Millsboro, Delaware, sits in USDA hardiness zone 7b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
On paper, cabbage, prickly pear, california poppy, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Even in Millsboro, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Millsboro lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Millsboro — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Millsboro — the short answer
Millsboro, Delaware: USDA zone 7b, about 238 days between hard freezes, across 3K acres of town.
- USDA zone
- 7b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 23
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 16
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~238
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 3K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 7b is Millsboro's average, not your lot's — a low corner or a tree line moves it. Against Millsboro's 238-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Millsboro
Each reading below is measured for Millsboro itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredMillsboro runs about 238 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredMillsboro sits in USDA hardiness zone 7b.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Millsboro is in
Millsboro sits in the Middle Atlantic Coastal Plain — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Millsboro's own centroid rather than borrowed from Sussex County.
What Grows in Millsboro
Every plant below cleared Millsboro's own zone 7b and its 238-day season. Each card opens that plant's Delaware profile. How we score.
Is it too late to plant in Millsboro?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Feb 23; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 23 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 16 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
Documented around Millsboro
Spotted lanternfly documented 4 miles from Millsboro, first recorded 2022. What to watch for.
What's on the federal record near Millsboro
Closest first, within ~10 miles of Millsboro. Listing isn't leaking, and distance isn't exposure.
- Whaley PropertyUnderground Storage Tanks · 1500 ft
- Frank Smith NurseryUnderground Storage Tanks · 2000 ft
- Sterwin LaboratoriesUnderground Storage Tanks · 2100 ft
- Intervet IncUnderground Storage Tanks · 2100 ft
- INTERVET, INC. (DBA MERCK ANIMAL HEALTH)Brownfields · 2100 ft
- Millsboro FordUnderground Storage Tanks · 0.5 mi
- Simmons Cable TVUnderground Storage Tanks · 0.6 mi
- MILLSBORO TCESuperfund · 0.6 mi
- Walla PropertyUnderground Storage Tanks · 0.7 mi
- Gulabs Tire CenterUnderground Storage Tanks · 0.8 mi
- Millsboro MobilUnderground Storage Tanks · 0.8 mi
- Lakeview FarmsUnderground Storage Tanks · 0.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Millsboro's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Millsboro.
Sources Checked
within ~10 miles of Millsboro
Severity Distribution
within ~10 miles of Millsboro
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Millsboro, Nitrate runs higher than the national average — 378 sites within ~10 miles of Millsboro. That's not a problem with your land — it's information about it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Millsboro
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Millsboro average
Your land is one point inside Millsboro
Everything above resolves to Millsboro as a whole — one PHZM band and one 28°F frost record, read across 3K acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at town scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the Millsboro Average
Millsboro Average
- ●USDA Zones 7b, averaged across Millsboro
- ●One soil character for all of Millsboro
- ●Frost dates read at Millsboro's scale: Mar 23 to Nov 16
YOUR Parcel
- ✓Your exact zone, not Millsboro's 7b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Millsboro
Pull a site-specific report for your exact address in Millsboro, Delaware — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Millsboro averages can't show:
We read public map data around Millsboro — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Millsboro average
How we know this about Millsboro
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Millsboro’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Millsboro
When does frost risk typically end in Millsboro?
The last hard freeze (28°F) in Millsboro typically lands around Mar 23, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Apr 13.
When is the first frost in Millsboro?
The first hard freeze (28°F) in Millsboro typically arrives around Nov 16, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 2, so the watching starts about Oct 17 — about 238 days after the spring freeze cleared.
How long is the growing season in Millsboro?
Measured between 28°F hard freezes, Millsboro sees about 238 frost-free days — roughly Mar 23 through Nov 16, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 13 to Nov 2, about 203 days.
Is the soil safe to grow vegetables in Millsboro?
The federal record around Millsboro runs heavier than most — 707 documented sites, mostly Nitrate entries (378), the nearest Underground Storage Tanks record about 0.3 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do I protect my plants from frost in Millsboro?
From about Oct 17 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Nov 16 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Nov 16. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Millsboro's scale — its 7b band and its 238-day season. Your yard writes its own version of Millsboro's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Millsboro’s own scale
7 of the readings below were taken at Millsboro's own scale — its own ~238-day season between 28°F freezes, the 3,284 acres it covers and 707 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Millsboro's own USDA hardiness band, zones 7bUSDA PHZM 2023
- Millsboro's own 28°F hard-freeze dates, about Mar 23 and Nov 16 and the ~238-day span between themNOAA 1991–2020 Climate Normals
- 707 documented contamination sites on the federal record near Millsboro, the closest Underground Storage Tanks record about 0.3 miles out from the town centreFederal environmental registers
- Millsboro's boundary and the 3,284 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7b and a ~238-day seasonGrowable Ground crop-matching engine
- The ecoregion at Millsboro's own centroid, the Middle Atlantic Coastal PlainUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Millsborolydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Millsboro's 3,284 acres read through its county's SSURGO summaryfrom Sussex County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Sussex County
- The growing challenges every Delaware grower plans around — written at state scale, so they stay on the state guidefrom Delaware
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Sussex County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Millsboro's 3,284 acreswhy one lot differs from the next →
- Which side of Millsboro you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 3,284 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.3 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Millsboro-wide figureread your own land →