Unlikely — Zone Mismatch
skimmia (zones 7-8) does not overlap with Iowa's zone range (4b-6a). Growing outdoors is unlikely without significant protection.
One zone short — what would close it
Skimmia is hardy to zone 7, and the warmest ground in Iowa is zone 6 — 1 zone short. Planted in open ground it will not survive a Iowa winter. To grow it here, grow skimmia in a hoop house or unheated greenhouse — its modeled 1.5-zone lift covers this gap.
A hoop house or unheated greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 7-8 (plant) against 4-6 (Iowa). Lift modeled by crop_engine.GREENHOUSE_ZONE_MODIFIER_BY_SUBTYPE['hoop_house'] (+1.5 zones) via api/fast_sections.py Unlock Engine v2.
Skimmia in Iowa — the short answer
Skimmia in Iowa: hardy in zones 7–8, shade.
- Plant zones
- 7-8
- Rated hardy to zone 7a by NC State Extension Gardener Plant Toolbox, checked Oct 2026. Ceiling: not verified.
- Iowa zones
- 4b-6a
- USDA PHZM 2023
- Frost window
- Apr 10 - Apr 17 – Oct 18 - Oct 23
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 168 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
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.
Iowa spans zones 4b-6a, 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 skimmia against your parcel's actual hardiness, soil, and sun.
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
Iowa is not one climate
Iowa’s winter-low ladder runs across 99 counties, from zone 4.5 in Clayton County to zone 6 in Lee County. That is 15°F between the two counties’ average coldest night — the difference between skimmia overwintering in the ground and coming under cover.
The middle half of 99 counties runs 5–5.5 zones, with a median of 5 zones — a 1.5-zone span end to end.
Measured across 99 Iowa counties. USDA PHZM 2023, per county. 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 Skimmia Stands in Iowa
Skimmia is rated for zones 7–8 — a cold floor USDA puts at 0 to 10°F. No Iowa county sits inside it, so in open ground this is a grown-under-cover plant here rather than a bed plant — which is a statement about Iowa winters, not about skimmia.
Below the zone 7 floor
99 counties
- Clayton County · zone 4b
- Howard County · zone 4b
- Winneshiek County · zone 4b
3 of 99 shown
Winter cold is the limit here — the same plant works in a container that comes under cover.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. A zone is a 10°F band of average annual extreme minimum temperature, so the floor above is the band the plant's rating denotes, not a single measured kill point. Slope, shelter and cold-air drainage routinely move a site half a zone either way from its county figure — which is the part only your address resolves.
Zone Comparison
Skimmia Needs
- USDA Zones: 7-8
- Sun: ShadeWe haven't confirmed this against a published source yet.
- Mature size: 5 ft tallWe haven't confirmed this against a published source yet.
- Drought tolerance: LowWe haven't confirmed this against a published source yet.
Iowa Has
- USDA Zones: 4b-6a
- Last Hard Freeze (28°F): Apr 10 - Apr 17
- First Hard Freeze (28°F): Oct 18 - Oct 23
- Annual Rainfall: 26-36 inches
- Common Soils: Prairie loess, Silt loam, Clay loam
Plant Zone Range (zones 7-8)
Preferred Soil pH
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 Skimmia in Iowa
The frost window
Across Iowa, the last spring hard freeze (28°F) clears between Apr 10 and Apr 17, and the first fall hard freeze lands between Oct 18 and Oct 23 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 184-day window you can count on — up to 196 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.
Winter standing
Iowa runs as cold as USDA zone 4, and no sourced winter-hardiness floor is on record for skimmia, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether skimmia is a permanent planting or a replant-every-spring crop for you turns on your own zone within Iowa; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Howard 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.
Soil + Drainage Fit
Skimmia likes near-neutral soil (pH 4.5-6.5). That's the common-ground band across Iowa's prairie loess and silt loam — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 5 and 6 — worth knowing before you decide whether a Iowa soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Iowa 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
Iowa's soils run mostly silty clay loam, but SSURGO maps the series, texture, and drainage under your exact parcel. What matters for skimmia is the horizon its roots actually work, not the surface. That map unit, not the state average, decides how skimmia 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. Iowa soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Skimmia in Iowa
Zone compatibility tells you about winter cold survival — but Iowa growers also need to think about:
Cold winters reaching -20F or below
Variable spring weather delays planting
Wind exposure on open prairies desiccates plants
Growing skimmia here specifically
Iowa's soils run mostly silty clay loam (Mollisols), and whether that suits skimmia's pH 4.5–6.5 preference comes down to your exact parcel, not the statewide picture.
