Radish
Raphanus sativus
The fastest crop most gardeners grow — usable four to six weeks from sowing — which makes it the obvious thing to sow with a child, and the obvious way to test whether a new bed or a windowsill setup actually works before committing a season to it. Its one failing is that it will not wait: left too long the roots go hot, woody and hollow.
- Position
- Full sun or Partial shade
- Water
- moderate demand
- Drainage
- Free-draining, Moisture-retentive
- Grows to
- 15–20 cm × 10 cm
- Hardiness
- H4
- Difficulty
- Straightforward
Described view
A short row of salad radishes with red shoulders pushing above the soil surface among their bristly leaves
August
Sow outdoors · Harvest
Radish’s year
Resolved for United Kingdom (general). Every window is stored against a climate event rather than a date, so a late frost pocket runs later than the band shows. What else August calls for.
| Activity | J | F | M | A | M | J | J | A | S | O | N | D |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sow outdoors | March. | April. | May. | June. | July. | August. | September. | |||||
| Harvest | April. | May. | June. | July. | August. | September. | October. |
Names that cause confusion
radish — Winter radish, mooli and daikon are the same species grown as large long-season roots, and behave quite differently from the quick salad radish described here.
Timing that travels
The band above resolves this plant's windows into months for one region. These are the windows themselves, stored against a climate event rather than a date — which is the form that survives being carried to a colder garden, a frost pocket, or next year.
- Sow outdoors0–24 weeks after the soil becoming workable, every two weeks — a fortnightly pinch of seed beats one large sowing
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Radishes — sowing
Checked 2026-08-13
- Harvest4–28 weeks after the soil becoming workable, four to six weeks after each sowing
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Radishes — harvesting
Checked 2026-08-13
Conditions it needs
- Light
- Full sun, Partial shade
- Direct sun
- 4 hours a day or more
- Frost
- Hardy
- Hardiness rating
- H4 (RHS)
- Grows best at
- 10–20 °C
- Germinates at
- 7–30 °C
- Soil
- Loam, Sandy, Peat-free compost
- Soil pH
- 6–7
- Drainage
- Free-draining, Moisture-retentive
- Water needs
- moderate
- Drought
- poor tolerance
- Waterlogging
- moderate tolerance
- Heat
- poor toleranceHorticultural consensusDepends on conditions
- Wind and exposure
- good tolerance
Where these figures come from
- LightSourced guidancehigh confidence
One of the few crops that genuinely prefers some shade in midsummer, when full sun makes it bolt.
- Royal Horticultural Society: Radishes — position
Checked 2026-08-13
- Direct sunHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- FrostSourced guidancehigh confidence
- Royal Horticultural Society: Radishes — hardiness
Checked 2026-08-13
- Hardiness ratingSourced guidancehigh confidence
- Royal Horticultural Society: RHS hardiness ratings
Checked 2026-08-13
- Grows best atHorticultural consensusmoderate confidence
- Home and Garden Information Center — Clemson Cooperative Extension: Radish — culture
Checked 2026-08-13
- Germinates atSourced guidancehigh confidence
- OSU Extension Service — Oregon State University: Vegetable seed germination temperatures
Checked 2026-08-13
- SoilHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Soil pHSourced guidancehigh confidence
- University of Minnesota Extension — University of Minnesota: Soil pH for vegetable crops
Checked 2026-08-13
- DrainageHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Water needsHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- DroughtHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- WaterloggingHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- HeatHorticultural consensusDepends on conditionsmoderate confidence
Applies when: Heat and long days make radishes bolt and turn the roots hot and pithy.
No external citation — see the evidence type above.
Checked 2026-08-13
- Wind and exposureHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
On your soil
Computed by comparing this plant's recorded requirements against each soil's recorded characteristics. A recorded horticultural fact overrides the comparison where GrowingHQ holds one.
