key growing information

Growing Kohlrabi From Seed

How to grow kohlrabi from seed: cool-season timing, soil, transplants or direct sowing, spacing for fresh or storage types, disease prevention and harvest size.

By Hensley’s Seed Co. September 3, 2026

Kohlrabi - Key Growing Information

A fresh-eating kohlrabi variety, being held in the field until harvest-time.

SCIENTIFIC NAME:

Brassica oleracea var. gongylodes

CULTURE:

Kohlrabi likes mild to cool weather: grow it all season in the North and through fall and winter in the South. Fertile, well-watered soil with a pH of 6.0–7.5 keeps it growing fast, which gives sweeter, better-flavored bulbs.

DAYS TO MATURITY:

Counted from direct sowing; take off about 14 days for transplants.

TRANSPLANTING:

For the earliest harvest, start seed 4–6 weeks before planting out, 3–4 seeds per inch in open flats or 2 per cell in cell flats (thinned to one). Set plants 4–5" apart, or 10" apart for 'Kossak'.DIRECT SEEDING: Plant ¼–½" deep at 15 seeds per foot in rows 12–18" apart. Thin fresh-market types to 4" and storage types to 10".

AVG. DIRECT SEEDING RATE:

At 15 seeds per foot in rows 18" apart: 250 seeds sow about 16', 1,000 seeds about 66'; plan on roughly 436,000 seeds per acre.

DISEASES:

Prevention is the best approach: (1) rotate with non-brassica crops for several years, (2) use clean seed-starting mix and seedbeds, and (3) keep tools and fields clean. Select kohlrabi seed lots that tested negative for black rot (Xanthomonas campestris pv. campestris) and black leg (Phoma lingam). HARVEST: Harvest bulbs at about 2–3" across, or about 8" for storage varieties.

SIZED SEEDS:

Standard seed unless noted.

TRANSPLANTS (AVG.):

About 4,500 transplants per oz., or 800 per 1,000 seeds. SEEDS/OZ. (AVG.): 6,200.

PACKET:

100 seeds per packet, enough for about 8'.