shiso (Perilla frutescens), photographi

Can I Grow Shiso in Wyoming?

USDA Zones 3b-6a · Plant zone range Data pending

Yes — Strong Match

shiso is grown as an annual, so season length decides it here, not a winter zone — and Wyoming's typical season runs ~151 frost-free days against the ~80 shiso needs.

Sow by about Jul 26

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 Wyoming season runs ~151 frost-free days, leaving 71 days of slack. That is room to sow as late as about Jul 26 and still finish before the usual first freeze (Oct 4).

Want more weeks at either end of that window? How to buy the weeks →

80 frost-free days required against Wyoming’s ~151-day season. NOAA Regional Climate Centers ACIS 1991-2020 (28°F killing freeze), state median across counties, via stateClimateData.ts.

Shiso in Wyoming — the short answer

Shiso in Wyoming: full sun, against a state median of ~151 frost-free days.

Wyoming zones
3b-6a
USDA PHZM 2023
Frost window
May 4 - May 13 – Sep 30 - Oct 7
NOAA RCC ACIS 1991-2020, 28°F
Shortest county season
79 days
NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
Days to maturity
70 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.

Score your parcel · free to start

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 Wyoming site runs ~151 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.

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

Wyoming is not one climate

A single Wyoming answer averages 23 counties whose growing seasons are 87 days apart — from 79 frost-free days in Teton County to 166 in Big Horn County. Which end of that your land sits nearer changes what shiso can finish before the first hard freeze.

79 daysTeton County166 daysBig Horn County

The middle half of 23 counties runs 136–155 days, with a median of 151 days — a 87-day span end to end.

Measured across 23 Wyoming 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.

Zone Comparison

Shiso Needs

  • USDA Zones: Data pending
  • Frost-Free Days: 80+
  • Sun: Full Sun
  • Mature size: 2 ft tallWe haven't confirmed this against a published source yet.
  • Picking window: ~60 days of harvestWe haven't confirmed this against a published source yet.
  • Drought tolerance: HighWe haven't confirmed this against a published source yet.

Wyoming Has

  • USDA Zones: 3b-6a
  • Last Hard Freeze (28°F): May 4 - May 13
  • First Hard Freeze (28°F): Sep 30 - Oct 7
  • Annual Rainfall: 6-20 inches
  • Common Soils: Sandy loam, Clay, Alkaline

Preferred Soil pH

3.5 (Acidic)7.0 (Neutral)9.0 (Alkaline)
Highlighted range: pH 5.5 – 7.5

We haven't confirmed this against a published source yet.

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 Shiso in Wyoming

The frost window

Across Wyoming, the last spring hard freeze (28°F) clears between May 4 and May 13, and the first fall hard freeze lands between Sep 30 and Oct 7 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 140-day window you can count on — up to 156 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

Shiso is frost-tender — its killing temperature is 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. We haven't confirmed this against a published source yet.

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 Wyoming's late-side last freeze of May 13 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 (Growable Ground Plant Database), counting from the last hard freeze it ripens with 70 days to spare even in Wyoming's tightest freeze scenario — room for a later start or a second sowing.

Timing tuned to sub-state frost dates — Teton 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

Frost-free days

Shiso wants 80+ frost-free days; a typical Wyoming site sees ~151 (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. We haven't confirmed this against a published source yet. The state median runs ~1866 GDD (from PRISM 1991-2020 climate normals), so Wyoming'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

Shiso likes near-neutral soil (pH 5.5-7.5). That's the common-ground band across Wyoming's sandy loam and clay — 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 Wyoming soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Wyoming site is heavier clay or sits in a low spot, a raised bed lifts the roots above wet ground, or work in compost. pH range and preferred pH: We haven't confirmed this against a published source yet.

Your land, not the state average

Wyoming's soils run mostly 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 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. Wyoming soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.

Before you plant shiso for food

Anything you grow to eat takes up what is in the ground it grows in, so what is on record near you is worth knowing before shiso goes in. What follows is Wyoming’s documented federal record at state scale — a screening signal, not a soil test, and not a statement about any one lot.

Safe to Grow Here?

What the federal record shows across Wyoming — and how to grow with it.

Federal record: High

We checked the federal record across Wyoming — 4,526 documented sites across 7 of the 8 source types we track.

The most significant on record: 64 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.

Wyoming carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds of imported, lab-tested soil grow well almost anywhere in the meantime.

