When to Plant Garlic in Johnson County, IA
Garlic is a pungent allium planted in fall and harvested the following summer. Hardneck varieties produce edible flower stalks (scapes) and are more cold-hardy.
Johnson County, Iowa is in USDA Zone 5a. The average last spring frost is April 24 and the first fall frost is October 11, giving you a growing season of approximately 170 days.
At an elevation of 1,204 feet, Johnson County receives approximately 40.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Garlic during the growing season.
Johnson County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-7.3
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
Garlic Planting Timeline — Johnson County, IA
Garlic Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Fall Sowing | August 30 | Aug 30 – Sep 13 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | — |
| June | — |
| July | — |
| August | Fall Sowing |
| September | Fall Sowing |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
90–240 days
Soil pH
6 – 7.5
USDA Zone
Zone 5a
Growing Season
170 days
Growing Tips for Johnson County
Plant individual cloves pointed end up in fall, 6 weeks before ground freezes. Mulch heavily with straw. Harvest when lower leaves begin to brown but 5-6 green leaves remain.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Garlic in Other Locations
Frequently Asked Questions
When should I plant Garlic in Johnson County, IA?
Johnson County is in Zone 5a with an average last frost of April 24. Plan your Garlic planting based on this frost date — see the calendar above for exact timing.
What planting zone is Johnson County, IA?
Johnson County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 24 and first fall frost is October 11.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Johnson County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.
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