Yes — Strong Match
sunflower (zones 2-11) covers every zone Kansas contains (5b-7a), so hardiness is not what limits it anywhere in the state.
Sunflower in Kansas — the short answer
Sunflower in Kansas: hardy in zones 2–11, full sun, against a state median of ~208 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
- Kansas zones
- 5b-7a
- USDA PHZM 2023
- Frost window
- Apr 1 - Apr 12 – Oct 25 - Nov 3
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 177 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 Kansas site runs ~208 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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Kansas is not one climate
A single Kansas answer averages 105 counties whose growing seasons are 54 days apart — from 177 frost-free days in Greeley County to 231 in Crawford County. Which end of that your land sits nearer changes what sunflower can finish before the first hard freeze.
The middle half of 105 counties runs 197–216 days, with a median of 208 days — a 54-day span end to end.
Measured across 105 Kansas 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 Kansas Fits Best
Even within Kansas's zones 5b-7a, 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
Kansas Has
- USDA Zones: 5b-7a
- Last Hard Freeze (28°F): Apr 1 - Apr 12
- First Hard Freeze (28°F): Oct 25 - Nov 3
- Annual Rainfall: 16-42 inches
- Common Soils: Prairie loam, Silt loam, Clay
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 Kansas
The frost window
Across Kansas, the last spring hard freeze (28°F) clears between Apr 1 and Apr 12, and the first fall hard freeze lands between Oct 25 and Nov 3 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 196-day window you can count on — up to 216 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 Kansas's late-side last freeze of Apr 12 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 116 days to spare even in Kansas's tightest freeze scenario — room for a later start or a second sowing.
Timing tuned to sub-state frost dates — Greeley County, not the statewide average.
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 Kansas site sees ~208 (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 ~3821 GDD (from PRISM 1991-2020 climate normals), so Kansas'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 Kansas's prairie 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 7.5 — worth knowing before you decide whether a Kansas soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Kansas site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
Kansas's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel. Sunflower needs about 19 inches of workable depth, so it is that horizon — not the surface — you are testing for. That map unit, not the state average, decides how sunflower performs.
Check your parcel → Source: USDA NRCS SSURGO.
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. Kansas 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 Kansas
Zone compatibility tells you about winter cold survival — but Kansas growers also need to think about:
Low rainfall in western KS requires irrigation
Extreme wind and hail during severe storm season
Hot dry summers with 100F+ days
Growing sunflower here specifically
Sunflower prefers pH 5.5–8.0 and room to root medium; across much of Kansas, restrictive group-D subsoil (SSURGO) blocks that depth.
Build sunflower a deep raised bed of loose soil to bypass the dense subsoil entirely. How to handle it →
What to actually do about these — and the constraints that apply to every Kansas grower, not just sunflower — is covered on the Kansas growing guide.
Timing shifts within Kansas
Kansas isn't one climate. In Greeley County, the last hard freeze (28°F) holds until about Apr 23 — roughly 18 days later than the recorded state median — so plant sunflower to your county's window, not the statewide date.
Sunflower needs about 70 days of frost-free season to complete its cycle. Even Greeley County — Kansas’s shortest season at 177 frost-free days — clears that by 107 days, so season length isn’t the constraint anywhere in Kansas. 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"). 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 Kansas's frost window — roughly 208 days, opening after the last 28°F freeze (Apr 1 - Apr 12) and closing at the first (Oct 25 - Nov 3), per NOAA Regional Climate Centers ACIS, 1991-2020.
Recommended Sunflower Varieties for Kansas
Kansas publishes no state variety trial for sunflower, so we won't invent a "best for Kansas" list. Choose types rated to your USDA hardiness zone (5b-7a), and confirm winter survival and drainage against your own parcel.
Kansas Cooperative Extension
For Kansas-specific cultivar recommendations, planting calendars, and pest pressure for sunflower, the canonical source is K-State Research and Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Sunflower native to Kansas?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Sunflower as native to Kansas. 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 Kansas
When can I plant Sunflower in Kansas?
Kansas's last spring hard freeze (28°F) clears between Apr 1 and Apr 12, and the first fall hard freeze lands between Oct 25 and Nov 3 (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 Kansas?
Yes — Sunflower matures in 80 days (Growable Ground Plant Database), and Kansas's dependable hard-freeze-free window runs 196 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 116 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 Kansas?
Kansas spans USDA hardiness zones 5b-7a (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 Kansas site have?
A typical Kansas site sees ~208 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. In cooler counties like Greeley, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Sunflower native to Kansas?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Sunflower as native to Kansas. Planting it supports the pollinators and wildlife that evolved alongside it.
How should I amend the soil for Sunflower in Kansas?
Sunflower prefers pH 5.5-8 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Kansas 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 Kansas?
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 Kansas
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 Kansas sunflower averages can't show:
We read public map data around Kansas — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Kansas sunflower 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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