GardenBiennial Plant · zones 2–11 · 15 varieties
Kohlrabi
Brassica oleracea Kohlrabi Group
Brassicaceae — the same plant family as cabbage, radish, broccoli, cauliflower and 12 more here. Relatives share pests and diseases, which is why rotation plans group by family.
Kohlrabi (Brassica oleracea Kohlrabi Group) is a biennial plant for USDA zones 2–11. It wants full sun and pH 6–7.5 soil, with about 1–2 in of water weekly. It matures in about 40–60 days from sowing. Watch for aphids and alternaria leaf spot. Below: its full sourced profile from 7 extension sources, plus a planting calendar timed to your frost dates.
Typical dates for zone 6b — set your zone or ZIP for yours. This calendar assumes the crop is started indoors. Timing is a guide from the crop's sourced growth stages; confirm with your local frost dates and extension before you sow.
What we will not put a number on
We do not give a feeding rate for this crop, and that is deliberate rather than a gap. The figures published by extension services are pounds of nitrogen per acre for a production field — they do not convert safely to a raised bed or a pot without knowing your soil test and your fertilizer's analysis, and guessing errs toward burning roots. It is also why every chart you find online disagrees with the next one.
We give watering as a depth per week rather than gallons per plant, because that is how it is actually measured and how the published figures are written. A gallons-per-plant number depends on your spacing, your soil and whether the plant is in a pot — so it would look more precise than it is.
Site & soil
- Hardiness zones
- 2–11
- Sun
- Full sun
- Soil pH
- 6–7.5
- Soil texture
- Loam, Well drained
- Frost tolerance
- Half hardy
- Suffers in days above
- 80 °F
- Runs to seed after cold nights below
- 50 °F
No published figure for the temperature frost starts to hurt it and the temperature that would kill it. We looked — where a number is missing here it is missing from the research, not skipped. The crop’s frost and heat tolerance above still applies.
The plant
- Mature height
- 9–12 in
- Mature spread
- 9–12 in
- Growth rate
- Moderateest
- Spacing in row
- 4–6 in
- Between rows
- 12–24 in
- Planting depth
- 0.25–0.5 in
- Support
- Self-supportingest
- Grown from
- Direct sow, Transplant
There is no line here for a container size, because we have no figure to put there. We went looking and wrote down what we read — it is missing on purpose, not because nobody checked.
Water & feeding
- Water needs
- Moderate
- Water per week
- 1–2 in/wk
- Critical water
- Bulbingest
- Feeding
- Moderate
Timing & fruiting
- Days to maturity
- 40–60 days from seed
- Harvest cues
- Bulb shoulder visible
Planted again for autumn
- Sow by
- mid Sep typical · zone 6b
40 days to maturity from sowing, counted back from the first frost above. Not published for anywhere in particular: it is your own frost date and this crop's own figure, which is why it works wherever you are. A days-to-maturity figure is a catalog number for a good season rather than a promise, and a cold month moves it.
Edible parts per source: stem, leaf.
Compiled from the extensions cited below. Which ones actually show up depends on your region — your extension's local list is the last word.
Open one and add it to your garden — it lights up here. The rest of the 15 are in the full list below.
| Variety | Type | Days | Color | What it is known for |
|---|---|---|---|---|
| Azur Star | Purple | 48 | Purple | |
| Delicacy Purple | Purple | 65 | Purple | |
| Delicacy White | Green | 60 | Green | |
| Early Purple Vienna Heirloom | Purple | 60 | Purple | |
| Early White Vienna Heirloom | Green | 50 | Green | |
| Gigante | Giant | 130 | Green | Fedco Seeds describes this askeeps a long time after picking |
| Grand Duke F1 | Green | 45–50 | Green | |
| Kolibri F1 | Purple | 45 | Purple | |
| Konan F1 | Green | 43 | Green | |
| Korist F1 | Green | 42 | Green | |
| Kossak F1 | Giant | 80 | Green | Johnny's Selected Seeds describes this askeeps a long time after picking |
| Superschmelz Heirloom | Giant | 70 | Green | Territorial Seed Company describes this askeeps a long time after picking |
| Sweet Vienna | Green | 45 | Green | |
| Terek F1 | Green | 40 | Green | |
| Winner F1 | Green | 45 | Green |
- Harvest to Table
- Johnny's Selected Seeds
- Missouri Botanical Garden
- NC State Extension
- University of Minnesota Extension
- Utah State University Extension
We compile bare facts from these university-extension and horticultural sources, never copied prose. 18 of the 21 values on this page carry a citation. The rest are marked est; hover one and it says why — either nobody publishes a figure we could point at, or a person set it and attached no source. Figures vary with climate and seed source; confirm with your local extension before you buy.
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