Yes — Strong Match
phacelia is grown in zones 2-11, which covers every zone Kentucky contains (6a-7b). Whether the season is long enough is the question that remains.
Phacelia in Kentucky — the short answer
Phacelia in Kentucky: grown in zones 2–11, full sun, against a state median of ~221 frost-free days.
- Plant zones
- Grown as an annual — see the growing season
- Growing season, not a hardiness zone
- Kentucky zones
- 6a-7b
- USDA PHZM 2023
- Frost window
- Mar 27 - Apr 2 – Nov 4 - Nov 10
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 195 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 45 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.
Phacelia is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Kentucky site runs ~221 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 phacelia 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.
No card required · your parcel report in seconds — read in full free for your first 14 days
Kentucky is not one climate
A single Kentucky answer averages 120 counties whose growing seasons are 50 days apart — from 195 frost-free days in Greenup County to 245 in Jefferson County. Which end of that your land sits nearer changes what phacelia can finish before the first hard freeze.
The middle half of 120 counties runs 216–227 days, with a median of 221 days — a 50-day span end to end.
Measured across 120 Kentucky 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 Kentucky Fits Best
Even within Kentucky's zones 6a-7b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for phacelia (USDA PHZM 2023):
Zone Comparison
Phacelia Needs
- USDA Zones: 2-11
- Frost-Free Days: 100+
- Sun: Full Sun
- Mature size: 3 ft tallWe haven't confirmed this against a published source yet.
- Picking window: ~30 days of harvestWe haven't confirmed this against a published source yet.
- Drought tolerance: Medium
Kentucky Has
- USDA Zones: 6a-7b
- Last Hard Freeze (28°F): Mar 27 - Apr 2
- First Hard Freeze (28°F): Nov 4 - Nov 10
- Annual Rainfall: 42-52 inches
- Common Soils: Silt loam, Clay loam, Limestone-derived
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 Phacelia in Kentucky
The frost window
Across Kentucky, the last spring hard freeze (28°F) clears between Mar 27 and Apr 2, and the first fall hard freeze lands between Nov 4 and Nov 10 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 216-day window you can count on — up to 228 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 hardiness
Phacelia takes cold down to about 18°F before a freeze kills it, so you can plant on the early side of Kentucky's window — even a few weeks before the final hard freeze. 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. We haven't confirmed this against a published source yet.
When to start the seed
Phacelia is direct-sown where it grows rather than started under cover, so there is no seed-tray head start to bank — Kentucky's dates above are the whole calendar for it. That makes the last-freeze date the binding constraint, and a warmer pocket of your own yard is worth more to this crop than it is to a transplanted one.
Days to maturity vs. the window
At 45 days to maturity (Growable Ground Plant Database), counting from the last hard freeze it ripens with 171 days to spare even in Kentucky's tightest freeze scenario — room for a later start or a second sowing.
Timing tuned to sub-state frost dates — Greenup 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
Phacelia is grown in zones 2–11, which covers every zone Kentucky contains (6a-7b). It is grown as a summer crop, so season length decides it here. Kentucky's typical season runs ~221 frost-free days against the ~100 phacelia needs.
Frost-free days
Phacelia wants 100+ frost-free days; a typical Kentucky site sees ~221 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Phacelia needs ~1000 GDD (base 50°F) to ripen. We haven't confirmed this against a published source yet. The state median runs ~3689 GDD (from PRISM 1991-2020 climate normals), so Kentucky'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
Phacelia likes near-neutral soil (pH 6.4-8.6). That's the common-ground band across Kentucky'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 7.5 — worth knowing before you decide whether a Kentucky soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Kentucky site is heavier clay or sits in a low spot, a raised bed lifts the roots above wet ground, or work in compost. Preferred pH and drainage need: We haven't confirmed this against a published source yet.
Your land, not the state average
Kentucky soil pH runs about 5.5–6.3, and that sits below phacelia's tolerated 6.4–8.6, so the typical Kentucky parcel needs lime before it will perform. SSURGO maps it swinging by full points parcel to parcel, so your map unit, not the state number, decides whether phacelia needs lime or sulfur.
