Generally — Most Areas
hyssop (zones 3-9) suits most of Oregon (5a-10a) — zones 5-9 are in range, and the rest of the state is the exception.
Your yard isn't the whole zone.
Oregon spans zones 5a-10a, 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 hyssop against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Hyssop Needs
- USDA Zones: 3-9
- Frost-Free Days: 180+
- Sun: Part Sun
- Mature size: 2 ft tall
- Picking window: ~90 days of harvest
- Drought tolerance: Medium
Oregon Has
- USDA Zones: 5a-10a
- Last Hard Freeze (28°F): Feb 25 - Apr 26
- First Hard Freeze (28°F): Oct 19 - Nov 26
- Annual Rainfall: 8-90 inches
- Common Soils: Volcanic, Silt loam (Willamette), Sandy loam
Plant Zone Range (zones 3-9)
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Hyssop in Oregon
The frost window
Across Oregon, the last spring hard freeze (28°F) clears between Feb 25 and Apr 26, and the first fall hard freeze lands between Oct 19 and Nov 26 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 176-day window you can count on — up to 274 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 hyssop goes out, not when it starts. It is sown under cover about 8 weeks ahead, so counting back from Oregon's late-side last freeze of Apr 26 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Establishment timing
As a long-lived plant, hyssop isn't racing the calendar to a harvest date. Plant it in spring once the last hard-freeze window passes so roots settle in through the full season, or in early fall while the soil still holds summer warmth.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: USDA PLANTS Database. 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 hyssop survives winter in part of Oregon, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Hyssop wants 180+ frost-free days; a typical Oregon site sees ~213 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves a workable window — start indoors to bank time.
Growing degree days
Hyssop needs ~900 GDD (base 50°F) to ripen. The state median runs ~1666 GDD (from PRISM 1991-2020 climate normals), so Oregon'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
Hyssop tolerates a wide pH range (pH 5.5-8.5) — 3 units, acid ground through alkaline — so soil acidity is rarely what limits it in Oregon. 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 7.5 — worth knowing before you decide whether a Oregon soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells), excessive (dry/moderately dry). If your Oregon site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Plant pH and drainage requirements from USDA PLANTS Database. Oregon soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Hyssop in Oregon — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 3-9 (USDA PLANTS Database)
- State Zones: 5a-10a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Feb 25 - Apr 26 to Oct 19 - Nov 26 (NOAA Regional Climate Centers ACIS, 1991-2020)
- Days to Maturity: 85 days
What Else to Consider for Hyssop in Oregon
Zone compatibility tells you about winter cold survival — but Oregon growers also need to think about:
West side: excessive rain and overcast skies reduce sun for warm-season crops
East side: arid conditions (8-15 inches rainfall) require irrigation
Slug pressure is extreme in western Oregon
Mountain areas have very short seasons (60-90 frost-free days)
What to actually do about these — and the constraints that apply to every Oregon grower, not just hyssop — is covered on the Oregon growing guide.
Timing shifts within Oregon
Hyssop needs about 180 days of frost-free season to complete its cycle. 26 of Oregon’s 36 counties give it that outright. The tightest that does is Malheur County at 182 frost-free days — 2 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
Across Oregon’s 36 counties the frost-free season runs from 86 days in Klamath County to 308 days in Lincoln County — a spread of 222 days, which is why a single statewide planting date misleads. The median Oregon county sees 213 frost-free days, leaving hyssop about 33 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"). Hyssop's 180-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Where in Oregon Fits Best
Even within Oregon's zones 5a-10a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for hyssop (USDA PHZM 2023):
Pollinator + Wildlife Value
Hyssop 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, hyssop can only work that bloom inside Oregon's frost window — roughly 213 days, opening after the last 28°F freeze (Feb 25 - Apr 26) and closing at the first (Oct 19 - Nov 26), per NOAA Regional Climate Centers ACIS, 1991-2020.
Oregon Cooperative Extension
For Oregon-specific cultivar recommendations, planting calendars, and pest pressure for hyssop, the canonical source is OSU Extension Service. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Hyssop native to Oregon?
No — the USDA PLANTS Database lists Hyssop as introduced rather than native in the Lower 48, so it is not part of Oregon's native flora. It grows here as a garden plant; pairing it with a few Oregon natives keeps local pollinators fed too.
Looking for plants that belong here? The Oregon 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 Hyssop in Oregon
When can I plant Hyssop in Oregon?
Oregon's last spring hard freeze (28°F) clears between Feb 25 and Apr 26, and the first fall hard freeze lands between Oct 19 and Nov 26 (NOAA Regional Climate Centers ACIS, 1991-2020). Hyssop is a long-lived planting, so target spring just after your local last hard freeze — or early fall while the soil holds warmth — and let it establish through the season.
What hardiness zone is Hyssop grown in across Oregon?
Oregon spans USDA hardiness zones 5a-10a (USDA ARS PHZM 2023). Hyssop carries a range of zones 3-9, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Oregon site have?
A typical Oregon site sees ~213 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Hyssop needs 180+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Hyssop native to Oregon?
No — the USDA PLANTS Database lists Hyssop as introduced rather than native in the Lower 48, so it is not part of Oregon's native flora. It grows here as a garden plant; pairing it with a few Oregon natives keeps local pollinators fed too.
How should I amend the soil for Hyssop in Oregon?
Hyssop tolerates pH 5.5-8.5 and well (dry spells), excessive (dry/moderately dry) drainage (FAO ECOCROP). That is a 3-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Oregon site — amend for drainage and organic matter first.
Will Hyssop actually grow on my specific land in Oregon?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores hyssop 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 Oregon
State-level data is a sketch. Your Growable Ground report scores hyssop against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Oregon hyssop averages can't show:
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