Delaware planting calendar

When to plant collard greens in Delaware — sow, transplant & harvest dates

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

Collard Greens planting timetable for Delaware

Stage	When in Delaware	Anchor
Start seeds indoors	mid-March (March 18)	4 weeks before the last frost (mid-April)
Transplant outside	late March (March 25)	21 days before the last frost (mid-April)
First harvest (estimate)	early June (June 3)	~70 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 Delaware's climate shifts the collard greens dates

Delaware's last spring frost averages mid-April and first fall frost late October, which sets the whole planting clock. Delaware is small and mild, moderated by the Atlantic and Delaware Bay, with a long, productive mid-Atlantic season. Sow early — collard greens bolt once daytime temperatures hold above 24 °C, so the earlier they go in, the longer the harvest.

Collards are one of the hardiest brassicas, tolerating temperatures down to about -7 °C once established, and one of the most heat-tolerant — unlike kale or cabbage, they continue producing in summer heat above 32 °C, which is why they are a staple in Zones 7–9 year-round. Transplant 2–4 weeks before last spring frost, or direct-sow where the season allows; for a fall harvest, start transplants 8–10 weeks before first fall frost. Succession-plant for continuous leaf harvest.

Frost-risk note

Don't plant before mid-April — a hard freeze can still set young plants back. In the northern Piedmont near Wilmington (zone 7a) the safe date runs a week or two later.

Regional variation within Delaware

the northern Piedmont near Wilmington (zone 7a) runs roughly 1-2 weeks behind the state average; the Atlantic coast and lower Delmarva (zone 8a) can plant 1-2 weeks earlier.

Wilmington — USDA zone 7b
Dover — USDA zone 7b
Newark — USDA zone 7b
Rehoboth Beach — USDA zone 8a

What else to plant in Delaware 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: 18-24 inches (45-60 cm) between plants.
Days to harvest: ~70 days from planting out.

Frequently asked questions

When is the best time to plant collard greens in Delaware?

In Delaware (mostly USDA zone 7b), sow collard greens indoors around mid-March, transplant outdoors late March (before the last frost, mid-April), and harvest from early June. Collard Greens are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

What USDA zone is Delaware?

Most of Delaware sits in USDA hardiness zone 7b, with the state spanning roughly 7a-8a from the northern Piedmont near Wilmington (zone 7a) to the Atlantic coast and lower Delmarva (zone 8a). The last spring frost averages mid-April and the first fall frost late October.

Can you grow collard greens in Delaware?

Yes. Delaware's dominant zone 7b supports collard greens — the key is timing. Collard Greens are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

Does the planting date change across Delaware?

the northern Piedmont near Wilmington (zone 7a) runs roughly 1-2 weeks behind the state average; the Atlantic coast and lower Delmarva (zone 8a) can plant 1-2 weeks earlier.

What else can I plant in Delaware 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.