Kohlrabi

Plant Overview

Kohlrabi (Brassica oleracea var. gongylodes) is listed in the Brassicaceae family and categorized as a vegetable with a biennial commonly grown as an annual crop life cycle. This profile summarizes growing information for hardiness, light, soil, water, seed starting, maturity, and other available cultivation details. Difficulty is listed as Easy.

Plant ID

PLT-0047

Family

Brassicaceae

Plant type

Vegetable

Life cycle

Biennial commonly grown as an annual crop

Alternate names

German turnip, turnip cabbage, knol-kohl

Growth habit

Compact cool-season vegetable with a rounded, swollen above-ground stem bearing stalked leaves; overwintered plants produce taller flowering stems

Mature height

Standard compact varieties commonly reach about 9-12 inches during the edible harvest stage; larger varieties and flowering plants can grow taller

Mature spread

About 9-12 inches for standard compact varieties; allow more room for giant varieties and seed-producing plants

Difficulty

Easy

Growing Conditions

Kohlrabi is listed for full sun conditions. Water needs are listed as moderate; keep evenly moist without waterlogging. The database soil reference is Fertile, well-drained soil with organic matter. The listed soil pH range is 6.0-7.0, and the listed hardiness range is 2-11 as an annual crop.

Hardiness zones

2-11 as an annual crop

Sunlight

Full sun

Soil

Fertile, well-drained soil with organic matter

Soil pH

6.0-7.0

Water needs

Moderate; keep evenly moist without waterlogging

Plant spacing

Space standard varieties about 6 inches apart in rows 12 inches apart; follow variety-specific spacing for larger types

Seed & Germination

For seed starting, the listed germination time is Usually 3-10 days under suitable conditions and the seed depth is Sow about 1/4-1/2 inch deep. The listed time to maturity is Variety-dependent: early varieties may list 35-45 days to harvest, while giant types can take about two months. Check whether seed packet timing begins at sowing or transplanting. Use these values as general reference points and adjust for local climate, seed source, and growing conditions.

Germination

Usually 3-10 days under suitable conditions

Germination temperature

Seeds can be started indoors without a heating mat; room temperatures around 60-70 F are suitable for raising seedlings

Seed depth

Sow about 1/4-1/2 inch deep

Sowing method

Direct sow or use young transplants during the cool growing season; avoid scheduling stem development for hot weather

Start indoors

Allow about 5-6 weeks to grow transplants with 4-6 developed leaves

Transplanting

Set out seedlings with 4-6 developed leaves and a healthy root system; protect young plants from hard frost

Harvest & Propagation

Days to maturity

Variety-dependent: early varieties may list 35-45 days to harvest, while giant types can take about two months. Check whether seed packet timing begins at sowing or transplanting

Harvest

Harvest standard varieties when the swollen above-ground stem is about 2-3 inches across, before it becomes woody. Follow the seed supplier harvest size for giant varieties; young leaves are also edible

Propagation

Propagated by seed, either directly sown or raised as transplants

Seed saving

Overwinter healthy plants with roots and growing points intact to allow flowering in the second season. Isolate from other flowering Brassica oleracea crops. For long-term variety maintenance, save seed from 20-50 plants. Collect dry brown pods before they split, then thresh and clean the seed; store fully dried seed in a cool, dry place.

Pollination

Insect-pollinated and generally self-incompatible; grow multiple compatible flowering plants for seed. Can cross with other Brassica oleracea crops, including cabbage, broccoli, cauliflower, kale, and Brussels sprouts

Garden Information

Common pests

Aphids, cabbage loopers, cutworms, flea beetles, and cabbage worms

Common diseases

Downy mildew and bacterial rots can affect kohlrabi

Uses

Peeled swollen stems eaten raw in salads or slaws, or cooked in soups, roasted dishes, and fritters; young leaves can be cooked as greens