When to Plant Blueberries in Warren County, IL
Blueberries are long-lived shrubs producing sweet, antioxidant-rich berries. They require acidic soil and are attractive ornamental plants with fall color and spring flowers.
Warren County, Illinois is in USDA Zone 5a. The average last spring frost is April 13 and the first fall frost is October 21, giving you a growing season of approximately 191 days.
At an elevation of 801 feet, Warren County receives approximately 36.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Blueberries during the growing season.
Warren County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-6.8
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Blueberries Planting Timeline — Warren County, IL
Blueberries Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 4 | May 4 – May 18 |
· 48" apart · Rows 72" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | — |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
730–1095 days
Soil pH
4.5 – 5.5
USDA Zone
Zone 5a
Growing Season
191 days
Growing Tips for Warren County
Plant at least two varieties for cross-pollination. Acidify soil with sulfur or pine needle mulch to maintain pH 4.5-5.5. Protect ripening berries from birds with netting.
Companion Planting
Good Companions
Level Up Your Garden
Blueberries in Other Locations
Frequently Asked Questions
When should I plant Blueberries in Warren County, IL?
Warren County is in Zone 5a with an average last frost of April 13. Plan your Blueberries planting based on this frost date — see the calendar above for exact timing.
What planting zone is Warren County, IL?
Warren County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 13 and first fall frost is October 21.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Warren County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.
Get Your Free Garden Planner →Free download. Plan your entire garden season in minutes.