Unlikely — Zone Mismatch
red river gum (Southern Provenances) (zones 8-11) does not overlap with Iowa's zone range (4b-6a). Growing outdoors is unlikely without significant protection.
2 zones short — what would close it
Red River Gum Southern Provenances is hardy to zone 8, and the warmest ground in Iowa is zone 6 — 2 zones short. Planted in open ground it will not survive a Iowa winter. To grow it here, grow red river gum southern provenances under glass — a greenhouse is the only lift this wide the engine models.
A greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 8-11 (plant) against 4-6 (Iowa). Lift modeled by crop_engine Sprint 20B effective_zone_modifier (+2 zones) via api/fast_sections.py Unlock Engine v2.
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 red river gum southern provenances against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Red River Gum Southern Provenances Needs
- USDA Zones: 8-11
- Frost-Free Days: 180+
- Sun: Full Sun
- Mature size: 120 ft tall
- Drought tolerance: Medium
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 8-11)
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 Red River Gum Southern Provenances 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 red river gum southern provenances, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether red river gum southern provenances 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: 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 red river gum southern provenances does not survive a Iowa winter in the ground. The season figures below measure a different question — whether it could finish a season here at all — and they only bear on Iowa under protection.
Frost-free days
Red River Gum Southern Provenances wants 180+ frost-free days; a typical Iowa site sees ~189 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves a tight window — use transplants and pick early-maturing cultivars.
Chill hours
Red River Gum Southern Provenances has no winter-chill requirement — its listed minimum is 0 hours (USDA PLANTS Database). Iowa typically banks ~2500 chill hours per winter (from PRISM 1991-2020 climate normals), so chill is not a constraint on this plant here — and not evidence in its favour either. Winter survival and season length are what decide it.
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
Red River Gum Southern Provenances tolerates a wide pH range (pH 4.5-8) — 3.5 units, acid ground through alkaline — so soil acidity is rarely what limits it in Iowa. 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 5 and 7 — worth knowing before you decide whether a Iowa soil test result is a problem or just a number. Drainage matters: this plant wants poorly (saturated >50% of year), well (dry spells). If your Iowa site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
SSURGO maps about 42.9% of Iowa as poorly or somewhat-poorly drained, and the class flips parcel to parcel. Red River Gum Southern Provenances sits mid-range for drought tolerance, so either extreme can cost you — your soil map unit, not the state average, is the real answer.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. Iowa soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Red River Gum Southern Provenances in Iowa — Quick Answer
- Verdict: Unlikely — Zone Mismatch
- Plant Zones: 8-11 (USDA PLANTS Database)
- State Zones: 4b-6a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Apr 10 - Apr 17 to Oct 18 - Oct 23 (NOAA Regional Climate Centers ACIS, 1991-2020)
What Else to Consider for Red River Gum Southern Provenances 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 red river gum southern provenances here specifically
Red River Gum Southern Provenances needs sharp drainage and sends deep roots hardy to about 44°F; in Iowa, about 42.9% of soils are poorly-drained (SSURGO), and standing water is what actually kills it.
Build red river gum southern provenances up on a coarse, free-draining mound so its crown never sit in saturated soil. How to handle it →
What to actually do about these — and the constraints that apply to every Iowa grower, not just red river gum southern provenances — 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 red river gum southern provenances to your county's window, not the statewide date.
Red River Gum Southern Provenances needs about 180 days of frost-free season to complete its cycle. 90 of Iowa’s 99 counties give it that outright. The tightest that does is Plymouth County at 180 frost-free days — 0 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
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"). Red River Gum Southern Provenances's 180-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
Red River Gum Southern Provenances draws honeybees and native bees (high value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, red river gum southern provenances 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.
Good to Know Before You Plant Red River Gum Southern Provenances
Red River Gum Southern Provenances is listed as toxic to dogs, cats (leaves) at a moderate level (ASPCA). 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 red river gum southern provenances, 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 Red River Gum Southern Provenances native to Iowa?
No — the USDA PLANTS Database lists Red River Gum Southern Provenances 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 USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Red River Gum Southern Provenances in Iowa
When can I plant Red River Gum Southern Provenances 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 Red River Gum Southern Provenances, 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 Red River Gum Southern Provenances grown in across Iowa?
Iowa spans USDA hardiness zones 4b-6a (USDA ARS PHZM 2023). Red River Gum Southern Provenances carries a range of zones 8-11, so the overlap zones are where outdoor growing is most reliable.
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). Red River Gum Southern Provenances needs 180+ 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 Red River Gum Southern Provenances native to Iowa?
No — the USDA PLANTS Database lists Red River Gum Southern Provenances 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 Red River Gum Southern Provenances in Iowa?
Red River Gum Southern Provenances tolerates pH 4.5-8 and poorly (saturated >50% of year), well (dry spells) drainage (FAO ECOCROP). That is a 3.5-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Iowa site — amend for drainage and organic matter first.
Will Red River Gum Southern Provenances actually grow on my specific land in Iowa?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores red river gum southern provenances 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 Iowa
State-level data is a sketch. Your Growable Ground report scores red river gum southern provenances against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Iowa red river gum southern provenances 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 red river gum southern provenances average
Explore More
Growing guides for red river gum southern provenances
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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