Unlikely — Zone Mismatch
Surinam grass (zones 10-13) does not overlap with Utah's zone range (4a-9a). Growing outdoors is unlikely without significant protection.
One zone short — what would close it
Surinam Grass is hardy to zone 10, and the warmest ground in Utah is zone 9 — 1 zone short. Planted in open ground it will not survive a Utah winter. To grow it here, grow surinam grass in a container and move it under cover for the coldest weeks, or give it a greenhouse.
Season extension and overwintering under cover both work at this margin. How to buy the weeks →
Zone math from 10-13 (plant) against 4-9 (Utah). 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.
Utah spans zones 4a-9a, but your yard has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score surinam grass against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Zone Comparison
Surinam Grass Needs
- USDA Zones: 10-13
- Frost-Free Days: 90+
- Sun: Full Sun
- Mature size: 2 ft tall
- Drought tolerance: Medium
Utah Has
- USDA Zones: 4a-9a
- Last Hard Freeze (28°F): Apr 12 - May 6
- First Hard Freeze (28°F): Oct 8 - Oct 27
- Annual Rainfall: 5-20 inches
- Common Soils: Sandy loam, Alkaline clay, Desert sand
Plant Zone Range (zones 10-13)
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 Surinam Grass in Utah
The frost window
Across Utah, the last spring hard freeze (28°F) clears between Apr 12 and May 6, and the first fall hard freeze lands between Oct 8 and Oct 27 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 155-day window you can count on — up to 198 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
Surinam Grass is frost-tender — its listed minimum temperature is 66.2°F (USDA PLANTS Database) — 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.
When to start the seed
Surinam Grass is direct-sown where it grows rather than started under cover, so there is no seed-tray head start to bank — Utah's dates above are the whole calendar for it. That makes the last-freeze date the binding constraint, and a warmer pocket of your own yard is worth more to this crop than it is to a transplanted one.
Days to maturity vs. the window
At 90 days to maturity (USDA PLANTS Database), counting from the last hard freeze it ripens with 65 days to spare even in Utah's tightest freeze scenario — room for a later start or a second sowing.
Timing tuned to sub-state frost dates — Summit 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 surinam grass does not survive a Utah 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 Utah under protection.
Frost-free days
Surinam Grass wants 90+ frost-free days; a typical Utah site sees ~175 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Surinam Grass needs ~3000 GDD (base 50°F) to ripen. The state median runs ~2690 GDD (from PRISM 1991-2020 climate normals), so Utah's typical season runs short on heat — pick a south-facing site and consider season extension.
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
Surinam Grass likes near-neutral soil (pH 4.5-6.5). That's the common-ground band across Utah's sandy loam and alkaline clay — 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 Utah soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Utah site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
Utah soil pH runs about 7.6–8.2, and that sits above surinam grass's tolerated 4.5–6.5, so the typical Utah parcel needs sulfur to bring it down. SSURGO maps it swinging by full points parcel to parcel, so your map unit, not the state number, decides whether surinam grass needs lime or sulfur.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. Utah soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Surinam Grass in Utah — Quick Answer
- Verdict: Unlikely — Zone Mismatch
- Plant Zones: 10-13 (USDA PLANTS Database)
- State Zones: 4a-9a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Apr 12 - May 6 to Oct 8 - Oct 27 (NOAA Regional Climate Centers ACIS, 1991-2020)
- Days to Maturity: 90 days
What Else to Consider for Surinam Grass in Utah
Zone compatibility tells you about winter cold survival — but Utah growers also need to think about:
Very low rainfall — irrigation essential
Alkaline soils (pH 7.5-8.5) limit many species
High altitude frost risk in mountain valleys
Growing surinam grass here specifically
Surinam Grass does best acidic (pH 4.5–6.5); Utah soils average near pH 7.9, alkaline enough to yellow its leaves as micronutrients lock away.
Work in elemental sulfur or acidic organic matter to pull your parcel toward pH 4.5–6.5, then retest. How to handle it →
What to actually do about these — and the constraints that apply to every Utah grower, not just surinam grass — is covered on the Utah growing guide.
Timing shifts within Utah
Utah isn't one climate. In Summit County, the last hard freeze (28°F) holds until about Jun 10 — roughly 45 days later than the recorded state median — so plant surinam grass to your county's window, not the statewide date.
Surinam Grass needs about 90 days of frost-free season to complete its cycle. Even Summit County — Utah’s shortest season at 98 frost-free days — clears that by 8 days, so season length isn’t the constraint anywhere in Utah. What varies is your own parcel.
Across Utah’s 29 counties the frost-free season runs from 98 days in Summit County to 237 days in Washington County — a spread of 139 days, which is why a single statewide planting date misleads. The median Utah county sees 175 frost-free days, leaving surinam grass about 85 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"). Surinam Grass's 90-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Utah Cooperative Extension
For Utah-specific cultivar recommendations, planting calendars, and pest pressure for surinam grass, the canonical source is Utah State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Common Questions About Growing Surinam Grass in Utah
When can I plant Surinam Grass in Utah?
Utah's last spring hard freeze (28°F) clears between Apr 12 and May 6, and the first fall hard freeze lands between Oct 8 and Oct 27 (NOAA Regional Climate Centers ACIS, 1991-2020). Surinam Grass is frost-tender — its listed minimum temperature is 66.2°F (USDA PLANTS Database) — so wait two to three weeks past your site's last hard freeze, when light frost has also stopped, before planting out.
Can Surinam Grass mature before first frost in Utah?
Yes — Surinam Grass matures in 90 days (USDA PLANTS Database), and Utah's dependable hard-freeze-free window runs 155 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 65 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 Surinam Grass grown in across Utah?
Utah spans USDA hardiness zones 4a-9a (USDA ARS PHZM 2023). Surinam Grass carries a range of zones 10-13, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Utah site have?
A typical Utah site sees ~175 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Surinam Grass needs 90+ 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 Summit, the freeze-free season runs shorter than the state average, so verify your own county's window.
How should I amend the soil for Surinam Grass in Utah?
Surinam Grass prefers pH 4.5-6.5 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Utah soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Surinam Grass actually grow on my specific land in Utah?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores surinam grass 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 Utah
State-level data is a sketch. Your Growable Ground report scores surinam grass against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Utah surinam grass averages can't show:
We read public map data around Utah — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Utah surinam grass average
Explore More
Growing guides for surinam grass
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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