Radish
Raphanus sativus
Brassicaceae · cabbage family
- Matures
- 20–60 days
- Harvest
- Once · Annual
- Sun
- 4–8+ hrs
- Spacing
- 1 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 | ● | ● | ● | ● | ● | ● |
Sunlight
How well it does at each level of direct sun per day.
Soil depth
Root room it needs — useful for sizing raised beds and containers.
Spacing
Room each plant needs — along the row and between rows — for sizing beds.
- In-row
- 1 in
- Between rows
- 6 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
- 4–20 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
- Direct-sow
Sown straight into the bed it will grow in.
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
- 65–85°F
- Sow depth
- 0.5 in
- Time to emerge
- 4–6 days
Germinates between 40–95°F; happiest around 65–85°F.
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
Cucumber Beetles
- What it is
- Adult beetles are shiny with black heads, long antennae, and about 1/4 inch long. Adults may be striped or spotted, depending upon species.
- What you'll see
- Adults feed on the leaves of many vegetables as well as on soft fruit. Shoots and blossoms may also be consumed.
- What to do
- Management of cucumber beetles is difficult. The best strategy for most vegetable gardens may be to place protective cloth over emerging plants and remove it when plants are old enough to tolerate damage.
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.
Harlequin Bug
- What it is
- Harlequin bugs can be confused with Bagrada bugs, an invasive species, but are much larger and lack the white markings characteristic of Bagrada bugs. Harlequin bugs may also be confused with stink bugs.
- What you'll see
- Harlequin bugs suck fluids from plant tissue. They leave yellow or white blotches on areas of leaves where they have been feeding; heavy infestations can cause plants to wilt, turn brown, and die.
- What to do
- Handpick bugs or their eggs. Destroy old cole crop plants and mustards because they provide breeding areas.
Sources
Every figure above is backed by these.
- UC Master Gardeners, San Mateo–SF Countiesbacks plantingWindow, startMethod · Foggy & Sunny calendars, Radish / Radish (small) rows: seed year-round (foggy) and Feb-Sep plus Jan & Oct-Dec small types (sunny). Start method: Foggy & Sunny calendars, Radish row: (S) sow seed only.
- Golden Gate Gardening (Pam Peirce)backs plantingWindow, sunlight, lifecycle, harvestStyle · Foggier/Sunnier planting-times charts, Radish (small) row; tolerates part shade. Habit and harvest: annual, once — from this source's entry for this crop.
- UC Master Gardeners, Santa Clara County (Containers)backs soilDepth · Soil-depth-by-crop, shallow-rooted (6-9 in): radishes.
- UC Master Gardeners, Sonoma County (Planting Summary)backs daysToMaturity, inRowSpacing, rowSpacing, startMethod · Vegetable Planting Summary, Radishes row: 20-60 days, 1 in in-row spacing. Between-row spacing 6 in (Radishes row). Start method: Vegetable Planting Summary, Radishes row: method D (usually direct-sown).
- UC Master Gardeners, Sacramento County (Germination)backs germination · GN 154 soil-temp table, radishes row: 40/65–85/95°F; germinationDays 4–6 derived from Table 2 across the optimum band.
- USDA GRIN Taxonomybacks botany
- Colorado State University Extension (Master Gardener)backs plantingDepth · Table 1 Cool Season, Radishes row: 1/2 in.
- Royal Horticultural Society (RHS)backs growthHabit · Raphanus sativus (radish): 'Ultimate height 0.1-0.5 metres' and 'Ultimate spread 0.1-0.5 metres' (0.1-0.5 m = 4-20 in). Low leafy rosette of tops, wider than tall, no support (low-mound).
- UC Master Gardeners, Santa Clara Countybacks startMethod · Start method: Planting chart: Radishes carry a Direct seed row only, From seed to transplant Not applicable.