When to Plant Watermelon in Davis County, IA
What to do in May
A quick May briefing for Davis County, Iowa gardeners — what's urgent, what's next, and what can wait.
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Transplant watermelon outside
Frost risk is low now in Davis County, Iowa. If you've been covering beds overnight, you can stop.
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Fire up the seed-starting tray: watermelon
You're about 23 weeks out from your last frost — the perfect window to get these germinating indoors.
Watermelon is a sprawling vine crop that produces sweet, juicy fruits in hot weather. Varieties range from personal-sized icebox types to 50-pound giants.
Davis County, Iowa is in USDA Zone 5b. The average last spring frost is April 19 and the first fall frost is October 16, giving you a growing season of approximately 180 days.
At an elevation of 859 feet, Davis County receives approximately 30.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Watermelon during the growing season.
Davis County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-6.7
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 Davis County
How your county's soil matches Watermelon's growing requirements.
Soil pH
Your soil pH (6.2–6.7) is within Watermelon's preferred range (6.0–7.5).
Soil Texture
The silt loam soil in Davis County is excellent for Watermelon — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.7%) — Watermelon will thrive.
How to Plant Watermelon
Succession Planting Watermelon
Sow every 8 weeks. Last sowing by Jul 08 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Watermelon
Watermelon 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 | Watermelon Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.4" | 0" | ❄️ Dormant |
| Mar | — | 2.3" | 0" | ❄️ Dormant |
| Apr | 6.5" | 2.9" | 3.6" | 🚿 Regular watering |
| May | 6.5" | 3.7" | 2.8" | 💧 Light watering |
| Jun | 6.5" | 4" | 2.5" | 💧 Light watering |
| Jul | 6.5" | 3.6" | 2.9" | 💧 Light watering |
| Aug | 6.5" | 2.6" | 3.9" | 🚿 Regular watering |
| Sep | 6.5" | 2.3" | 4.2" | 🚿 Regular watering |
| Oct | 6.5" | 2.5" | 4" | 🚿 Regular watering |
| Nov | — | 2.2" | 0" | ❄️ Dormant |
| Dec | — | 1.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Davis County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Watermelon 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.
Watermelon Planting Timeline — Davis County, IA
Watermelon Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 15 | Mar 15 – Mar 29 |
| Transplant Outdoors | May 3 | May 3 – May 17 |
| Direct Sow | April 26 | Apr 26 – May 17 |
| Harvest | July 12 | Jul 12 – Aug 30 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.5"/week · 2-3 times/week
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
180 days in Davis County
Growing Tips for Watermelon in Davis County
Direct sow Watermelon outdoors after April 19 in Davis County when soil has warmed and frost danger has passed.
Common pests for Watermelon in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors 3-4 weeks early or direct sow after soil is warm. Plant on mounds with plenty of space. Check ripeness by looking for a yellow ground spot and dull thump when tapped.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Watermelon in Other Locations
Frequently Asked Questions
When should I plant Watermelon in Davis County, IA?
Davis County is in Zone 5b with an average last frost of April 19. Plan your Watermelon planting based on this frost date — see the calendar above for exact timing.
What planting zone is Davis County, IA?
Davis County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 19 and first fall frost is October 16.
Your Davis County Garden Planner — Free
A 24-page printable planner built for Davis 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.