Yes — Strong Match
marigold is grown as an annual, so season length decides it here, not a winter zone — and Delaware's typical season runs ~241 frost-free days against the ~60 marigold needs.
Sow by about Sep 9
Marigold is grown as an annual, so what decides it here is season length, not a winter zone. It needs about 60 frost-free days and a typical Delaware season runs ~241 frost-free days, leaving 181 days of slack. That is room to sow as late as about Sep 9 and still finish before the usual first freeze (Nov 18), or to run a second succession.
Want more weeks at either end of that window? How to buy the weeks →
60 frost-free days required against Delaware’s ~241-day season. NOAA Regional Climate Centers ACIS 1991-2020 (28°F killing freeze), state median across counties, via stateClimateData.ts.
Your yard isn't the whole zone.
Marigold is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Delaware site runs ~241 frost-free days, but that is a state median, not your yard: slope, trees, and low spots move the last-frost date across a single parcel. Enter your address and we'll score marigold against your land's actual frost dates, sun, and soil.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Zone Comparison
Marigold Needs
- USDA Zones: Data pending
- Frost-Free Days: 60+
- Sun: Full Sun
- Mature size: 3 ft tall
- Picking window: ~90 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
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Marigold 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.
When to start the seed
Those dates are when marigold goes out, not when it starts. It is sown under cover about 6 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 70 days to maturity (USDA PLANTS Database), counting from the last hard freeze it ripens with 169 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: USDA PLANTS Database. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
Frost-free days
Marigold wants 60+ frost-free days; a typical Delaware site sees ~241 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Marigold needs ~1700 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
Marigold likes near-neutral soil (pH 6-7.5). 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 and 7 — 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.
Your land, not the state average
Delaware's soils run mostly sandy loam, but SSURGO maps the series, texture, and drainage under your exact parcel. What matters for marigold is the horizon its roots actually work, not the surface. That map unit, not the state average, decides how marigold performs.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. Delaware soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Marigold in Delaware — Quick Answer
- Verdict: Yes — Strong Match
- Plant Zones: Data pending (USDA PLANTS Database)
- State Zones: 7a-8a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Mar 23 - Mar 23 to Nov 17 - Nov 19 (NOAA Regional Climate Centers ACIS, 1991-2020)
- Days to Maturity: 70 days
What Else to Consider for Marigold 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
Growing marigold here specifically
Delaware's soils run mostly sandy loam (Ultisols), and whether that suits marigold's pH 6.0–7.5 preference comes down to your exact parcel, not the statewide picture.
Pull your parcel's SSURGO map unit, test pH, and amend toward marigold's 6.0–7.5 target before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Delaware grower, not just marigold — is covered on the Delaware growing guide.
Timing shifts within Delaware
Marigold needs about 60 days of frost-free season to complete its cycle. Even Sussex County — Delaware’s shortest season at 238 frost-free days — clears that by 178 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"). Marigold's 60-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Marigold draws honeybees, native bees, and butterflies (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, marigold 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.
Good to Know Before You Plant Marigold
On Growable Ground, Marigold means Tagetes erecta — not to be confused with pot marigold (Calendula officinalis). a different genus grown as an edible and medicinal flower — the garden marigold here is Tagetes.
Recommended Marigold Varieties for Delaware
Delaware publishes no state variety trial for marigold, so we won't invent a "best for Delaware" list. Choose types rated to your USDA hardiness zone (7a-8a), and confirm winter survival and drainage against your own parcel.
Delaware Cooperative Extension
For Delaware-specific cultivar recommendations, planting calendars, and pest pressure for marigold, 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 Marigold native to Delaware?
No — the USDA PLANTS Database lists Marigold as introduced rather than native in the Lower 48, so it is not part of Delaware's native flora. It grows here as a garden plant; pairing it with a few Delaware natives keeps local pollinators fed too.
Looking for plants that belong here? The Delaware growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
What pests threaten marigold in Delaware?
Japanese beetle is documented in Delaware and will find marigold, but it is manageable here. What an experienced grower watches for, and does:
Japanese beetle
Worth watchingThis is on the University of Minnesota's list of Japanese beetle preferred plants — but their read is that fruits, vegetables and herbs tolerate limited leaf feeding, and that in most cases the damage is cosmetic and will not kill the plant.
What to do: Protect it only through the few peak weeks: handpick into soapy water in the cool of morning, harvest regularly through July and August to take the feeding pressure off the edible parts, and keep the plant well watered — a vigorous plant outgrows feeding that looks worse than it is. Do not hang a beetle trap.
Documented range: states listed as Japanese-beetle infested · University of Minnesota Extension, National Plant Board
Only pests whose documented range and host relationship both trace to a primary source appear here — so a quiet section means we have nothing sourced to tell you, not that your garden is pest-free.
Common Questions About Growing Marigold in Delaware
When can I plant Marigold 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). Time outdoor planting to after the last hard freeze for your specific site — a further two to three weeks for anything tender — and count back from those dates for transplant scheduling.
Can Marigold mature before first frost in Delaware?
Yes — Marigold matures in 70 days (USDA PLANTS Database), and Delaware's dependable hard-freeze-free window runs 239 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 169 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 Marigold grown in across Delaware?
Delaware spans USDA hardiness zones 7a-8a (USDA ARS PHZM 2023). Marigold carries a range of zones Data pending, 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). Marigold needs 60+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Marigold native to Delaware?
No — the USDA PLANTS Database lists Marigold as introduced rather than native in the Lower 48, so it is not part of Delaware's native flora. It grows here as a garden plant; pairing it with a few Delaware natives keeps local pollinators fed too.
How should I amend the soil for Marigold in Delaware?
Marigold prefers pH 6-7.5 and well (dry spells) drainage (Growable Ground Plant Database). 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 Marigold actually grow on my specific land in Delaware?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores marigold 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 marigold against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Delaware marigold 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 marigold average
Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →
Cite this dataset
Kirchick, M. (2026). Growable Ground Plant Database [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21435643
Licensed CC BY-NC 4.0. DOI 10.5281/zenodo.21435643
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