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. Kentucky soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Phacelia in Kentucky
The zone range tells you where phacelia is grown — but Kentucky growers also need to think about:
Heavy clay soils in the Bluegrass region
High humidity promotes fungal diseases
Karst topography creates drainage unpredictability
Growing phacelia here specifically
Phacelia wants soil pH 6.4–8.6, but Kentucky's soils run acidic (SSURGO maps a dominant pH near 5.9) — below its range, nutrients lock up and growth stalls.
Test your soil and lime to raise pH into phacelia's 6.4–8.6 range before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Kentucky grower, not just phacelia — is covered on the Kentucky growing guide.
Timing shifts within Kentucky
Kentucky isn't one climate. In Greenup County, the last hard freeze (28°F) holds until about Apr 13 — roughly 13 days later than the recorded state median — so plant phacelia to your county's window, not the statewide date.
Phacelia needs about 100 days of frost-free season to complete its cycle. Even Greenup County — Kentucky’s shortest season at 195 frost-free days — clears that by 95 days, so season length isn’t the constraint anywhere in Kentucky. 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"). Phacelia's 100-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
Phacelia draws honeybees, native bees, and butterflies (high value). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, phacelia can only work that bloom inside Kentucky's frost window — roughly 221 days, opening after the last 28°F freeze (Mar 27 - Apr 2) and closing at the first (Nov 4 - Nov 10), per NOAA Regional Climate Centers ACIS, 1991-2020. Pollinator value: We haven't confirmed this against a published source yet.
Kentucky Cooperative Extension
For Kentucky-specific cultivar recommendations, planting calendars, and pest pressure for phacelia, the canonical source is University of Kentucky Cooperative Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Phacelia native to Kentucky?
Phacelia is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-10-19) does not record it growing in Kentucky. It can still earn a place in a Kentucky garden — the zone comparison above tells you whether it will thrive.
Looking for plants that belong here? The Kentucky growing guide lists plants that USDA PLANTS records growing in Kentucky and that Kew and NatureServe Explorer both list in its native range, leaving out any that NatureServe flags as exotic there or that our audit holds.
State records: USDA PLANTS Database state-distribution data (presence, not state-level nativity), accessed 2026-10-19.
Common Questions About Growing Phacelia in Kentucky
When can I plant Phacelia in Kentucky?
Kentucky's last spring hard freeze (28°F) clears between Mar 27 and Apr 2, and the first fall hard freeze lands between Nov 4 and Nov 10 (NOAA Regional Climate Centers ACIS, 1991-2020). Time outdoor planting to after the last hard freeze for your specific site — a further two to three weeks for anything tender — and count back from those dates for transplant scheduling.
Can Phacelia mature before first frost in Kentucky?
Yes — Phacelia matures in 45 days (Growable Ground Plant Database), and Kentucky's dependable hard-freeze-free window runs 216 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 171 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 Phacelia grown in across Kentucky?
Kentucky spans USDA hardiness zones 6a-7b (USDA ARS PHZM 2023). Phacelia 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 Kentucky site have?
A typical Kentucky site sees ~221 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Phacelia needs 100+ 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 Greenup, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Phacelia native to Kentucky?
Phacelia is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-10-19) does not record it growing in Kentucky. It can still earn a place in a Kentucky garden — the zone comparison above tells you whether it will thrive.
How should I amend the soil for Phacelia in Kentucky?
Phacelia prefers pH 6.4-8.6 and well (dry spells) drainage. We haven't confirmed this against a published source yet. That sits in the common-ground band across Kentucky soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Phacelia actually grow on my specific land in Kentucky?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores phacelia against your address's mapped soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Kentucky
State-level data is a sketch. Your Growable Ground report scores phacelia against your land's mapped soil, modelled sun, drainage, and frost data — not zone averages.
Three things about your lot that Kentucky phacelia averages can't show:
We read public map data around Kentucky — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Kentucky phacelia average
Explore More
Growing guides for phacelia
Explore Kentucky county by county
Kentucky carries 120 counties with their own USDA zone — a sample of the growing pages for phacelia there:
Where else phacelia grows
Phacelia's zone band crosses state lines — these are the states closest to Kentucky 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 Kentucky
Kentucky has a growing page for 889 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
Last updated: