Conditional — Some Areas
spear grass (zones 9-13) reaches only part of Utah (4a-9a): zone 9 are in range, so where you are in the state decides it.
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 spear grass against your land's actual soil, sun, and frost.
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Zone Comparison
Spear Grass Needs
- USDA Zones: 9-13
- Frost-Free Days: 120+
- Sun: Full Sun
- Mature size: 8 in tall
- Drought tolerance: High
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 9-13)
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 Spear 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
Spear Grass is frost-tender — its listed minimum temperature is 68°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
Spear 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.
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 spear grass survives winter in part of Utah, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Spear Grass wants 120+ frost-free days; a typical Utah site sees ~175 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves a workable window — start indoors to bank time.
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
Spear Grass tolerates a wide pH range (pH 4.5-8.5) — 4 units, acid ground through alkaline — so soil acidity is rarely what limits it in Utah. 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 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.
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.
Spear Grass in Utah — Quick Answer
- Verdict: Conditional — Some Areas
- Plant Zones: 9-13 (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)
What Else to Consider for Spear 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
What to actually do about these — and the constraints that apply to every Utah grower, not just spear grass — is covered on the Utah growing guide.
Timing shifts within Utah
Spear Grass needs about 120 days of frost-free season to complete its cycle. 26 of Utah’s 29 counties give it that outright. The tightest that does is Sevier County at 136 frost-free days — 16 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
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 spear grass about 55 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"). Spear Grass's 120-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 spear grass, the canonical source is Utah State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Spear Grass native to Utah?
Spear Grass is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in Utah. It can still earn a place in a Utah garden — the zone comparison above tells you whether it will thrive.
Looking for plants that belong here? The Utah 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 Spear Grass in Utah
When can I plant Spear 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). Spear Grass is frost-tender — its listed minimum temperature is 68°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.
What hardiness zone is Spear Grass grown in across Utah?
Utah spans USDA hardiness zones 4a-9a (USDA ARS PHZM 2023). Spear Grass carries a range of zones 9-13, 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). Spear Grass needs 120+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Spear Grass native to Utah?
Spear Grass is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in Utah. It can still earn a place in a Utah garden — the zone comparison above tells you whether it will thrive.
How should I amend the soil for Spear Grass in Utah?
Spear Grass tolerates pH 4.5-8.5 and well (dry spells) drainage (FAO ECOCROP). That is a 4-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Utah site — amend for drainage and organic matter first.
Will Spear Grass actually grow on my specific land in Utah?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores spear 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 spear grass against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Utah spear grass averages can't show:
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