Know before you grow — the guide

Sources Checked

across Wyoming

Severity Distribution

across Wyoming

High42Moderate1,188Low3,296

Highest-Severity Sites

Mining Sites · Past Producer
Superfund · Superfund NPL
PFAS Sampling · PFAS Detected
Mining Sites · Past Producer
Mining Sites · Past Producer

Know Before You Grow

  • •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
  • •Mine waste leaches heavy metals. Test for lead, arsenic and cadmium before growing food here.
  • •TRI facilities report what they release. Check the wind — downwind beds catch more of it.

Sources: EPA, USGS — 950K documented sites tracked nationwide across 8 federal source types.

What Else to Consider for Shiso in Wyoming

The zone range tells you where shiso is grown — but Wyoming growers also need to think about:

Extremely short growing season (60-90 frost-free days)

Very low rainfall requires irrigation

Persistent high winds desiccate and damage plants

Growing shiso here specifically

Shiso prefers pH 5.5–7.5 and room to root medium; across much of Wyoming, restrictive group-D subsoil (SSURGO) blocks that depth.

Build shiso a deep raised bed of loose soil to bypass the dense subsoil entirely. How to handle it →

What to actually do about these — and the constraints that apply to every Wyoming grower, not just shiso — is covered on the Wyoming growing guide.

Timing shifts within Wyoming

Wyoming isn't one climate. In Teton County, the last hard freeze (28°F) holds until about Jun 16 — roughly 41 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. 22 of Wyoming’s 23 counties give it that outright. The tightest that does is Sublette County at 89 frost-free days — 9 to spare. Below that line you are transplanting or extending the season, not direct-sowing.

Across Wyoming’s 23 counties the frost-free season runs from 79 days in Teton County to 166 days in Big Horn County — a spread of 87 days, which is why a single statewide planting date misleads. The median Wyoming county sees 151 frost-free days, leaving shiso about 71 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). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, shiso can only work that bloom inside Wyoming's frost window — roughly 151 days, opening after the last 28°F freeze (May 4 - May 13) and closing at the first (Sep 30 - Oct 7), per NOAA Regional Climate Centers ACIS, 1991-2020. Pollinator value: We haven't confirmed this against a published source yet.

Good to Know Before You Plant Shiso

Shiso is listed as toxic to dogs, cats (all) at a mild level. (Source: Cornell Poisonous Plants Database.) Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear. Worth knowing for placement: in Wyoming this is a one-season plant and the first hard freeze (Sep 30 - Oct 7) 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 Wyoming

Wyoming publishes no state variety trial for shiso, so we won't invent a "best for Wyoming" list. Choose types rated to your USDA hardiness zone (3b-6a), and confirm winter survival and drainage against your own parcel.

Wyoming Cooperative Extension

For Wyoming-specific cultivar recommendations, planting calendars, and pest pressure for shiso, the canonical source is University of Wyoming Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.

Is Shiso native to Wyoming?

No — the USDA PLANTS Database lists Shiso as introduced rather than native in the Lower 48, so it is not part of Wyoming's native flora. It grows here as a garden plant; pairing it with a few Wyoming natives keeps local pollinators fed too.

Looking for plants that belong here? The Wyoming growing guide lists plants that USDA PLANTS records growing in Wyoming 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 Shiso in Wyoming

When can I plant Shiso in Wyoming?

Wyoming's last spring hard freeze (28°F) clears between May 4 and May 13, and the first fall hard freeze lands between Sep 30 and Oct 7 (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 Wyoming?

Yes — Shiso matures in 70 days (Growable Ground Plant Database), and Wyoming's dependable hard-freeze-free window runs 140 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 70 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 Wyoming?

Wyoming spans USDA hardiness zones 3b-6a (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 Wyoming site have?

A typical Wyoming site sees ~151 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 Teton, the freeze-free season runs shorter than the state average, so verify your own county's window.

Is Shiso native to Wyoming?

No — the USDA PLANTS Database lists Shiso as introduced rather than native in the Lower 48, so it is not part of Wyoming's native flora. It grows here as a garden plant; pairing it with a few Wyoming natives keeps local pollinators fed too.

How should I amend the soil for Shiso in Wyoming?

Shiso prefers pH 5.5-7.5 and well (dry spells) drainage. We haven't confirmed this against a published source yet. That sits in the common-ground band across Wyoming 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 Wyoming?

State-level zone + climate data is a sketch. A Growable Ground parcel report scores shiso against your address's mapped soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.

Free to start

Check your specific parcel in Wyoming

State-level data is a sketch. Your Growable Ground report scores shiso against your land's mapped soil, modelled sun, drainage, and frost data — not zone averages.

Three things about your lot that Wyoming shiso averages can't show:

Your soil pHYour frost-free days — Wyoming averages 151Your sun & shade

We read public map data around Wyoming — soil, climate, flood, and parcel records. How we handle your address.

25+ data sources read at your address, not the Wyoming shiso average

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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