Generally — Most Areas
black-eyed Susan (zones 3-7) suits most of Idaho (3b-8a) — zones 3-7 are in range, and the rest of the state is the exception.
Black Eyed Susan in Idaho — the short answer
Black Eyed Susan in Idaho: hardy in zones 3–7, full sun, against a state median of ~160 frost-free days.
- Plant zones
- 3-7
- 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
- Idaho zones
- 3b-8a
- USDA PHZM 2023
- Frost window
- Apr 26 - May 17 – Oct 1 - Oct 17
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 94 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 120 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.
Idaho spans zones 3b-8a, but your yard has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score black eyed susan against your land's actual soil, sun, and frost.
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Idaho is not one climate
A single Idaho answer averages 44 counties whose growing seasons are 122 days apart — from 94 frost-free days in Valley County to 216 in Nez Perce County. Which end of that your land sits nearer changes what black eyed susan can finish before the first hard freeze.
The middle half of 44 counties runs 133–174 days, with a median of 159 days — a 122-day span end to end.
Measured across 44 Idaho 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 Idaho Fits Best
Even within Idaho's zones 3b-8a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for black eyed susan (USDA PHZM 2023):
Zone Comparison
Black Eyed Susan Needs
- USDA Zones: 3-7
- Sun: Full Sun
- Mature size: 1 ft tall
- Picking window: ~45 days of harvest
- Drought tolerance: Medium
Idaho Has
- USDA Zones: 3b-8a
- Last Hard Freeze (28°F): Apr 26 - May 17
- First Hard Freeze (28°F): Oct 1 - Oct 17
- Annual Rainfall: 8-35 inches
- Common Soils: Volcanic ash, Silt loam, Sandy loam
Plant Zone Range (zones 3-7)
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 Black Eyed Susan in Idaho
The frost window
Across Idaho, the last spring hard freeze (28°F) clears between Apr 26 and May 17, and the first fall hard freeze lands between Oct 1 and Oct 17 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 137-day window you can count on — up to 174 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
Black Eyed Susan 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 black eyed susan goes out, not when it starts. It is sown under cover about 8 weeks ahead, so counting back from Idaho's late-side last freeze of May 17 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 120 days to maturity (Growable Ground Plant Database), one crop fits Idaho's 137-day dependable window with 17 days of margin — plant at the front of the window to keep that cushion.
Timing tuned to sub-state frost dates — Valley 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 black eyed susan survives winter in part of Idaho, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Days to maturity
Black Eyed Susan matures in ~120 days (Growable Ground Plant Database). A typical Idaho site has ~160 frost-free days, so one full crop fits, with little room for replant.
Growing degree days
Black Eyed Susan needs ~1000 GDD (base 50°F) to ripen. The state median runs ~1187 GDD (from PRISM 1991-2020 climate normals), so Idaho sits right at the threshold — pay attention to siting and microclimate.
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
Black Eyed Susan likes near-neutral soil (pH 5.5-8). That's the common-ground band across Idaho's volcanic ash and silt loam — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6.5 and 7.5 — worth knowing before you decide whether a Idaho soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Idaho site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
Idaho's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel. Black Eyed Susan 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 black eyed susan 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. Idaho soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Black Eyed Susan in Idaho
Zone compatibility tells you about winter cold survival — but Idaho growers also need to think about:
Short growing season at higher elevations
Arid conditions require irrigation in most of the state
Cold winter snaps can reach -30F in mountain valleys
Growing black eyed susan here specifically
Idaho's soils run mostly silt loam (Mollisols), and whether that suits black eyed susan's pH 5.5–8.0 preference comes down to your exact parcel, not the statewide picture.
Pull your parcel's SSURGO map unit, test pH, and amend toward black eyed susan's 5.5–8.0 target before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Idaho grower, not just black eyed susan — is covered on the Idaho growing guide.
Timing shifts within Idaho
Idaho isn't one climate. In Valley County, the last hard freeze (28°F) holds until about Jun 14 — roughly 42 days later than the recorded state median — so plant black eyed susan to your county's window, not the statewide date.
Black Eyed Susan needs about 120 days of frost-free season from planting to harvest. 39 of Idaho’s 44 counties give it that outright. The tightest that does is Butte County at 123 frost-free days — 3 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
Across Idaho’s 44 counties the frost-free season runs from 94 days in Valley County to 216 days in Nez Perce County — a spread of 122 days, which is why a single statewide planting date misleads. The median Idaho county sees 160 frost-free days, leaving black eyed susan about 40 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"). Black Eyed Susan's 120-day requirement: USDA PLANTS / Growable Ground plant database (days to maturity). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Black Eyed Susan 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, black eyed susan can only work that bloom inside Idaho's frost window — roughly 160 days, opening after the last 28°F freeze (Apr 26 - May 17) and closing at the first (Oct 1 - Oct 17), per NOAA Regional Climate Centers ACIS, 1991-2020.
Recommended Black Eyed Susan Varieties for Idaho
Idaho publishes no state variety trial for black eyed susan, so we won't invent a "best for Idaho" list. Choose types rated to your USDA hardiness zone (3b-8a), and confirm winter survival and drainage against your own parcel.
Idaho Cooperative Extension
For Idaho-specific cultivar recommendations, planting calendars, and pest pressure for black eyed susan, the canonical source is University of Idaho Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Black Eyed Susan native to Idaho?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Black Eyed Susan as native to Idaho. 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 Black Eyed Susan in Idaho
When can I plant Black Eyed Susan in Idaho?
Idaho's last spring hard freeze (28°F) clears between Apr 26 and May 17, and the first fall hard freeze lands between Oct 1 and Oct 17 (NOAA Regional Climate Centers ACIS, 1991-2020). Black Eyed Susan 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 Black Eyed Susan mature before first frost in Idaho?
Yes — Black Eyed Susan matures in 120 days (Growable Ground Plant Database), and Idaho's dependable hard-freeze-free window runs 137 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 17 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 Black Eyed Susan grown in across Idaho?
Idaho spans USDA hardiness zones 3b-8a (USDA ARS PHZM 2023). Black Eyed Susan carries a range of zones 3-7, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Idaho site have?
A typical Idaho site sees ~160 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Black Eyed Susan should be matched against that window, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Valley, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Black Eyed Susan native to Idaho?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Black Eyed Susan as native to Idaho. Planting it supports the pollinators and wildlife that evolved alongside it.
How should I amend the soil for Black Eyed Susan in Idaho?
Black Eyed Susan prefers pH 5.5-8 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Idaho soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Black Eyed Susan actually grow on my specific land in Idaho?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores black eyed susan 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 Idaho
State-level data is a sketch. Your Growable Ground report scores black eyed susan against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Idaho black eyed susan averages can't show:
We read public map data around Idaho — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Idaho black eyed susan average
Explore More
Growing guides for black eyed susan
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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