When to Plant Radishes in Washington, DC
Published: April 24, 2026
Radish Planting Dates for Washington, DC
| Start seeds indoors | Year-round |
| Last frost (average) | March 22 |
| Direct sow outdoors | February 15–25 |
| Minimum soil temperature | 40°F |
| Expect first harvest | March 9 – March 17 |
| Fall crop planting | October 6–16 |
| Fall crop harvest | October 28 |
| First fall frost (average) | November 10 |
⚠Direct sow radishes 4–6 weeks before last frost — one of the fastest crops in the garden. Ready in as little as 22 days. Succession plant every 2 weeks for continuous harvest.
Best Radish Varieties for Washington, DC
Consult a Washington-area nursery or your state extension office for radish varieties proven in Zone 6b.
Growing Radishes in Washington
Washington sits in Zone 6b, with an average last frost of March 22 and first fall frost around November 10 — giving a 233-day frost-free growing season. Cool-season crops like radish benefit from Washington's cooler spring and fall windows, when temperatures stay in the 55–75°F sweet spot that produces the best flavor and least bolting.
Washington's moderate climate supports radish on the standard transplant calendar with minimal special accommodation. Succession planting — sowing fresh seeds or setting new transplants every 2–3 weeks through spring — stretches the harvest window and gives you a backup crop if pests hit the first planting.
Washington's mixed soil conditions vary block by block — get a soil test if you have not in three years. Generally, a base of quality compost (2 to 3 inches annually) and consistent watering at 1 inches per week serves radish well across most soil types found in Washington.
Radish Calendar for Washington
| Month | Task |
|---|---|
| Year | Start seeds indoors under grow lights |
| March | Last frost — soil warming, prepare bed |
| February | Direct sow seeds into warm soil |
| March | Expect first harvest window to open |
| October | Start fall crop — transplants or direct sow |
| November | First fall frost — harvest remaining, end of outdoor season |
Radish Tips for Washington Gardeners
- •Thin to 2-inch spacing when seedlings are an inch tall — crowded radishes produce small woody roots.
- •Succession plant every 10–14 days from early spring through late spring for continuous harvest.
- •Succession plant radish in Washington every 2–3 weeks through spring to extend the harvest window into summer.
Common Radish Pests in Washington
- •Flea Beetle — peaks July in Zone 6b (active May–September); tiny black beetles that riddle leaves with holes; row covers protect seedlings.
- •Cabbage Root Maggot — peaks July in Zone 6b (active May–September); monitor closely during peak season and treat early.
- •Aphid — peaks July in Zone 6b (active May–September); monitor closely during peak season and treat early.
Check plants every 2–3 days during peak season — early intervention prevents most infestations from becoming serious.
What to Plant with Radishes in Washington
In Washington's moderate climate, Lettuce and Carrot are the most beneficial plants to grow alongside radish. Lettuce improves nearby plant health and pest resistance. Keep radish away from Hyssop — it competes for nutrients or shares pest pressure.
Frequently Asked Questions
When should I plant radish in Washington, DC?
In Washington (Zone 6b), direct sow radish around February 15–25. Soil must be at 40°F or warmer at 2-inch depth before sowing — cold soil rots the seeds.
What zone is Washington, DC for radish growing?
Washington is USDA Zone 6b. For radish, this means a frost-free growing season of roughly 33 weeks running from March 22 to November 10. Cool-season crops like radish thrive in this zone with both spring and fall planting windows available.
When is radish harvest season in Washington?
Expect the first radish harvest in Washington around March 9, with harvest continuing through March 17. This is based on 22–30 days from transplant or direct sow. A fall crop planted October 6–16 adds a second harvest around October 28.
How long does it take to grow radish in Washington, DC?
From transplant or direct sow to first harvest, radish takes 22–30 days in Washington's climate. Based on a typical planting date of February 15–25, expect your first harvest around March 9. Washington's Zone 6b transition-zone climate produces maturity times right in the middle of the stated range.
What soil does radish need in Washington?
Washington's soil conditions vary block by block. Before planting radish, do a soil test (most state extension offices run them for $15–30). The test reveals pH, key nutrient levels, and organic matter content, so you can amend appropriately rather than guessing. Generally, 2–3 inches of compost annually improves most soils for vegetable production.