Pull your parcel's SSURGO map unit, test pH, and amend toward skimmia's 4.5–6.5 target before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Iowa grower, not just skimmia — is covered on the Iowa growing guide.
Timing shifts within Iowa
Iowa isn't one climate. In Howard County, the last hard freeze (28°F) holds until about Apr 24 — roughly 10 days later than the recorded state median — so plant skimmia to your county's window, not the statewide date.
County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). A parcel report resolves your address's own frost dates.
Where in Iowa Skimmia Is Zone-Hardy
Skimmia is rated for USDA zones 7–8. No Iowa county reaches it. Even Lee County, the state’s mildest winter at zone 6a, sits below the plant’s zone 7 floor — so in open ground this one needs winter protection here, or a container that comes under cover.
Across those 99 counties Iowa’s winter-low ladder runs from zone 4b in Clayton County to zone 6a in Lee County — 1.5 USDA zones of spread, which is 15°F between the two counties’ average coldest night of the year. None of that range reaches the band skimmia needs, so here the statewide answer really is the answer.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. Skimmia’s zone 7–8 band: Rated hardy to zone 7a by NC State Extension Gardener Plant Toolbox, checked Oct 2026. Ceiling: not verified.. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Skimmia draws honeybees (moderate value). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, skimmia can only work that bloom inside Iowa's frost window — roughly 189 days, opening after the last 28°F freeze (Apr 10 - Apr 17) and closing at the first (Oct 18 - Oct 23), 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 Skimmia
Skimmia is listed as toxic to dogs, cats (all) at a mild level. (Source: Pet Poison Helpline.) Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear.
Iowa Cooperative Extension
For Iowa-specific cultivar recommendations, planting calendars, and pest pressure for skimmia, the canonical source is Iowa State University Extension and Outreach. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Skimmia native to Iowa?
No — the USDA PLANTS Database lists Skimmia as introduced rather than native in the Lower 48, so it is not part of Iowa's native flora. It grows here as a garden plant; pairing it with a few Iowa natives keeps local pollinators fed too.
Looking for plants that belong here? The Iowa growing guide lists plants that USDA PLANTS records growing in Iowa 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 Skimmia in Iowa
When can I plant Skimmia in Iowa?
Iowa's last spring hard freeze (28°F) clears between Apr 10 and Apr 17, and the first fall hard freeze lands between Oct 18 and Oct 23 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Skimmia, so this page does not state whether it overwinters in Iowa and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Skimmia grown in across Iowa?
Iowa spans USDA hardiness zones 4b-6a (USDA ARS PHZM 2023). Skimmia is listed for zones 7-8, which do not overlap them, so there is no zone in Iowa where this page can call outdoor growing reliable. A parcel report resolves your own address's zone.
How many frost-free days does a typical Iowa site have?
A typical Iowa site sees ~189 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Skimmia needs 150+ 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 Howard, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Skimmia native to Iowa?
No — the USDA PLANTS Database lists Skimmia as introduced rather than native in the Lower 48, so it is not part of Iowa's native flora. It grows here as a garden plant; pairing it with a few Iowa natives keeps local pollinators fed too.
How should I amend the soil for Skimmia in Iowa?
Skimmia prefers pH 4.5-6.5 and well (dry spells) drainage. We haven't confirmed this against a published source yet. That sits in the common-ground band across Iowa soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Skimmia actually grow on my specific land in Iowa?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores skimmia 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 Iowa
State-level data is a sketch. Your Growable Ground report scores skimmia against your land's mapped soil, modelled sun, drainage, and frost data — not zone averages.
Three things about your lot that Iowa skimmia averages can't show:
We read public map data around Iowa — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Iowa skimmia average
Explore More
Growing guides for skimmia
Explore Iowa county by county
Iowa carries 99 counties with their own USDA zone — a sample of the growing pages for skimmia there:
Where else skimmia grows
Skimmia's zone band crosses state lines — these are the states closest to Iowa 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 Iowa
Iowa has a growing page for 810 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
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