Generally — Most Areas
black-eyed Susan (zones 3-7) suits most of Delaware (7a-8a) — zone 7 are in range, and the rest of the state is the exception.
Black Eyed Susan in Delaware — the short answer
Black Eyed Susan in Delaware: hardy in zones 3–7, full sun, against a state median of ~241 frost-free days.
- Plant zones
- 3-7
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Delaware zones
- 7a-8a
- USDA PHZM 2023
- Frost window
- Mar 23 - Mar 23 – Nov 17 - Nov 19
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 238 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 120 days
- Growable Ground Plant Database
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — per-field provenance varies and is published with the dataset.
Your yard isn't the whole zone.
Delaware spans zones 7a-8a, but your yard has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score black eyed susan against your land's actual soil, sun, and frost.
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Where Black Eyed Susan Stands in Delaware
Black Eyed Susan is rated for zones 3–7 — a cold floor USDA puts at -40 to -30°F. No Delaware county sits inside it, so in open ground this is a grown-under-cover plant here rather than a bed plant — which is a statement about Delaware winters, not about black eyed susan.
Above the zone 7 ceiling
3 counties
- Kent County · zone 7b
- New Castle County · zone 7b
- Sussex County · zone 7b
Too little winter chill rather than too much cold — a low-chill selection is what changes it.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. A zone is a 10°F band of average annual extreme minimum temperature, so the floor above is the band the plant's rating denotes, not a single measured kill point. Slope, shelter and cold-air drainage routinely move a site half a zone either way from its county figure — which is the part only your address resolves.
Zone Comparison
Black Eyed Susan Needs
- USDA Zones: 3-7
- Sun: Full Sun
- Mature size: 1 ft tall
- Picking window: ~45 days of harvest
- Drought tolerance: Medium
Delaware Has
- USDA Zones: 7a-8a
- Last Hard Freeze (28°F): Mar 23 - Mar 23
- First Hard Freeze (28°F): Nov 17 - Nov 19
- Annual Rainfall: 42-48 inches
- Common Soils: Sandy loam, Silt loam, Tidal marsh
Plant Zone Range (zones 3-7)
Preferred Soil pH
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Black Eyed Susan in Delaware
The frost window
Across Delaware, the last spring hard freeze (28°F) clears between Mar 23 and Mar 23, and the first fall hard freeze lands between Nov 17 and Nov 19 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 239-day window you can count on — up to 241 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
Frost tenderness
Black Eyed Susan is frost-tender — FAO ECOCROP puts its killing temperature at 32°F — so set plants out two to three weeks PAST your local last hard freeze, not on it and not on the state's earliest date. The 28°F marker above is when killing freezes stop, not when light frost does. That is the point where cold damages growing tissue, not a winter-survival floor — an established perennial comes through far colder while dormant, which is what its hardiness zone tells you.
When to start the seed
Those dates are when black eyed susan goes out, not when it starts. It is sown under cover about 8 weeks ahead, so counting back from Delaware's late-side last freeze of Mar 23 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Days to maturity vs. the window
At 120 days to maturity (Growable Ground Plant Database), counting from the last hard freeze it ripens with 119 days to spare even in Delaware's tightest freeze scenario — room for a later start or a second sowing.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
The zone check says black eyed susan survives winter in part of Delaware, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Days to maturity
Black Eyed Susan matures in ~120 days (Growable Ground Plant Database). A typical Delaware site has ~241 frost-free days, so plenty of room for a second succession.
Growing degree days
Black Eyed Susan needs ~1000 GDD (base 50°F) to ripen. The state median runs ~3732 GDD (from PRISM 1991-2020 climate normals), so Delaware's typical season clears that easily.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Soil + Drainage Fit
Black Eyed Susan likes near-neutral soil (pH 5.5-8). That's the common-ground band across Delaware's sandy loam and silt loam — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6.5 and 7.5 — worth knowing before you decide whether a Delaware soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Delaware site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Delaware soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Black Eyed Susan in Delaware
Zone compatibility tells you about winter cold survival — but Delaware growers also need to think about:
Sandy soils in southern DE drain too quickly
Salt spray damage near the coast
Rising water tables in low-lying areas
What to actually do about these — and the constraints that apply to every Delaware grower, not just black eyed susan — is covered on the Delaware growing guide.
Timing shifts within Delaware
Black Eyed Susan needs about 120 days of frost-free season from planting to harvest. Even Sussex County — Delaware’s shortest season at 238 frost-free days — clears that by 118 days, so season length isn’t the constraint anywhere in Delaware. What varies is your own parcel.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). Black Eyed Susan's 120-day requirement: USDA PLANTS / Growable Ground plant database (days to maturity). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Black Eyed Susan draws honeybees, native bees, and butterflies (high value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, black eyed susan can only work that bloom inside Delaware's frost window — roughly 241 days, opening after the last 28°F freeze (Mar 23 - Mar 23) and closing at the first (Nov 17 - Nov 19), per NOAA Regional Climate Centers ACIS, 1991-2020.
Delaware Cooperative Extension
For Delaware-specific cultivar recommendations, planting calendars, and pest pressure for black eyed susan, the canonical source is University of Delaware Cooperative Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Black Eyed Susan native to Delaware?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Black Eyed Susan as native to Delaware. Planting it supports the pollinators and wildlife that evolved alongside it.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Black Eyed Susan in Delaware
When can I plant Black Eyed Susan in Delaware?
Delaware's last spring hard freeze (28°F) clears between Mar 23 and Mar 23, and the first fall hard freeze lands between Nov 17 and Nov 19 (NOAA Regional Climate Centers ACIS, 1991-2020). Black Eyed Susan is frost-tender — its killing temperature is 32°F (FAO ECOCROP — the point where cold damages growing tissue, not a winter-survival floor) — so wait two to three weeks past your site's last hard freeze, when light frost has also stopped, before planting out.
Can Black Eyed Susan mature before first frost in Delaware?
Yes — Black Eyed Susan matures in 120 days (Growable Ground Plant Database), and Delaware's dependable hard-freeze-free window runs 239 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 119 days of margin. Plant once the last hard freeze has passed — two to three weeks later for anything tender — and it ripens ahead of the first fall freeze.
What hardiness zone is Black Eyed Susan grown in across Delaware?
Delaware spans USDA hardiness zones 7a-8a (USDA ARS PHZM 2023). Black Eyed Susan carries a range of zones 3-7, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Delaware site have?
A typical Delaware site sees ~241 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Black Eyed Susan should be matched against that window, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Black Eyed Susan native to Delaware?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Black Eyed Susan as native to Delaware. Planting it supports the pollinators and wildlife that evolved alongside it.
How should I amend the soil for Black Eyed Susan in Delaware?
Black Eyed Susan prefers pH 5.5-8 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Delaware soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Black Eyed Susan actually grow on my specific land in Delaware?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores black eyed susan against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Delaware
State-level data is a sketch. Your Growable Ground report scores black eyed susan against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Delaware black eyed susan averages can't show:
We read public map data around Delaware — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Delaware black eyed susan average
Explore More
Growing guides for black eyed susan
Explore Delaware county by county
Delaware carries 3 counties with their own USDA zone — a sample of the growing pages for black eyed susan there:
Where else black eyed susan grows
Black Eyed Susan's zone band crosses state lines — these are the states closest to Delaware in winter climate where it also has a page, plus the far ends of its range. Each one re-answers the question with that state's own record.
More to grow in Delaware
Delaware has a growing page for 1,013 plants — a rotating sample of the rest of the shelf.
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