Kohlrabi
Brassica oleracea var. gongylodes
Brassicaceae · cabbage family
- Matures
- 50–70 days
- Harvest
- Once · Annual
- Sun
- 6–8+ hrs
- Spacing
- 4–6 in
Planting window
When to sow, by microclimate — foggier blocks run a different calendar than sunnier ones.
| Jan | Feb | Mar | Apr | May | Jun | |
|---|---|---|---|---|---|---|
| Foggy | ● | ● | ● | ● | ● | ● |
| Sunny | ● | ● | ● |
| Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|
| Foggy | ● | ● | ||||
| Sunny | ● | ● | ● | ● |
Well-suitedMarginalNot suited
Sunlight
How well it does at each level of direct sun per day.
<2 hrsNot suited
2–4 hrsNot suited
4–6 hrsMarginal
6–8 hrsWell-suited
8+ hrsWell-suited
Well-suitedMarginalNot suited
Soil depth
Root room it needs — useful for sizing raised beds and containers.
6–10"Well-suited
10–15"Well-suited
15–18"Well-suited
18–24"Well-suited
Well-suitedMarginalNot suited
Spacing
Room each plant needs — along the row and between rows — for sizing beds.
- In-row
- 4–6 in
- Between rows
- 12 in
Growth habit
The shape it makes in the bed and how tall it gets — what tells you whether to give it a trellis, a stake, or just room.
- Habit
- Low mound
- Mature height
- 9–12 in
Low and self-supporting — no staking needed.
How to start it
Sow it where it grows, or raise it under cover and set it out — and how far ahead to start the seedlings if it's the latter.
- Usually
- Transplant
- Start indoors
- 6 weeks ahead
Direct-sowWell-suited
TransplantWell-suited
Started under cover, then set out as a seedling.
Well-suitedMarginalNot suited
Getting started
How it goes in the ground — how deep to sow or set it, and the soil temperature it needs to wake up. The cold-soil floor is the real limiter for direct-sowing in a foggy SF spring.
- Started from
- From seed
- Ideal soil temp
- 45–85°F
- Sow depth
- 0.5 in
- Time to emerge
- 4–7 days
Germinates between 40–85°F; happiest around 45–85°F.
30°F110°F
IdealWorkable
Pests & diseases
What tends to trouble this crop — what it is, what you'll see, and what to do about it, least-toxic first.
Pests3
Aphids
- What it is
- Aphids have soft pear-shaped bodies with long legs and antennae and may be green, yellow, brown, red, or black depending on the species and the plants they feed on. A few species appear waxy or woolly due to the secretion of a waxy white or gray substance over their body surface.
- What you'll see
- Low to moderate numbers of leaf-feeding aphids aren't usually damaging in gardens or on trees. However, large populations can turn leaves yellow and stunt shoots; aphids can also produce large quantities of a sticky exudate known as honeydew, which often turns black with the growth of a sooty mold fungus.
- What to do
- Before planting vegetables, check surrounding areas for sources of aphids and remove these sources. On the other hand, these aphid-infested weeds can sometimes provide an early source of aphid natural enemies.
Cabbage Worms and Loopers
- What you'll see
- Worms and loopers are light to dark green. Adult loopers are gray or brown moths while cabbage worms are white butterflies. Worms and loopers chew holes in leaves and hide in kale heads.
- What to do
- Control worms and loopers with appropriate insecticides or biological measures.
Flea Beetles
- What it is
- Their small size, enlarged back legs, characteristic shot-hole damage, and habit of jumping when disturbed make flea beetles easy to identify. There are numerous flea beetle species.
- What you'll see
- Adults feed mostly on leaves, leaving tiny pits or small holes at their feeding sites. Flea beetles feeding together can cover leaves with bleached, pitted areas or ragged holes.
- What to do
- Remove debris in the fall to remove any overwintering beetles. Reflective mulches applied very soon after planting and before plants become infected can be helpful.
Sources
Every figure above is backed by these.
- UC Master Gardeners, San Mateo–SF Countiesbacks plantingWindow, startMethod · Foggy & Sunny calendars, Kohlrabi row (transplant): foggy Jan-Aug; sunny Feb-Apr & Jul-Oct. Start method: Foggy & Sunny calendars, Kohlrabi row: (T) transplant only — the SF-calibrated source, hence transplanting taken as usual.
- UC Master Gardeners, Sonoma County (Planting Summary)backs daysToMaturity, inRowSpacing, rowSpacing, startMethod · Vegetable Planting Summary, Kohlrabi row: 50-70 days, 4-6 in in-row spacing. Between-row spacing 12 in (Kohlrabi row). Start method: Vegetable Planting Summary, Kohlrabi row: method D/T — either method works.
- Utah State University Extensionbacks soilDepth, inRowSpacing, daysToMaturity · 'How to Grow Kohlrabi in Your Garden' (USU Extension): 'roots are shallow' (shallow-rooted); '6 inches between plants in the row' (corroborates spacing); varieties 40-60 days (corroborates days-to-maturity).
- Golden Gate Gardening (Pam Peirce)backs sunlight, lifecycle, harvestStyle · Kohlrabi is a full-sun-preferring cole crop (Brassica oleracea) that tolerates part shade. Habit and harvest: annual, once — from this source's entry for this crop.
- Cornell University Home Gardeningbacks germination · Cornell kohlrabi: germination 45–85°F, as low as 40°F; emergence 4–7 days
- USDA GRIN Taxonomybacks botany
- Colorado State University Extension (Master Gardener)backs plantingDepth · Table 1 Cool Season, Kohlrabi row: 1/2 in.
- Missouri Botanical Garden Plant Finderbacks growthHabit · Plant Finder, Brassica oleracea (Gongylodes Group): Height '0.75 to 1.00 feet' (9-12 in); a low plant of 'fat, rounded, turnip-like enlargements of the stem just above the soil surface' with leafy tops (low & compact = low-mound).
- UC Master Gardeners, Santa Clara Countybacks startMethod · Start method: Planting chart: Kohlrabi carries both rows; From seed to transplant 6 weeks.