Growing Kohlrabi: A Complete Profile
By Growing Home Greens Team · July 18, 2026
Kohlrabi looks like nothing else in the garden: a pale green or purple bulb that swells right at the soil line, with leaves shooting out of it like a small alien plant. It’s mild, crisp, and closer to a cross between broccoli stem and jicama than anything most people expect from a brassica.
Watching the bulb swell in plain view
Kohlrabi can be started indoors or direct-sown, and at 55 days it moves at a similar pace to other quick brassicas. The bulb itself forms just above the soil surface, so unlike a root crop, you’re watching it swell in plain view rather than guessing at what’s happening underground. Consistent watering keeps the texture crisp; a bulb that goes through drought and rebound stress is more likely to turn woody.
Harvest at the size the variety is meant for
Bulbs left in the ground too long, especially with the larger “giant” storage varieties, get fibrous and tough regardless of watering. Harvest at the size the variety is meant for rather than waiting for it to get bigger, a standard-season variety like Grand Duke is best picked at a few inches across, not left to bulk up indefinitely.
Compatible with beets, not with tomatoes
Kohlrabi shares compatible nutrient needs with beets and is a common bed-sharing pair. See the full companion guide for kohlrabi. Keep it away from tomatoes and beans, which are reported to stunt each other’s growth when planted too close. At 4 per square foot, it’s dense enough to fit efficiently into the Garden Designer’s grid without dominating a bed.
Companion planting guide for Kohlrabi · Find your planting dates
Typically viable in USDA zones 2-11. Not sure your zone? Look it up by ZIP code.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Kohlrabi tolerates either.
See exact start-indoors, direct-sow, and harvest dates for your zone →
How many Kohlrabi plants fit per square foot?
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 1-1.5 ft.
Varieties worth considering
- Grand Duke (F1): Rated 5.0 stars in Cornell Cooperative Extension's grower variety database, with reviewers noting the 4-inch bulbs stay tender and don't turn fibrous at 50 days to maturity, a reliable pick for a standard-season planting rather than a giant storage type. (source)
- Kolibri: Cornell rates it 4.7 stars, a vivid purple hybrid with crisp, nearly fiberless white flesh at 43-45 days. The variety to grow if you want the color contrast for a mixed bed, not just the standard pale green bulb. (source)
- Kossack: A genuine giant storage type Cornell rates 4.5 stars, bowling-ball sized and, unlike most large kohlrabi, still tender rather than woody at that size. The exception to the harvest-small rule below, but only for this specific variety. (source)
Cited from the source shown next to each variety. We haven't grown these ourselves yet, so treat this as a research-backed starting point, not a personal endorsement.
Where to buy kohlrabi seeds
As an Amazon Associate we earn from qualifying purchases. Some links on this page also go to other retailers we may earn a commission from as an affiliate, at no extra cost to you. We only recommend products with a genuine consensus of positive, independent reviews. See the sources cited on each item.
See it growing
Search YouTube for "growing kohlrabi" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
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Growing Kohlrabi: The brassica that swells into an edible bulb above ground, and why picking the right variety size matters more than with most crops.
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