How to Grow Radishes: Planting, Spacing, Care & Harvest

Quick answer

Sow as soon as soil can be worked in spring, about 2 to 6 weeks before last frost depending on source. Fall: about 4 to 8 weeks before first frost (Purdue). Thin garden radishes to about 2 inches; daikon 4 to 6 inches (UMN). Days: UMD 25 to 35; Clemson 25 to 30.

Bunches of red radishes with greens (Raphanus sativus)
Jeffery Martin, CC0, via Wikimedia Commons · source · license

Radishes at a glance

PlantDirect sow: 5–2 wk before last frost; Fall sow: 6–4 wk before last frost
SunUMD full sun ≥6 hours (prefers 8–10).
WaterUMD evenly moist not wet.
SpacingUMD: seeds 1–2 inches apart in-row, ¼–½ inch deep (or equidistant in wide beds); thin to 2 to 4 inches by type.
Days to harvest25-30
-7-6-5-4-3-2-1LF+1+2+3
■ Start indoors   ■ Plant out   ■ Harvest
Weeks relative to last frost (LF). Colored weeks show when our ZIP planner schedules each step.
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Planting dates for your ZIP: the ZIP planting planner counts each window from your local frost dates.

Organic pests and diseases: see also organic pest control. Use any product as the label directs.

Daikon and winter types stay on this page as sections — same species, not separate thin URLs. Fast-germinating radishes also mark slow rows of carrots or beets (UMD).

Bunches of red radishes with greens
Radish bunches. Photo: Jeffery Martin, Wikimedia Commons, CC0 (resized).

Planting timing

UMD: hardy annual; withstands heavy frosts spring and fall. “Sow seed as soon as the soil can be worked in the spring.” Also fall. Succession: “Plant a small number of seeds every five days.” Hot weather → spicy woody roots. (UMD Extension) Purdue HO-186: hardy — plant 4–6 weeks before last spring frost; fall cool-season table at least 4–8 weeks before first fall frost. (Purdue Extension) UNH: Direct seed 2–4 weeks before last frost. CSU: hardy — as early as 2–4 weeks before average last spring frost; ~30 days to harvest. UMN: spring early April through early May; fall August 1 through September 1 (Minnesota calendar examples). (UMN Extension)

Depth and spacing

UMD: seeds 1–2 inches apart in-row, ¼–½ inch deep (or equidistant in wide beds); thin to 2 to 4 inches by type. UMN: about one inch between seeds; small types ¼–½ inch deep; larger types up to 1 inch; thin garden radishes to ~2 inches; daikon 4 to 6 inches. Loosen soil ≥6 inches (a foot+ for long types); raised beds help daikon. CSU: spacing 2–3 inches; depth ½ inch.

Daikon and winter types

Same species (Raphanus sativus); daikon often treated as var. longipinnatus (UMN). Need deeper, looser soil and wider thinning (4 to 6 inches). UMN: shoulders show width; fork underneath to avoid breakage; store up to ~two months fresh. Raised beds help long roots.

Sun, soil and water

Sun: UMD full sun ≥6 hours (prefers 8–10). Soil: UMD fertile, loose, well-drained. UMN well-drained, pH 6 to 7, not compacted; compost/well-rotted manure; fresh manure N can branch roots; no “Weed and Feed.” Water: UMD evenly moist not wet. UMN about one inch per week; drought → poor flavor and tough texture; uneven moisture → cracking. Marker crop: UMD radishes germinate fast — sprinkle in slow rows (carrots, beets, lettuce, kohlrabi) to mark the row.

Care

Fertilizer: UMD low nutrient need; avoid excess N (tops over roots). Weeds: UMN garden radishes usually outpace weeds; mulch/cultivate carefully for daikon; shallow tools only. Heat: slow growth → overly hot taste (UMN); pithy/hot when overmature or hot weather (UMD).

Harvest and storage

Days: UMD 25–35. Clemson planning chart 25–30. (Clemson HGIC) UMN garden radishes ready three to five weeks after planting. UMD: harvest spring radishes ~one inch diameter before cracking/pith/hot; cut taproot and stem; foliage and seedpods edible (cabbage family). UMN: pull at usable size; remove greens; wash; fridge only a week or two. Yield (UMD): about 3 lbs per 10-foot row. Storage: UMD wash/dry; plastic bags; 32–40°F, 95% RH, 1 to 2 weeks.

Pests and diseases (organic)

Flea beetles: UMN: small round holes; worst on young spring seedlings. Cultural: floating row cover from seeding.

Cabbage maggot: UMN radish page: cabbage maggots tunnel roots. Root-maggots guide: row covers before early–mid May flight; rotate; avoid covering last year’s brassica ground; no spring manure that attracts flies. (UMN root maggots)

Wireworms: UMN: burrow tunnels — cultural (avoid planting into grassy sod when possible).

Diseases: UMN Alternaria leaf spots; black rot (yellow triangles); clubroot (stunted roots). Rotation and drainage; same brassica-family hygiene as cole crops.

Related: how to grow carrots · how to grow beets · cabbage-family companions · organic pest control · ZIP planner

Frequently asked questions

When do I plant radishes?

Spring: as soon as soil works / about 2–6 weeks before last frost depending on source. Fall: about 4–8 weeks before first frost (Purdue)

Why are my radishes all tops / spicy?

Crowding (UMN), excess nitrogen (UMD), heat or slow growth (UMN/UMD), or left too long.

How do I stop maggots in the roots?

Row cover before flies lay eggs; rotate off last year’s brassicas; skip spring manure on that bed (UMN).

More grow guides: Asparagus · Peas · Cauliflower · Rhubarb · Leeks · Parsley · Swiss chard · Eggplant · Arugula · Cilantro · All grow guides

Sources