Washington, DC planting calendar

When to plant radishes in Washington, DC — sow, transplant & harvest dates

Washington, DC is mostly USDA zone 8a (range 7b-8a). Dates below are derived from radishes's frost tolerance and Washington, DC's frost window — not generic national averages.

Radishes planting timetable for Washington, DC

Stage	When in Washington, DC	Anchor
Direct-sow outside	late March (March 25)	21 days before the last frost (mid-April)
First harvest (estimate)	late April (April 22)	~28 days from direct sow

Dates are state-wide averages for the dominant zone. Local microclimates — elevation, urban heat, coastal moderation — can shift the window by 1-2 weeks. Use the frost-date calculator for a date tuned to your town.

Why Washington, DC's climate shifts the radishes dates

Washington, DC's last spring frost averages mid-April and first fall frost late October, which sets the whole planting clock. Washington, DC sits in a warm mid-Atlantic pocket where the urban heat island pushes much of the city into zone 8a — warmer than the surrounding suburbs. Sow early — radishes bolt once daytime temperatures hold above 24 °C, so the earlier they go in, the longer the harvest.

Radishes are the fastest root crop — spring types mature in 22-30 days from direct sowing, making them ideal row-markers alongside slower crops. Sow 2-4 weeks before the last spring frost as soon as soil can be worked; they bolt and become pithy and peppery hot if left too long in warming soil. Succession-sow every 7-10 days for a continuous harvest; daikon and winter types sown in late summer take 50-70 days and tolerate heavier frost.

Frost-risk note

Don't plant before mid-April — a hard freeze can still set young plants back. In outer neighborhoods away from the urban core (zone 7b) the safe date runs a week or two later.

Regional variation within Washington, DC

outer neighborhoods away from the urban core (zone 7b) runs roughly 1-2 weeks behind the state average; the dense urban core, lifted by the city heat-island (zone 8a) can plant 1-2 weeks earlier.

Downtown DC — USDA zone 8a
Georgetown — USDA zone 8a
Anacostia — USDA zone 7b

What else to plant in Washington, DC around then

The same early window suits peas, lettuce, spinach, and onion sets.

Quick-grow guide

Sun: Full sun — 6+ hours direct.
Soil temperature for germination: 7-29 °C (45-85 °F).
Spacing: 2-3 inches (5-8 cm) between plants.
Days to harvest: ~28 days from planting out.

Frequently asked questions

When is the best time to plant radishes in Washington, DC?

In Washington, DC (mostly USDA zone 8a), direct-sow radishes late March (before the last frost, mid-April), and harvest from late April. Radishes are half-hardy — young plants shrug off a light frost but not a hard freeze, so sowing can start a couple of weeks before the last spring frost.

What USDA zone is Washington, DC?

Most of Washington, DC sits in USDA hardiness zone 8a, with the state spanning roughly 7b-8a from outer neighborhoods away from the urban core (zone 7b) to the dense urban core, lifted by the city heat-island (zone 8a). The last spring frost averages mid-April and the first fall frost late October.

Can you grow radishes in Washington, DC?

Yes. Washington, DC's dominant zone 8a supports radishes — the key is timing. Radishes are half-hardy — young plants shrug off a light frost but not a hard freeze, so sowing can start a couple of weeks before the last spring frost.

Does the planting date change across Washington, DC?

outer neighborhoods away from the urban core (zone 7b) runs roughly 1-2 weeks behind the state average; the dense urban core, lifted by the city heat-island (zone 8a) can plant 1-2 weeks earlier.

What else can I plant in Washington, DC around the same time?

The same early window suits peas, lettuce, spinach, and onion sets.

Source and methodology

State zone spans from the USDA Plant Hardiness Zone Map (2023); frost-date averages from NOAA Climate Data Online. Hot-state two-season timing cross-checked against the UF/IFAS Florida Gardening Calendar and the University of Arizona Cooperative Extension planting calendar. Curated by the Growli editorial team.