Lawn Care Guide for Big Horn County
Big Horn County, Wyoming
USDA SSURGO / PHZMThis week in Big Horn County · next up in 6 days (Aug 3)
Get ready to seed cool-season grass — the best fall window is about to open.
Data Story
About Lawn Care in Big Horn County, Wyoming
Tough Conditions in the Big Horn Basin
With a lawn difficulty score of 29.6, Big Horn County is one of the more challenging places in Wyoming to grow grass. This score sits well below the national median of 50.0, largely due to the desert-like precipitation levels in hardiness zone 5a.
High Heat and Desert Aridity
The county averages just 7.1 inches of rain annually, a fraction of the 30 inches needed for healthy lawns. While 41 extreme heat days push grass to its limits, the 2479 growing degree days offer enough warmth for growth if you can supply the necessary irrigation.
Foundational Prep is Essential
Comprehensive soil data is unavailable for this region, making a professional soil test your first step for success. Arid soils in the Basin are often alkaline, so focus on adding organic compost to improve water retention and balance the pH levels.
Managing 35 Weeks of Drought
The county experienced 35 weeks of drought over the past year, and the entire area remains abnormally dry. Effective water conservation involves mulching your lawn clippings to keep the soil surface cool and moist during those 41 scorching summer days.
Targeting Success in Zone 5a
Hardy cool-season grasses like Crested Wheatgrass are excellent choices for this climate's extreme dry spells. Aim to complete your seeding projects shortly after the last frost on May 9th to take advantage of the early summer growing window.
Lawn Difficulty Score
Top Grass Fit for Big Horn County
Cool-season grasses are the general fit here
County soil and zone data are incomplete, so we show a category recommendation rather than a precise cultivar score for Big Horn County.
Why we ruled these out
- Scotts Turf Builder Bermudagrass — USDA zone 5a is below Scotts Turf Builder Bermudagrass's effective range (6–11); not recommended for this county.
See our fit-score methodology for how survivability is determined.
Recommended Grasses
Buffalograss
Bouteloua dactyloides
Blue Grama
Bouteloua gracilis
Tall Fescue
Festuca arundinacea
Choosing grass in Big Horn County
Severe drought (35 wk in drought / yr) and short growing season (143-day window) are the two things working hardest against a lawn in Big Horn County. Here's how to choose for both — then the specific pick.
- Drought-tolerant grass seedWhat survives where water is scarce and often restricted.
- Germinating fast in a short windowPre-germination and priming when the season is tight.
- Tall Fescue, explainedTraits, care, and where Tall Fescue wins — the species behind your top match.
Top match for Big Horn County: Tall Fescue
See the full breakdownPremium Grass Seeds is a sister site in our network. We may earn a commission from qualifying purchases made through its retailer links — this never affects your price. Guidance here reflects your county’s climate and soil data, not hands-on testing.
Climate Snapshot
Annual Precip
7.1"
Growing Degree Days
2,479.371
Base 50F
Last Spring Frost
05/09
First Fall Frost
09/29
Days Above 95F
41
Hardiness Zone
5a
Seeding Calendar — Big Horn County
Personalized to this county’s frost dates — a 143-day growing season. Windows below are computed from local last-spring and first-fall frost normals, so they differ county-to-county even within USDA Zone 5A.
Plan your seeding — Big Horn County
Pick a grass and a goal to get a personalized schedule anchored to this county’s frost dates.
- 1Prepare the seedbedMay 8 – May 21
Mow low, dethatch or rake, and loosen the top ½ inch of soil so seed makes good contact.
- 2Sow seedMay 22 – Jun 19
Best window to sow Buffalograss in Big Horn County, anchored to your local frost dates.
- 3EstablishJun 20 – Jul 17
Protect young seedlings: mow only after they reach ~3 inches and hold off on weed pre-emergents until established.
Keep the seedbed consistently moist — roughly ¼ inch of water daily, split into shorter cycles if the surface dries out quickly. County-specific soil texture isn’t available here, so adjust to how fast your own soil drains.
Seasonal Lawn Care Checklist
Spring
- Apply pre-emergent herbicide when soil reaches 55F
- Overseed bare spots once frost risk passes
- Start irrigation if rainfall is below 1 inch/week
- Soil test every 2-3 years — adjust lime or sulfur as needed
Summer
- Mow at recommended height weekly
- Water deeply 1-2 times per week (1 inch total)
- Avoid fertilizing cool-season grasses in peak heat
- Scout for grubs and treat if >10 per sq ft
Fall
- Core aerate compacted areas
- Apply fall fertilizer (highest N application for cool-season)
- Continue mowing until growth stops
- Rake or mulch leaves to prevent smothering
Winter
- Avoid walking on frozen turf
- Service mower and sharpen blades
- Plan spring soil amendments based on fall test
- Keep lawn clear of debris
Watering Deficit Calculator
Monthly Deficit
3.2"
inches of water
Monthly Water
9,969
gallons
Estimated Monthly Cost
$79.75
at $0.008/gallon average
Estimates based on 7" annual precipitation and estimated evapotranspiration. Actual costs vary by local water rates.
Common Lawn Problems in Big Horn County
Drought Stress
With only 7 inches of annual rainfall, lawns in Big Horn County face significant drought stress. Consider drought-tolerant grass species and deep, infrequent watering.
Persistent Drought Conditions
Big Horn County experienced drought conditions for 35 of the past 52 weeks. Prioritize water-efficient grasses and consider reducing lawn area.
Learn more about regional lawn challenges at The Lawn Report.
Lawn Care Advisory: Big Horn County
Lawn Verdict
Big Horn County sits in USDA hardiness zone 5a, a transitional zone where cool-season grasses dominate but some warm-season varieties can survive. with winter lows reaching around -20.0°F. though only 2,479.371 growing degree days favor cool-season varieties like Kentucky bluegrass and fescue. Low rainfall (7.1 inches) means supplemental irrigation is essential during summer months.
Seasonal Breakdown
Wait until after May 9 to seed or overseed; soil temperatures should consistently reach 50-55°F. Cool summers (July averages 73.0°F) reduce heat stress — maintain regular mowing and moderate watering. With 40.81428571428571 days above 90°F annually, warm-season grasses recover faster from summer stress than cool-season types. Aerate and overseed cool-season lawns by early fall, well before September 29; this is the best renovation window. Winters are harsh (January averages 18.7°F); avoid foot traffic on frozen turf and plan snow mold prevention.
Watering Guidance
Low annual precipitation (7.1 inches) makes irrigation essential for maintaining green turf through summer. Currently, 100.0% of the county is in moderate drought according to the US Drought Monitor. Consider reducing irrigation frequency and allowing cool-season lawns to go semi-dormant during peak heat. Cool summers reduce water demand; overwatering is a bigger risk than drought stress.
Regional Context
Big Horn County is close to the Wyoming average temperature, it is somewhat drier than the state average, the growing season is noticeably longer than the state average, USDA zone 5a helps guide grass selection compared to neighboring counties.
Want detailed soil composition, drainage classes, and soil series data? View soil details on SoilByCounty.com
Frequently Asked Questions
What USDA hardiness zone is Big Horn County in?
What is the best grass for Big Horn County?
How long is the growing season in Big Horn County?
How much rainfall does Big Horn County get?
Data sourced from USDA SSURGO, NOAA Climate Normals (1991-2020), USDA Plant Hardiness Zone Map, and US Drought Monitor. Lawn difficulty scores and grass recommendations are estimates for informational purposes only.
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