When to Plant Corn in Dallas County, IA
May in Dallas County, Iowa — your action list
If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.
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Put corn seeds straight in the ground
Your soil is 57°F — warm enough for these to germinate without babying.
Corn is a warm-season grass grown for its sweet ears, which are best eaten soon after harvest. It is wind-pollinated and must be planted in blocks for good kernel fill.
Dallas County, Iowa is in USDA Zone 5b. The average last spring frost is April 24 and the first fall frost is October 9, giving you a growing season of approximately 168 days.
At an elevation of 693 feet, Dallas County receives approximately 37.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Corn during the growing season.
Dallas County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-7
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 Dallas County
How your county's soil matches Corn's growing requirements.
Soil pH
Your soil pH (5.9–7.0) overlaps with Corn's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Dallas County is excellent for Corn — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.9%) — Corn will thrive.
How to Plant Corn
Succession Planting Corn
Sow every 6.9 weeks. Last sowing by Jul 01 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Corn
Corn needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.
| Month | Corn Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.8" | 0" | ❄️ Dormant |
| Mar | — | 2.5" | 0" | ❄️ Dormant |
| Apr | 6.5" | 3.6" | 2.9" | 💧 Light watering |
| May | 6.5" | 3.9" | 2.6" | 💧 Light watering |
| Jun | 6.5" | 4.8" | 1.7" | 💧 Light watering |
| Jul | 6.5" | 4.3" | 2.2" | 💧 Light watering |
| Aug | 6.5" | 4.5" | 2" | 💧 Light watering |
| Sep | 6.5" | 3.6" | 2.9" | 💧 Light watering |
| Oct | 6.5" | 2.7" | 3.8" | 🚿 Regular watering |
| Nov | — | 2.4" | 0" | ❄️ Dormant |
| Dec | — | 2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Dallas County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Corn Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Corn Planting Timeline — Dallas County, IA
Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | May 1 | May 1 – May 22 |
| Harvest | July 3 | Jul 3 – Aug 28 |
Plant 1" deep · 12" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.5"/week · 1-2 times/week
📅 Days to Maturity
60–100 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 5b
📆 Growing Season
168 days in Dallas County
Growing Tips for Corn in Dallas County
Direct sow Corn outdoors after April 24 in Dallas County when soil has warmed and frost danger has passed.
Common pests for Corn in this region include corn earworm and corn borers. Use row covers early in the season and inspect plants weekly.
General growing tips
Plant in blocks of at least 4 rows rather than single rows for proper pollination. Direct sow after soil reaches 60F. Side-dress with nitrogen when plants are knee-high.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Corn in Other Locations
Frequently Asked Questions
When should I plant Corn in Dallas County, IA?
Dallas County is in Zone 5b with an average last frost of April 24. Plan your Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Dallas County, IA?
Dallas County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 24 and first fall frost is October 9.
Your Dallas County Garden Planner — Free
A 24-page printable planner built for Dallas County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.