Yes — Strong Match
shiso is grown as an annual, so season length decides it here, not a winter zone — and Oregon's typical season runs ~213 frost-free days against the ~80 shiso needs.
Sow by about Aug 28
Shiso 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 Oregon season runs ~213 frost-free days, leaving 133 days of slack. That is room to sow as late as about Aug 28 and still finish before the usual first freeze (Nov 6).
Want more weeks at either end of that window? How to buy the weeks →
80 frost-free days required against Oregon’s ~213-day season. NOAA Regional Climate Centers ACIS 1991-2020 (28°F killing freeze), state median across counties, via stateClimateData.ts.
Your yard isn't the whole zone.
Shiso is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Oregon site runs ~213 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 shiso against your land's actual frost dates, sun, and soil.
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Zone Comparison
Shiso Needs
- USDA Zones: Data pending
- Frost-Free Days: 80+
- Sun: Full Sun
- Mature size: 2 ft tall
- Picking window: ~60 days of harvest
- Drought tolerance: High
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
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 Shiso 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 shiso goes out, not when it starts. It is sown under cover about 4 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.
Days to maturity vs. the window
At 70 days to maturity (USDA PLANTS Database), counting from the last hard freeze it ripens with 106 days to spare even in Oregon's tightest freeze scenario — room for a later start or a second sowing.
Timing tuned to sub-state frost dates — Klamath County, not the statewide average.
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
Frost-free days
Shiso wants 80+ frost-free days; a typical Oregon site sees ~213 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Shiso needs ~1400 GDD (base 50°F) to ripen. The state median runs ~1666 GDD (from PRISM 1991-2020 climate normals), so Oregon 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
Shiso likes near-neutral soil (pH 5.5-7.5). That's the common-ground band across Oregon's volcanic and silt loam (willamette) — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 5.5 and 6 — 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). If your Oregon site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
Oregon's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel. Shiso 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 shiso performs.
Check your parcel → Source: USDA NRCS SSURGO.
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.
Shiso in Oregon — Quick Answer
- Verdict: Yes — Strong Match
- Plant Zones: Data pending (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: 70 days
What Else to Consider for Shiso 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)
Growing shiso here specifically
Oregon's soils run mostly silt loam (Mollisols), and whether that suits shiso's pH 5.5–7.5 preference comes down to your exact parcel, not the statewide picture.
Pull your parcel's SSURGO map unit, test pH, and amend toward shiso's 5.5–7.5 target before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Oregon grower, not just shiso — is covered on the Oregon growing guide.
Timing shifts within Oregon
Oregon isn't one climate. In Klamath County, the last hard freeze (28°F) holds until about Jun 9 — roughly 67 days later than the recorded state median — so plant shiso to your county's window, not the statewide date.
Shiso needs about 80 days of frost-free season to complete its cycle. Even Klamath County — Oregon’s shortest season at 86 frost-free days — clears that by 6 days, so season length isn’t the constraint anywhere in Oregon. What varies is your own parcel.
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 shiso about 133 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"). Shiso'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
Shiso draws honeybees (low value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, shiso 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.
Good to Know Before You Plant Shiso
Shiso is listed as toxic to dogs, cats (all) at a mild level (Cornell). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear. Worth knowing for placement: in Oregon this is a one-season plant and the first hard freeze (Oct 19 - Nov 26) takes it down, so the exposure above is a summer-long one rather than something standing in the bed all year.
Recommended Shiso Varieties for Oregon
Oregon publishes no state variety trial for shiso, so we won't invent a "best for Oregon" list. Choose types rated to your USDA hardiness zone (5a-10a), and confirm winter survival and drainage against your own parcel.
Oregon Cooperative Extension
For Oregon-specific cultivar recommendations, planting calendars, and pest pressure for shiso, the canonical source is OSU Extension Service. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Shiso native to Oregon?
No — the USDA PLANTS Database lists Shiso 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 Shiso in Oregon
When can I plant Shiso 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). 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 Shiso mature before first frost in Oregon?
Yes — Shiso matures in 70 days (USDA PLANTS Database), and Oregon's dependable hard-freeze-free window runs 176 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 106 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 Shiso grown in across Oregon?
Oregon spans USDA hardiness zones 5a-10a (USDA ARS PHZM 2023). Shiso carries a range of zones Data pending, 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). Shiso 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 Klamath, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Shiso native to Oregon?
No — the USDA PLANTS Database lists Shiso 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 Shiso in Oregon?
Shiso prefers pH 5.5-7.5 and well (dry spells) drainage (Growable Ground Plant Database). That sits in the common-ground band across Oregon soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Shiso actually grow on my specific land in Oregon?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores shiso 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 shiso against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Oregon shiso averages can't show:
We read public map data around Oregon — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Oregon shiso average
Explore More
Growing guides for shiso
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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