Yes — Strong Match
zinnia is grown as an annual, so season length decides it here, not a winter zone — and Indiana's typical season runs ~209 frost-free days against the ~60 zinnia needs.
Sow by about Aug 29
Zinnia 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 Indiana season runs ~209 frost-free days, leaving 149 days of slack. That is room to sow as late as about Aug 29 and still finish before the usual first freeze (Nov 2), 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 Indiana’s ~209-day season. NOAA Regional Climate Centers ACIS 1991-2020 (28°F killing freeze), state median across counties, via stateClimateData.ts.
Zinnia in Indiana — the short answer
Zinnia in Indiana: full sun, against a state median of ~209 frost-free days.
- Indiana zones
- 5b-7b
- USDA PHZM 2023
- Frost window
- Apr 4 - Apr 9 – Oct 30 - Nov 4
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 191 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 65 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.
Zinnia is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Indiana site runs ~209 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 zinnia 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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Indiana is not one climate
A single Indiana answer averages 92 counties whose growing seasons are 41 days apart — from 191 frost-free days in Steuben County to 232 in Posey County. Which end of that your land sits nearer changes what zinnia can finish before the first hard freeze.
The middle half of 92 counties runs 203–214 days, with a median of 209 days — a 41-day span end to end.
Measured across 92 Indiana 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.
Zone Comparison
Zinnia Needs
- USDA Zones: Data pending
- Frost-Free Days: 60+
- Sun: Full Sun
- Mature size: 3 ft tall
- Picking window: ~120 days of harvest
- Drought tolerance: Medium
Indiana Has
- USDA Zones: 5b-7b
- Last Hard Freeze (28°F): Apr 4 - Apr 9
- First Hard Freeze (28°F): Oct 30 - Nov 4
- Annual Rainfall: 36-46 inches
- Common Soils: Silt loam, Clay loam, Glacial till
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 Zinnia in Indiana
The frost window
Across Indiana, the last spring hard freeze (28°F) clears between Apr 4 and Apr 9, and the first fall hard freeze lands between Oct 30 and Nov 4 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 204-day window you can count on — up to 214 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
Zinnia 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 zinnia goes out, not when it starts. It is sown under cover about 4 weeks ahead, so counting back from Indiana's late-side last freeze of Apr 9 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 65 days to maturity (Growable Ground Plant Database), counting from the last hard freeze it ripens with 139 days to spare even in Indiana's tightest freeze scenario — room for a later start or a second sowing.
Timing tuned to sub-state frost dates — Steuben 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
Frost-free days
Zinnia wants 60+ frost-free days; a typical Indiana site sees ~209 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Zinnia needs ~800 GDD (base 50°F) to ripen. The state median runs ~3153 GDD (from PRISM 1991-2020 climate normals), so Indiana'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
Zinnia likes near-neutral soil (pH 5.5-7.5). That's the common-ground band across Indiana'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 — worth knowing before you decide whether a Indiana soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Indiana site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
SSURGO maps about 37.8% of Indiana as poorly or somewhat-poorly drained, and the class flips parcel to parcel. Zinnia sits mid-range for drought tolerance, so either extreme can cost you — your soil map unit, not the state average, is the real answer.
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. Indiana soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Zinnia in Indiana
Zone compatibility tells you about winter cold survival — but Indiana growers also need to think about:
Heavy clay soils limit drainage in many areas
Late spring frosts through early May
Hot humid summers promote blight and mildew
Growing zinnia here specifically
Zinnia likes pH 5.5–7.5 and its growing tissue burns around 32°F (FAO ECOCROP), yet neither saves it from wet feet — SSURGO maps about 37.8% of Indiana poorly-drained, where its roots sit and rot.
Set zinnia high on bermed, grit-amended ground so winter and storm water drain away from the roots. How to handle it →
What to actually do about these — and the constraints that apply to every Indiana grower, not just zinnia — is covered on the Indiana growing guide.
Timing shifts within Indiana
Indiana isn't one climate. In Steuben County, the last hard freeze (28°F) holds until about Apr 18 — roughly 11 days later than the recorded state median — so plant zinnia to your county's window, not the statewide date.
Zinnia needs about 60 days of frost-free season to complete its cycle. Even Steuben County — Indiana’s shortest season at 191 frost-free days — clears that by 131 days, so season length isn’t the constraint anywhere in Indiana. 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"). Zinnia'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
Zinnia draws honeybees, native bees, butterflies, and hummingbirds (high value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, zinnia can only work that bloom inside Indiana's frost window — roughly 209 days, opening after the last 28°F freeze (Apr 4 - Apr 9) and closing at the first (Oct 30 - Nov 4), per NOAA Regional Climate Centers ACIS, 1991-2020.
Recommended Zinnia Varieties for Indiana
Indiana publishes no state variety trial for zinnia, so we won't invent a "best for Indiana" list. Choose types rated to your USDA hardiness zone (5b-7b), and confirm winter survival and drainage against your own parcel.
Indiana Cooperative Extension
For Indiana-specific cultivar recommendations, planting calendars, and pest pressure for zinnia, the canonical source is Purdue Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Zinnia native to Indiana?
No — the USDA PLANTS Database lists Zinnia as introduced rather than native in the Lower 48, so it is not part of Indiana's native flora. It grows here as a garden plant; pairing it with a few Indiana natives keeps local pollinators fed too.
Looking for plants that belong here? The Indiana growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Zinnia in Indiana
When can I plant Zinnia in Indiana?
Indiana's last spring hard freeze (28°F) clears between Apr 4 and Apr 9, and the first fall hard freeze lands between Oct 30 and Nov 4 (NOAA Regional Climate Centers ACIS, 1991-2020). Zinnia 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 Zinnia mature before first frost in Indiana?
Yes — Zinnia matures in 65 days (Growable Ground Plant Database), and Indiana's dependable hard-freeze-free window runs 204 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 139 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 Zinnia grown in across Indiana?
Indiana spans USDA hardiness zones 5b-7b (USDA ARS PHZM 2023). Zinnia 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 Indiana site have?
A typical Indiana site sees ~209 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Zinnia needs 60+ 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 Steuben, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Zinnia native to Indiana?
No — the USDA PLANTS Database lists Zinnia as introduced rather than native in the Lower 48, so it is not part of Indiana's native flora. It grows here as a garden plant; pairing it with a few Indiana natives keeps local pollinators fed too.
How should I amend the soil for Zinnia in Indiana?
Zinnia prefers pH 5.5-7.5 and well (dry spells) drainage (Growable Ground Plant Database). That sits in the common-ground band across Indiana soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Zinnia actually grow on my specific land in Indiana?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores zinnia 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 Indiana
State-level data is a sketch. Your Growable Ground report scores zinnia against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Indiana zinnia averages can't show:
We read public map data around Indiana — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Indiana zinnia average
Explore More
Growing guides for zinnia
Explore Indiana county by county
Indiana carries 92 counties with their own USDA zone — a sample of the growing pages for zinnia there:
Where else zinnia grows
Zinnia's zone band crosses state lines — these are the states closest to Indiana 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 Indiana
Indiana has a growing page for 893 plants — a rotating sample of the rest of the shelf.
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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