Yes — Strong Match
sunflower (zones 2-11) covers every zone Missouri contains (5b-8a), so hardiness is not what limits it anywhere in the state.
Sunflower in Missouri — the short answer
Sunflower in Missouri: hardy in zones 2–11, full sun, against a state median of ~219 frost-free days.
- Plant zones
- 2-11
- 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
- Missouri zones
- 5b-8a
- USDA PHZM 2023
- Frost window
- Mar 27 - Apr 2 – Oct 31 - Nov 7
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 192 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 80 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.
Sunflower is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Missouri site runs ~219 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 sunflower against your land's actual frost dates, sun, and soil.
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Missouri is not one climate
A single Missouri answer averages 115 counties whose growing seasons are 66 days apart — from 192 frost-free days in Crawford County to 258 in Pemiscot County. Which end of that your land sits nearer changes what sunflower can finish before the first hard freeze.
The middle half of 115 counties runs 211–225 days, with a median of 219 days — a 66-day span end to end.
Measured across 115 Missouri 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 Missouri Fits Best
Even within Missouri's zones 5b-8a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for sunflower (USDA PHZM 2023):
Zone Comparison
Sunflower Needs
- USDA Zones: 2-11
- Frost-Free Days: 70+
- Sun: Full Sun
- Mature size: 8 ft tall
- Picking window: ~14 days of harvest
- Drought tolerance: Medium
Missouri Has
- USDA Zones: 5b-8a
- Last Hard Freeze (28°F): Mar 27 - Apr 2
- First Hard Freeze (28°F): Oct 31 - Nov 7
- Annual Rainfall: 34-50 inches
- Common Soils: Silt loam, Clay loam, Loess
Plant Zone Range (zones 2-11)
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 Sunflower in Missouri
The frost window
Across Missouri, the last spring hard freeze (28°F) clears between Mar 27 and Apr 2, and the first fall hard freeze lands between Oct 31 and Nov 7 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 212-day window you can count on — up to 225 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
Sunflower 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 sunflower goes out, not when it starts. It is sown under cover about 3 weeks ahead, so counting back from Missouri's late-side last freeze of Apr 2 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 80 days to maturity (Growable Ground Plant Database), counting from the last hard freeze it ripens with 132 days to spare even in Missouri'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 sunflower survives winter here. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Sunflower wants 70+ frost-free days; a typical Missouri site sees ~219 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Sunflower needs ~1500 GDD (base 50°F) to ripen. The state median runs ~3770 GDD (from PRISM 1991-2020 climate normals), so Missouri'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
Sunflower likes near-neutral soil (pH 5.5-8). That's the common-ground band across Missouri's silt loam and clay loam — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6 and 7.5 — worth knowing before you decide whether a Missouri soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Missouri 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. Missouri soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Sunflower in Missouri
Zone compatibility tells you about winter cold survival — but Missouri growers also need to think about:
Highly variable weather with late frosts and early heat
Heavy clay soils in many regions
Ozark soils are thin and rocky
What to actually do about these — and the constraints that apply to every Missouri grower, not just sunflower — is covered on the Missouri growing guide.
Timing shifts within Missouri
Sunflower needs about 70 days of frost-free season to complete its cycle. Even Crawford County — Missouri’s shortest season at 192 frost-free days — clears that by 122 days, so season length isn’t the constraint anywhere in Missouri. What varies is your own parcel.
Across Missouri’s 115 counties the frost-free season runs from 192 days in Crawford County to 258 days in Pemiscot County — a spread of 66 days, which is why a single statewide planting date misleads. The median Missouri county sees 219 frost-free days, leaving sunflower about 149 days of slack on a typical parcel — room for a second sowing where the season runs long.
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"). Sunflower's 70-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
Sunflower 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, sunflower can only work that bloom inside Missouri's frost window — roughly 219 days, opening after the last 28°F freeze (Mar 27 - Apr 2) and closing at the first (Oct 31 - Nov 7), per NOAA Regional Climate Centers ACIS, 1991-2020.
Missouri Cooperative Extension
For Missouri-specific cultivar recommendations, planting calendars, and pest pressure for sunflower, the canonical source is MU Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Sunflower native to Missouri?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Sunflower as native to Missouri. 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 Sunflower in Missouri
When can I plant Sunflower in Missouri?
Missouri's last spring hard freeze (28°F) clears between Mar 27 and Apr 2, and the first fall hard freeze lands between Oct 31 and Nov 7 (NOAA Regional Climate Centers ACIS, 1991-2020). Sunflower 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 Sunflower mature before first frost in Missouri?
Yes — Sunflower matures in 80 days (Growable Ground Plant Database), and Missouri's dependable hard-freeze-free window runs 212 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 132 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 Sunflower grown in across Missouri?
Missouri spans USDA hardiness zones 5b-8a (USDA ARS PHZM 2023). Sunflower 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 Missouri site have?
A typical Missouri site sees ~219 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Sunflower needs 70+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Sunflower native to Missouri?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Sunflower as native to Missouri. Planting it supports the pollinators and wildlife that evolved alongside it.
How should I amend the soil for Sunflower in Missouri?
Sunflower prefers pH 5.5-8 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Missouri soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Sunflower actually grow on my specific land in Missouri?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores sunflower 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 Missouri
State-level data is a sketch. Your Growable Ground report scores sunflower against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Missouri sunflower averages can't show:
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