Lawn Care Guide for Union County
Union County, Illinois
Data Story
About Lawn Care in Union County, Illinois
Southern Heat Challenges Union Lawns
Union County presents a challenge for homeowners with a lawn difficulty score of 55.6, well below the state average of 69.8. This Zone 7a climate requires more active management to keep turf green through the long, warm summers.
High Rainfall Meets Intense Heat
The county sees 51.1 inches of rain annually, which is significantly higher than the Illinois average of 41.8 inches. However, 43 extreme heat days and a high 4627 growing degree days mean evaporation happens quickly, stressing cool-season grasses.
Acidic Soil and Clay Mix
A soil pH of 6.25 is on the lower end of the ideal range, meaning a light lime application may benefit some lawns. The soil's 23.2% clay content can lead to drainage issues during those heavy 51-inch rainfall years.
Resilient Moisture Levels This Year
Union County only experienced 17 weeks in drought over the last year, which is low compared to northern neighbors. While 100% of the area is currently 'abnormally dry,' the high annual rainfall helps the landscape recover quickly.
Start Early in Zone 7a
With the last frost occurring early on April 8, the growing season starts fast. Heat-tolerant Tall Fescue or even warm-season Zoysia are recommended to withstand the 43 days of temperatures over 90°F.
Lawn Difficulty Score
Recommended Grasses
Tall Fescue
Festuca arundinacea
Bermudagrass
Cynodon dactylon
Climate Snapshot
Annual Precip
51.1"
Growing Degree Days
4,626.7
Base 50F
Last Spring Frost
04/08
First Fall Frost
10/29
Days Above 95F
43
Hardiness Zone
7a
Seeding Calendar — Zone 7A
Seasonal Lawn Care Checklist
Spring
- Apply pre-emergent herbicide when soil reaches 55F
- Begin mowing when grass reaches 3 inches
- 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
- Overseed warm-season lawns if thinning
- Apply fall fertilizer (highest N application for cool-season)
- Continue mowing until growth stops
- Rake or mulch leaves to prevent smothering
Winter
- Apply pre-emergent for winter weeds
- Service mower and sharpen blades
- Plan spring soil amendments based on fall test
- Keep lawn clear of debris
Watering Deficit Calculator
Monthly Deficit
0.0"
inches of water
Monthly Water
0
gallons
Estimated Monthly Cost
$0.00
at $0.008/gallon average
Estimates based on 51" annual precipitation and estimated evapotranspiration. Actual costs vary by local water rates.
Common Lawn Problems in Union County
Excess Moisture & Fungal Disease
High annual rainfall (51 inches) increases risk of fungal diseases like brown patch and dollar spot. Ensure good drainage and avoid overwatering.
Learn more about regional lawn challenges at The Lawn Report.
Want detailed soil composition, drainage classes, and soil series data? View soil details on SoilByCounty.com
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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