When to Plant Dill in O'Brien County, IA
Dill is a feathery annual herb with aromatic leaves and seeds. Its fine foliage and umbrella-shaped flower heads attract beneficial insects to the garden.
O'Brien County, Iowa is in USDA Zone 4b. The average last spring frost is May 1 and the first fall frost is October 5, giving you a growing season of approximately 157 days.
At an elevation of 658 feet, O'Brien County receives approximately 40.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Dill to ensure they mature before fall.
O'Brien County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-7.2
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.
Soil Compatibility in O'Brien County
How your county's soil matches Dill's growing requirements.
Soil pH
Your soil pH (5.8–7.2) overlaps with Dill's range (5.5–7.0), though not a perfect match.
Soil Texture
The silt loam soil in O'Brien County is excellent for Dill — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.1%) — Dill will thrive.
How to Plant Dill
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Succession Planting Dill
Sow every 4.6 weeks. Last sowing by Aug 06 to harvest before frost.
For a dedicated fall crop, sow by Jul 13.
Plant Water Budget
Dill Planting Timeline — O'Brien County, IA
Dill Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 20 | Mar 20 – Apr 3 |
| Transplant Outdoors | April 24 | Apr 24 – May 8 |
| Direct Sow | April 24 | Apr 24 – May 15 |
| Fall Sowing | July 13 | Jul 13 – Jul 27 |
| Harvest | June 5 | Jun 5 – Aug 7 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Fall Sowing Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
40–60 days
🧪 Soil pH
Needs 5.5–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 4b
📆 Growing Season
157 days in O'Brien County
Growing Tips for Dill in O'Brien County
Direct sow Dill outdoors after May 01 in O'Brien County when soil has warmed and frost danger has passed.
Your generous 157.0-day season in O'Brien County allows multiple plantings of Dill. Sow every 20.0 days for continuous harvest.
Common pests for Dill in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow in spring as dill has a taproot and dislikes transplanting. Succession sow for continuous leaf harvest. Allow some plants to flower for seeds and to attract beneficial insects.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Dill in Other Locations
Frequently Asked Questions
When should I plant Dill in O'Brien County, IA?
O'Brien County is in Zone 4b with an average last frost of May 1. Plan your Dill planting based on this frost date — see the calendar above for exact timing.
What planting zone is O'Brien County, IA?
O'Brien County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is May 1 and first fall frost is October 5.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help O'Brien County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.
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