A fast cabbage-family vegetable grown for its swollen stem — a crisp bulb that sits above the soil and eats like a sweeter, milder broccoli stalk.
Brassica oleracea var. gongylodes · also called German turnip, Turnip cabbage
Windows are counted from the average date of your last spring frost.
Ready in roughly two months, it works at both cool ends of the season and holds in the refrigerator for weeks without going limp. Raw slices are juicy and mild; roasted, the flesh turns sweet.
A little history. The bulb is a thickened stem, not a root, and forms above the soil line where the plant stores water and sugars. Same species as cabbage and kale, selected for stem swelling.
Sow seeds ½ inch (13 mm) deep, and aim for 6 inches (15 cm) between plants once thinned. Cover seed ½ inch and keep the top half-inch damp until sprouts show. Break any dry crust with a light watering. Seedlings emerge in 4–10 days.
Either — shallow-rooted and content in 8–10 inches of soil depth. In containers: 3-gallon pot per plant, or a 10-inch-deep trough for a short row.
Water steadily, roughly twice a week in warm weather. Water when the top inch of soil feels dry. Aim for about 1 inch per week including rain.
Feed at planting, then side-dress once when bulbs reach golf-ball size. What to use: compost plus a balanced 5–5-5 organic fertilizer.
No pruning. Pull off yellowing lower leaves so air moves around the bulb, and leave the top rosette intact — those leaves size the stem.
It's ready when bulbs are 2–3 inches across for standard varieties — tennis-ball size at most. Larger than that and the flesh turns fibrous and woody. Cut the stem with a knife just below the bulb, at soil level, rather than pulling. Trim leaves off immediately, keeping the smaller inner leaves for cooking.
Trim leaves, leave the bulb unpeeled, and refrigerate in a loose bag for 4–6 weeks. Storage varieties keep 3–4 months in a cold, humid cellar.
Sow a short row every 2–3 weeks through spring and again in late summer; each planting holds only a couple of weeks at good size.
In mild-winter areas, mulch plants deeply with straw and harvest through winter. Any plant left to overwinter flowers the second spring instead of bulbing.
Beet
Kohlrabi feeds in the top few inches while beets pull from a deeper taproot, so the two can share a bed without fighting over the same water. Harvesting kohlrabi at soil level also leaves beet roots undisturbed.
Onion
The strong smell of onion foliage can make it harder for cabbage moths and root maggot flies to locate kohlrabi by scent. The effect is real but partial — treat it as a supplement to row cover, not a replacement.
Dill
Dill flowers draw in hoverflies, lacewings, and the tiny parasitic wasps that attack cabbageworms and aphids. Let a couple of plants flower at the row end rather than harvesting all the foliage.
Sweet Alyssum
A low edging of sweet alyssum flowers continuously and feeds adult hoverflies, whose larvae eat cabbage aphids. It stays short enough that it never shades the developing bulbs.
Nasturtium
Aphids often settle on nasturtium stems in preference to kohlrabi. It only helps if you check the nasturtiums weekly and cut off and destroy the infested shoots before the colony spreads.
Lettuce
Both want the same cool weather and steady moisture, and lettuce fills the gaps between young kohlrabi plants before the leaf rosettes spread. Cut the lettuce first and the kohlrabi takes over the space.
Bell Pepper
Old companion charts keep kohlrabi away from peppers, with no mechanism ever demonstrated. The practical issue is timing and light: peppers want the heat that turns kohlrabi woody, and their bushy growth shades a crop that needs full sun.
Hot Pepper
The same long-standing chart pairing applies to hot peppers, and it is said to hold both ways. Neither crop is harmed by proximity as far as anyone has shown — but their seasons and sun needs simply do not line up.
Tomato
Gardeners have long separated kohlrabi and tomatoes, and no mechanism has been demonstrated. What is observable is competition: a caged tomato casts heavy shade and takes the water kohlrabi needs for steady, tender bulb growth.
Pole Bean
Old charts keep these apart without giving a reason that holds up. Practically, a bean trellis shades the row and picking beans means constant traffic over shallow kohlrabi roots.
Fennel
Fennel roots release substances that reliably stunt most garden vegetables, kohlrabi included. Grow it in its own corner or a pot — well apart, its flowers still feed hoverflies and tiny parasitic wasps.
Strawberry
Old charts keep strawberries and cabbage-family crops apart, with no mechanism established. A real concern is that a permanent strawberry patch cannot be rotated, which works against the 4-year gap kohlrabi needs.
Give the cabbage family 4 years away from this spot before any of its relatives return.
The tomato family, the pea and bean family or the carrot family thrive in this ground next season.
A heavy feeder that leaves little behind — follow it with peas or beans to rebuild nitrogen, or with tomatoes, peppers, carrots, or parsnips. Keep all cabbage-family crops out of this bed for 4 years to hold down clubroot and black rot.
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