Yes — Strong Match
Thai basil 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 ~80 Thai basil needs.
Sow by about Aug 29
Thai Basil is grown as an annual, so what decides it here is season length, not a winter zone. It needs about 80 frost-free days and a typical Indiana season runs ~209 frost-free days, leaving 129 days of slack. That is room to sow as late as about Aug 29 and still finish before the usual first freeze (Nov 2).
Want more weeks at either end of that window? How to buy the weeks →
80 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.
Thai Basil in Indiana — the short answer
Thai Basil in Indiana: hardy in zones 10–11, full sun, against a state median of ~209 frost-free days.
- Plant zones
- 10-11
- Not verified
- 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.
Indiana spans zones 5b-7b, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score thai basil against your parcel's actual hardiness, soil, and sun.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your parcel report in seconds — read in full free for your first 14 days
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 thai basil 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
Thai Basil Needs
- USDA Zones: 10-11
- Frost-Free Days: 80+
- Sun: Full Sun
- Mature size: 1.5 ft tall
- Picking window: ~90 days of harvest
- Drought tolerance: Low
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
Plant Zone Range (zones 10-11)
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 Thai Basil 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.
When to start the seed
Those dates are when thai basil goes out, not when it starts. It is sown under cover about 6 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.
Winter standing
Indiana runs as cold as USDA zone 5, and no sourced winter-hardiness floor is on record for thai basil, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether thai basil is a permanent planting or a replant-every-spring crop for you turns on your own zone within Indiana; check its hardiness range against that before treating it as long-lived ground.
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
Thai Basil wants 80+ 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
Thai Basil needs ~1500 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
Thai Basil tolerates a wide pH range (pH 4.3-8.2) — 3.9 units, acid ground through alkaline — so soil acidity is rarely what limits it in Indiana. A soil test is still worth having, but for what else it tells you about this site, not to clear this plant. 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. Thai Basil has low drought tolerance, so it is the fast-draining end that will 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.
Before you plant thai basil for food
Anything you grow to eat takes up what is in the ground it grows in, so what is on record near you is worth knowing before thai basil goes in. What follows is Indiana’s documented federal record at state scale — a screening signal, not a soil test, and not a statement about any one lot.
Safe to Grow Here?
What the federal record shows across Indiana — and how to grow with it.
We checked the federal record across Indiana — 33,216 documented sites across 8 of the 8 source types we track.
The most significant on record: 423 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Indiana carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources Checked
across Indiana
Severity Distribution
across Indiana
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Indiana, two things run higher than the national average across Indiana — Toxics Release Inventory (2,883 sites) and Superfund (423 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 8 federal source types.
What Else to Consider for Thai Basil 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 thai basil here specifically
Thai Basil roots run shallow and prefer pH 4.3–8.2, but drainage comes first here: SSURGO maps about 37.8% of Indiana as poorly or somewhat-poorly drained, and wet ground rots its crown before pH ever matters.
Plant thai basil on a raised, gravel-amended berm so water drains fast and the crown stays dry. How to handle it →
What to actually do about these — and the constraints that apply to every Indiana grower, not just thai basil — 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 thai basil to your county's window, not the statewide date.
Thai Basil needs about 80 days of frost-free season to complete its cycle. Even Steuben County — Indiana’s shortest season at 191 frost-free days — clears that by 111 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"). Thai Basil's 80-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
Thai Basil draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, thai basil 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 Thai Basil Varieties for Indiana
Indiana publishes no state variety trial for thai basil, 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 thai basil, the canonical source is Purdue Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Thai Basil native to Indiana?
No — the USDA PLANTS Database lists Thai Basil 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 Thai Basil in Indiana
When can I plant Thai Basil 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). No sourced winter-hardiness floor is on record for Thai Basil, so this page does not state whether it overwinters in Indiana and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Thai Basil grown in across Indiana?
Indiana spans USDA hardiness zones 5b-7b (USDA ARS PHZM 2023). Thai Basil carries a range of zones 10-11, 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). Thai Basil needs 80+ 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 Thai Basil native to Indiana?
No — the USDA PLANTS Database lists Thai Basil 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 Thai Basil in Indiana?
Thai Basil tolerates pH 4.3-8.2 and well (dry spells) drainage (FAO ECOCROP). That is a 3.9-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Indiana site — amend for drainage and organic matter first.
Will Thai Basil actually grow on my specific land in Indiana?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores thai basil 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 thai basil against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Indiana thai basil 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 thai basil average
Explore More
Growing guides for thai basil
Explore Indiana county by county
Indiana carries 92 counties with their own USDA zone — a sample of the growing pages for thai basil there:
Where else thai basil grows
Thai Basil'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 891 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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