| Soil | Verdict | Why |
|---|---|---|
| Heavy clay | Works, with one condition | Radish will crop on heavy clay, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse. |
| Sandy | Works, with one condition | Radish will crop on sandy, but one thing has to be dealt with first. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering.Water and mulch will carry it through. On this soil the watering is not optional in a dry spell, which is the difference between a crop and a failure. |
| Chalky and alkaline | Struggles here | Radish struggles on chalky and alkaline: The soil is substantially too alkaline for it: it wants pH 6 to 7, and this soil sits around 7.8 to 8.5. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering. A container or a raised bed of imported soil sidesteps the problem entirely. |
| Loam | Prefers this soil | Loam suits Radish as it stands: The pH suits it: it wants 6 to 7, and this soil is in that range. The free drainage is exactly what it wants. Loam is among the soils it is recorded as suiting. The soil holds moisture, which saves a great deal of watering. There is ample rooting depth for it. |
| Silty | Prefers this soil | Silty suits Radish as it stands: The pH suits it: it wants 6 to 7, and this soil is in that range. The free drainage is exactly what it wants. The soil holds moisture, which saves a great deal of watering. There is ample rooting depth for it. |
| Peaty and acid | Works, with one condition | Radish will crop on peaty and acid, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse. |
| Shallow over rock | Works, with one condition | Radish will crop on shallow over rock, but one thing has to be dealt with first. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering.Water and mulch will carry it through. On this soil the watering is not optional in a dry spell, which is the difference between a crop and a failure. |
| Made ground and urban soil | Works, with one condition | Radish will crop on made ground and urban soil, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse. |
Not sure which you have? Four hand tests will settle it.
Space and spacing
- Mature height
- 15–20 cm
- Mature spread
- 10 cm
- Rooting depth
- 15–20 cm
- Spacing
- 2.5–5 cm apart
- Row spacing
- 15 cm
Where these figures come from
- Mature heightHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Mature spreadHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Rooting depthHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- SpacingSourced guidancehigh confidence
- Royal Horticultural Society: Radishes — spacing
Checked 2026-08-13
- Row spacingSourced guidancehigh confidence
- Royal Horticultural Society: Radishes — spacing
Checked 2026-08-13
In a container
- Minimum volume
- 5 litres or more
- Minimum depth
- 15 cm
Where the container figures come from
- Minimum volumeHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Minimum depthSourced guidancehigh confidence
- Royal Horticultural Society: Radishes in containers
Checked 2026-08-13
The shallowest rooting of any crop in this catalogue, which is why a windowsill trough works.
Where and how you can grow it
Each way of growing is assessed separately, and “not assessed” is a real answer rather than a gap we have filled in with a guess.
| Method | Suitability | What it needs |
|---|---|---|
| Open ground | Well suitedsourceSourced guidancehigh confidence
Checked 2026-08-13 | |
| Raised bed | Well suitedsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | Ideal for filling gaps between slower crops. |
| Traditional dug bed | Well suitedsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | |
| Container | Well suitedsourceSourced guidancehigh confidence
Checked 2026-08-13 | 15 cm of depth is enough |
| Polytunnel | Well suitedsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | For very early and very late sowings. |
| Windowsill | WorkablesourceHorticultural consensusmoderate confidence One of the very few root crops that will produce a real harvest on a sill, given a bright one. No external citation — see the evidence type above. Checked 2026-08-13 | A bright sill; A trough at least 15 cm deep |
| Greenhouse | WorkablesourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | |
| Hydroponics | WorkableSourced guidancelow confidence
Checked 2026-08-13 |
Growing it
- SowingSow thinly, 1–2 cm deep, and keep sowing a short row every fortnight. Radishes do not hold in the ground, so a single large sowing means a glut followed by nothing.1–2 cm
- WateringKeep them growing fast and evenly moist. A check to growth is what makes radishes hot and woody, and it cannot be undone afterwards.
- HarvestingPull as soon as they are big enough. A radish left an extra fortnight is not a bigger radish, it is a worse one.
- FeedingRadishes need no feeding and resent it. On rich or freshly manured ground they make large leaves and hot, hollow, split roots. Sow them on ground used for something else the year before, keep them watered, and pull them young.
Where this guidance comes from
- SowingSourced guidancehigh confidence
- Royal Horticultural Society: Radishes — sowing
Checked 2026-08-13
- WateringSourced guidancehigh confidence
- Royal Horticultural Society: Radishes — watering
Checked 2026-08-13
- HarvestingHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- FeedingSourced guidancemoderate confidence
- Royal Horticultural Society: Radishes — cultivation
Checked 2026-08-13
Is it worth putting under cover?
Whether it will grow there is on the methods table above. This is whether the space is well spent, which is a different question and usually the one being asked.
| Structure | What protection is worth | What decides it |
|---|---|---|
| Greenhouse | Extends the seasonsourceGrowingHQ editorial positionmoderate confidence What protection is worth for this crop, judged against the same standard as every other record in this file.
Checked 2026-08-13 | Speed. A radish is ready in a month, which makes it the one crop that can occupy protected ground without really costing anything. |
| Polytunnel | Extends the seasonsourceGrowingHQ editorial positionmoderate confidence What protection is worth for this crop, judged against the same standard as every other record in this file.
