Yes — Strong Match
clethra (zones 5-11) covers every zone Indiana contains (5b-7b), so hardiness is not what limits it anywhere in the state.
Clethra in Indiana — the short answer
Clethra in Indiana: hardy in zones 5–11, part sun, against a state median of ~209 frost-free days.
- Plant zones
- 5-11
- 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
- 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
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 clethra 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 full report in seconds
Indiana is not one climate
Indiana’s winter-low ladder runs across 92 counties, from zone 5.5 in Benton County to zone 7 in Warrick County. That is 15°F between the two counties’ average coldest night — the difference between clethra overwintering in the ground and coming under cover.
The middle half of 92 counties runs 6–6.5 zones, with a median of 6 zones — a 1.5-zone span end to end.
Measured across 92 Indiana counties. USDA PHZM 2023, per county. 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 Indiana Fits Best
Even within Indiana's zones 5b-7b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for clethra (USDA PHZM 2023):
Zone Comparison
Clethra Needs
- USDA Zones: 5-11
- Frost-Free Days: 150+
- Sun: Part Sun
- Mature size: 8 ft tall
- 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 5-11)
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 Clethra 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.
Winter standing
Indiana runs as cold as USDA zone 5, and no sourced winter-hardiness floor is on record for clethra, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether clethra 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.
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 clethra survives winter here. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Clethra wants 150+ frost-free days; a typical Indiana site sees ~209 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves a workable window — start indoors to bank time.
Chill hours
Clethra requires ~500 chill hours (32-45°F dormancy window). Indiana typically banks ~2500 chill hours per winter (from PRISM 1991-2020 climate normals), which keeps this plant on track.
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
Clethra likes near-neutral soil (pH 4.5-7). That's the common-ground band across Indiana's silt loam and clay loam — a soil test confirms it for your site.
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 Clethra 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
What to actually do about these — and the constraints that apply to every Indiana grower, not just clethra — is covered on the Indiana growing guide.
Timing shifts within Indiana
Clethra needs about 150 days of frost-free season to complete its cycle. Even Steuben County — Indiana’s shortest season at 191 frost-free days — clears that by 41 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"). Clethra's 150-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
Clethra 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, clethra 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.
Indiana Cooperative Extension
For Indiana-specific cultivar recommendations, planting calendars, and pest pressure for clethra, the canonical source is Purdue Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Clethra native to Indiana?
Clethra is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in Indiana. It can still earn a place in a Indiana garden — the zone comparison above tells you whether it will thrive.
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 Clethra in Indiana
When can I plant Clethra 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 Clethra, 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 Clethra grown in across Indiana?
Indiana spans USDA hardiness zones 5b-7b (USDA ARS PHZM 2023). Clethra carries a range of zones 5-11, 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). Clethra needs 150+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Clethra native to Indiana?
Clethra is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in Indiana. It can still earn a place in a Indiana garden — the zone comparison above tells you whether it will thrive.
How should I amend the soil for Clethra in Indiana?
Clethra prefers pH 4.5-7 (USDA PLANTS). 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 Clethra actually grow on my specific land in Indiana?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores clethra 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 clethra against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Indiana clethra 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 clethra average
Explore More
Growing guides for clethra
Last updated: