Washington, DC planting calendar

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

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

Zucchini planting timetable for Washington, DC

Stage	When in Washington, DC	Anchor
Start seeds indoors	late March (March 25)	3 weeks before the last frost (mid-April)
Transplant outside	late April (April 29)	14 days after the last frost (mid-April)
First harvest (estimate)	late June (June 23)	~55 days from transplant

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 zucchini 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. Wait for warm soil — zucchini stall in cold ground even after the air warms, so don't rush them out.

Zucchini is the fastest-maturing summer squash — soil must reach 18 °C (65 °F) before sowing or transplanting, as cold soil causes slow, weak germination and root rot. One or two plants per family member is usually sufficient; succession-sowing every 3-4 weeks extends harvest but rarely necessary given prolific production. Harvest fruit at 15-20 cm (6-8 inches) every 2-3 days to maintain plant productivity; leaving fruits to overgrow reduces total yield.

Frost-risk note

Don't plant before mid-April — even a light frost will kill seedlings overnight. 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

Pair the post-frost slot with other warm-season crops — peppers, beans, squash, and cucumbers.

Quick-grow guide

Sun: Full sun — 6-8 hours direct.
Soil temperature for germination: 21-29 °C (70-85 °F).
Spacing: 24-36 inches (60-90 cm) between plants.
Days to harvest: ~55 days from planting out.

Frequently asked questions

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

In Washington, DC (mostly USDA zone 8a), sow zucchini indoors around late March, transplant outdoors late April (after the last frost, mid-April), and harvest from late June. Zucchini are frost-tender — a single light frost kills seedlings, so they only go outside once frost danger has fully passed and the soil is warm.

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 zucchini in Washington, DC?

Yes. Washington, DC's dominant zone 8a supports zucchini — the key is timing. Zucchini are frost-tender — a single light frost kills seedlings, so they only go outside once frost danger has fully passed and the soil is warm.

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?

Pair the post-frost slot with other warm-season crops — peppers, beans, squash, and cucumbers.

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.