Checked 2026-08-13 | Speed. |
Growing it without soil
Nearly anything can be grown in a soilless system by somebody with enough equipment. The useful question is whether it is worth it, in which technique, and what goes wrong.
Succeeds when the conditions listed here are met and fails when they are not. The conditions are the answer, not a caveat.
Sourced guidancelow confidence
- University of Minnesota Extension — University of Minnesota: Root crops in soilless culture
Checked 2026-08-13
The only root crop here that is worth attempting in a soilless system, and even then a deep tray of compost does the job as well for less equipment.
Techniques that suit it
- Ebb and flowA bed of inert medium floods and drains on a timer. The medium holds moisture between floods, which makes it far more tolerant of interruption than NFT.
- Drip-fed mediumSolution is dripped into an inert medium around each plant. The most forgiving technique and the one that suits large, long-season, heavy crops.
Horticultural consensusDepends on conditionsmoderate confidence
Applies when: Medium-based systems only. A swelling root needs something to swell into.
No external citation — see the evidence type above.
Checked 2026-08-13
- Root space
- Shallow but solid: radish is the one root crop small enough for a medium bed to accommodate properly.
- Lighting
- Needs supplementary light
- pH band
- 5.5–6.5
Where these figures come from
- Root spaceHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- LightingHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- pH bandSourced guidancehigh confidence
Outside roughly this band, individual nutrients become unavailable even when they are present in the solution — which is why a crop can starve in a full reservoir.
- Purdue Extension — Purdue University: Hydroponic solution management — pH
Checked 2026-08-13
What actually goes wrong
- All top and no root, which follows from too much nitrogen or too little light — the commonest outcome of growing radish indoors.
source
Sourced guidancemoderate confidence
- Royal Horticultural Society: Growing radishes
Checked 2026-08-13
No nutrient recipes here
GrowingHQ records pH bands, which are measurable properties of nutrient availability, and deliberately records no EC or PPM targets and no mixing instructions. Published targets vary by cultivar, growth stage, water source and technique, and the figures that apply to your system are on the product you bought.
Harvesting
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Radishes — timing
Checked 2026-08-13
- When it is readyReady when the shoulders are about 2 cm across and just showing at soil level, four to six weeks from sowing.
- How to pick itPull by hand.
- Keeping itA week or so in a refrigerator. Not a storage crop.
Where the harvest guidance comes from
- When it is readySourced guidancehigh confidence
- Royal Horticultural Society: Radishes — harvesting
Checked 2026-08-13
- How to pick itHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Keeping itHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
What goes wrong
| Problem | How often | Notes |
|---|---|---|
| Cabbage root fly | commonsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | The maggots tunnel the part you were going to eat, so damage is found at harvest. |
| Flea beetle | commonsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | |
| Bolting | commonsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | In hot weather and long days, particularly midsummer sowings. |
| Slugs and snails | occasionalsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | |
| Clubroot | occasionalsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | Radishes are brassicas, which growers routinely forget when planning a rotation — they belong in the brassica group. |
Start from what you can see
Grown with, grown after, grown instead
Every relationship states its mechanism. A pairing nobody can explain is a pairing nobody has checked, and it does not go in.
- Same rotation groupCabbageRadish is a brassica and hosts clubroot, so it belongs in the brassica rotation group despite being grown as a root crop and despite occupying the ground for only a month.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Crop rotation
Checked 2026-08-13
- Follows on fromLettuceRadishes clear the ground in four to six weeks, which fits neatly before or between slower salad crops in the same bed.
source
Horticultural consensusmoderate confidence
- Royal Horticultural Society: Intercropping and catch cropping
Checked 2026-08-13
Safety and edibility
- Which parts are edibleThe root, the young leaves and the green seed pods are all edible. The pods of a bolted radish are a crop in their own right and are worth picking rather than discarding the plant.
source
Horticultural consensusmoderate confidence
- Royal Horticultural Society: Radishes
Checked 2026-08-13
Pick the pods from bolted plants while they are still green and crisp.
Sources for this page
Home and Garden Information Center · OSU Extension Service · Royal Horticultural Society · University of Minnesota Extension
Each figure on this page carries its own citation, under the “where these figures come from” note in its section. Record last reviewed 2026-08-13.
If something is wrong with it
- Plant running up to flower before it is ready to eat — 2 causes GrowingHQ holds for radish
Something else? Work through it with the diagnostic tool.