that receives at least 6 hours of direct sunlight per day. While kohlrabi tolerates partial shade, full sun generally leads to better bulb development and sweeter flavor. Ensure the soil is well-draining and rich in organic matter. Amend your soil with compost or well-rotted manure before planting to improve fertility and structure. Aim for a soil pH between 6.0 and 7.0.

Loosen the soil to a depth of at least 8 inches. Incorporate a generous amount of compost, aiming for a soil rich in nutrients. This will provide the steady feeding kohlrabi needs for rapid, tender growth. Avoid soils that are too heavy or compacted, as this can lead to misshapen bulbs and hinder nutrient uptake.

If starting indoors, transplant seedlings into the garden after the danger of frost has passed for spring planting, or in mid-to-late summer for fall. Harden off seedlings gradually by exposing them to outdoor conditions for a week before transplanting. Plant them at the same depth they were in their pots, or slightly deeper, ensuring the leaves are above the soil line. For fall harvests, sow seeds directly into the prepared garden bed. Plant seeds about 1/2 inch deep and 1 inch apart. Once seedlings emerge and have a few true leaves, thin them to stand 4-6 inches apart. Closer spacing can result in smaller bulbs, while wider spacing allows for larger, potentially milder bulbs.

Consistent moisture is crucial for tender, sweet kohlrabi. Water deeply and regularly, especially during dry spells. Aim to keep the soil consistently moist but not waterlogged. A good watering practice is to provide about 1 inch of water per week, either from rainfall or irrigation. Mulching around the plants helps retain soil moisture and suppress weeds. Use organic mulches like straw or shredded leaves.

Kohlrabi is a relatively heavy feeder. About 3-4 weeks after transplanting or thinning, apply a balanced fertilizer or a side dressing of compost. Look for fertilizers with a higher nitrogen content to encourage leafy growth and bulb development. Avoid over-fertilizing with nitrogen late in the season, as this can lead to a bitter taste.

These caterpillars can decimate kohlrabi leaves. Handpick them off as you see them. For larger infestations, consider using organic insecticides like Bacillus thuringiensis (Bt) or neem oil. Row covers can also be effective barriers. These tiny black beetles chew small holes in the leaves. Row covers are the best preventative measure. If infestation is severe, a light dusting of diatomaceous earth can help.