Yes — Strong Match
plains coreopsis is grown in zones 2-11, which covers every zone Connecticut contains (6a-7b). Whether the season is long enough is the question that remains.
Plains Coreopsis in Connecticut — the short answer
Plains Coreopsis in Connecticut: grown in zones 2–11, full sun, against a state median of ~207 frost-free days.
- Plant zones
- Grown as an annual — see the growing season
- Growing season, not a hardiness zone
- Connecticut zones
- 6a-7b
- USDA PHZM 2023
- Frost window
- Mar 31 - Apr 11 – Oct 30 - Nov 3
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 191 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
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.
Plains Coreopsis is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Connecticut site runs ~207 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 plains coreopsis against your land's actual frost dates, sun, and soil.
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Connecticut is not one climate
A single Connecticut answer averages 9 counties whose growing seasons are 48 days apart — from 191 frost-free days in Northwest Hills County to 239 in Greater Bridgeport County. Which end of that your land sits nearer changes what plains coreopsis can finish before the first hard freeze.
The middle half of 9 counties runs 202–216 days, with a median of 207 days — a 48-day span end to end.
Measured across 9 Connecticut counties. NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze. Quartiles are order statistics — every figure shown is a value a real county recorded, not an interpolation. Your own site sits somewhere inside this range; a parcel report resolves where.
Where in Connecticut Fits Best
Even within Connecticut's zones 6a-7b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for plains coreopsis (USDA PHZM 2023):
Zone Comparison
Plains Coreopsis Needs
- USDA Zones: 2-11
- Sun: Full Sun
- Mature size: 3 ft tall
- Picking window: ~60 days of harvestWe haven't confirmed this against a published source yet.
- Drought tolerance: Low
Connecticut Has
- USDA Zones: 6a-7b
- Last Hard Freeze (28°F): Mar 31 - Apr 11
- First Hard Freeze (28°F): Oct 30 - Nov 3
- Annual Rainfall: 44-52 inches
- Common Soils: Glacial till, Sandy loam, River valley silt
Plant Zone Range (zones 2-11)
Preferred Soil pH
We haven't confirmed this against a published source yet.
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 Plains Coreopsis in Connecticut
The frost window
Across Connecticut, the last spring hard freeze (28°F) clears between Mar 31 and Apr 11, and the first fall hard freeze lands between Oct 30 and Nov 3 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 202-day window you can count on — up to 217 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 plains coreopsis goes out, not when it starts. It is sown under cover about 6 weeks ahead, so counting back from Connecticut's late-side last freeze of Apr 11 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
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.
Soil + Drainage Fit
Plains Coreopsis likes near-neutral soil (pH 5.5-7.5). That's the common-ground band across Connecticut's glacial till and sandy 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 Connecticut soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Connecticut site is heavier clay or sits in a low spot, a raised bed lifts the roots above wet ground, or work in compost. pH range and preferred pH: We haven't confirmed this against a published source yet.
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. Connecticut soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Plains Coreopsis in Connecticut
The zone range tells you where plains coreopsis is grown — but Connecticut growers also need to think about:
Rocky glacial soils require clearing and amendment
Short growing season in northern hills
Deer pressure is high in suburban areas
What to actually do about these — and the constraints that apply to every Connecticut grower, not just plains coreopsis — is covered on the Connecticut growing guide.
Where in Connecticut Plains Coreopsis Is Zone-Hardy
Plains Coreopsis is rated for USDA zones 2–11. Every one of Connecticut’s 9 counties sits inside that band — from Northwest Hills County at zone 6a to South Central Connecticut County at zone 7a — so winter cold is not what decides this plant anywhere in the state. What is left to vary is your own parcel: slope, shelter and cold-air drainage routinely move a site half a zone either way from the county figure.
Across those 9 counties Connecticut’s winter-low ladder runs from zone 6a in Northwest Hills County to zone 7a in South Central Connecticut County — 1 USDA zone of spread, which is 10°F between the two counties’ average coldest night of the year. That is why a statewide hardiness answer is where you start and not where you finish.
The planting window moves with it. Northwest Hills County holds its last hard freeze (28°F) until about Apr 19, while Greater Bridgeport County is clear by Mar 27 — 23 days apart. Set plains coreopsis out on your county’s date, not the state’s.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F killing freeze — earlier than the folk 32°F "last frost". Plains Coreopsis’s zone 2–11 band: a season crop, no zone claim. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Plains Coreopsis draws honeybees, native bees, and butterflies (high value). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, plains coreopsis can only work that bloom inside Connecticut's frost window — roughly 207 days, opening after the last 28°F freeze (Mar 31 - Apr 11) and closing at the first (Oct 30 - Nov 3), per NOAA Regional Climate Centers ACIS, 1991-2020. Pollinator value: We haven't confirmed this against a published source yet.
Connecticut Cooperative Extension
For Connecticut-specific cultivar recommendations, planting calendars, and pest pressure for plains coreopsis, the canonical source is UConn Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Plains Coreopsis native to Connecticut?
The USDA PLANTS Database (accessed 2026-10-19) lists Plains Coreopsis as native to the Lower 48 and records it growing in Connecticut, but it does not say whether those Connecticut plants are native or introduced. Your state's native plant society or Cooperative Extension can tell you whether it is part of the local flora.
State records: USDA PLANTS Database state-distribution data (presence, not state-level nativity), accessed 2026-10-19.
Common Questions About Growing Plains Coreopsis in Connecticut
When can I plant Plains Coreopsis in Connecticut?
Connecticut's last spring hard freeze (28°F) clears between Mar 31 and Apr 11, and the first fall hard freeze lands between Oct 30 and Nov 3 (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.
What hardiness zone is Plains Coreopsis grown in across Connecticut?
Connecticut spans USDA hardiness zones 6a-7b (USDA ARS PHZM 2023). Plains Coreopsis carries a range of zones 2-11, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Connecticut site have?
A typical Connecticut site sees ~207 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Plains Coreopsis 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 Plains Coreopsis native to Connecticut?
The USDA PLANTS Database (accessed 2026-10-19) lists Plains Coreopsis as native to the Lower 48 and records it growing in Connecticut, but it does not say whether those Connecticut plants are native or introduced. Your state's native plant society or Cooperative Extension can tell you whether it is part of the local flora.
How should I amend the soil for Plains Coreopsis in Connecticut?
Plains Coreopsis prefers pH 5.5-7.5 and well (dry spells) drainage. We haven't confirmed this against a published source yet. That sits in the common-ground band across Connecticut soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Plains Coreopsis actually grow on my specific land in Connecticut?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores plains coreopsis against your address's mapped soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Connecticut
State-level data is a sketch. Your Growable Ground report scores plains coreopsis against your land's mapped soil, modelled sun, drainage, and frost data — not zone averages.
Three things about your lot that Connecticut plains coreopsis averages can't show:
We read public map data around Connecticut — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Connecticut plains coreopsis average
Explore More
Growing guides for plains coreopsis
Explore Connecticut county by county
Connecticut carries 9 counties with their own USDA zone — a sample of the growing pages for plains coreopsis there:
Where else plains coreopsis grows
Plains Coreopsis's zone band crosses state lines — these are the states closest to Connecticut 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 Connecticut
Connecticut has a growing page for 887 plants — a rotating sample of the rest of the shelf.
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