How to Grow Radishes
Raphanus sativus
By Efraín Vega · Published October 10, 2026
Sun
Full sun: at least 6 hrs of direct light, ideally 8–10
Water
Evenly moist but not wet
Spacing
Sow 1–2 in apart; thin to 2–4 in; rows 12–24 in apart
Soil pH
6.2–6.5
Days to maturity
25–35 days from seed (some varieties 21–30)
Hardiness zones
Cool-season annual in all US zones
When to plant: As soon as the soil can be worked in spring, and again in early fall
Radishes are the fastest crop in the garden: most are ready 25–35 days after sowing. Plant them in cool weather, thin seedlings to 2–4 inches apart, keep the soil evenly moist, and pull round red types when they're about 1 inch across.
Because they're so quick, radishes fit into gaps between slower crops in a raised bed.
When should you plant radishes?
In cool weather. University of Maryland Extension recommends sowing as soon as the soil can be worked in spring, and again in fall. Radishes planted late in spring run into heat and bolt, which makes them pithy and strong-flavored, according to Clemson Extension.
For a steady supply, sow a small batch every five days instead of one big planting.
How far apart should you plant radishes?
Sow seeds 1–2 inches apart, ¼–½ inch deep. When they sprout, thin to 2–4 inches apart depending on the variety. Rows can be 12–24 inches apart, or sow in a wide band across a raised bed.
Thin early
Crowded radishes grow tops but no roots. Thin as soon as seedlings are up — snipping extras at soil level avoids disturbing the ones you keep.
What makes radishes woody or hot?
- Heat: Clemson Extension notes high temperatures make radishes crack, turn pithy and develop a strong flavor.
- Dry soil: moisture stress while roots form makes them woody. Keep the soil evenly moist but not wet.
- Waiting too long: radishes go from crisp to spongy fast.
When do you harvest radishes?
Pull round red radishes when they're about 1 inch in diameter, before they crack or turn pithy. Clemson recommends harvesting white types a little smaller, around ¾ inch. Check a few every couple of days once they're close.
Starting a quick-crop bed? The Raised Bed Soil Calculator tells you how much soil mix to buy.
Sources: Growing Radishes in a Home Garden — UMD Extension, Carrot, Beet, Radish & Parsnip — Clemson HGIC, Target Soil pH Values for Vegetable Crops — UMD Extension.
Companion plants
Lettuce, Spinach, Carrots
FAQ
Why are my radishes woody or too spicy?
Heat, dry soil or leaving them in the ground too long. Radishes turn hot and woody as temperatures rise or once they're past maturity, so grow them in cool weather, keep the soil evenly moist, and harvest promptly.
Why did my radishes grow leaves but no roots?
Usually crowding. Thin seedlings to 2–4 inches apart soon after they come up — roots can't swell when plants are packed together.
How often should I plant radishes?
University of Maryland Extension suggests sowing a small batch every five days for several plantings, so you pick a few at a time instead of all at once.
How much sun do radishes need?
Full sun: at least 6 hours of direct light, ideally 8–10.
How often should you water radishes?
Keep the soil evenly moist but not wet. Uneven watering is one cause of woody, extra-spicy roots.
