When to Plant Squash (Summer) in Marshall County, IA
May in Marshall 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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Harden off and plant squash (summer)
Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.
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Plant squash (summer) from seed, right in the garden
These tolerate cool soil, so you're not gambling by sowing now.
To set up a strong June, finish these tasks
- Starting indoors: squash (summer)
Summer squash includes zucchini, yellow crookneck, and pattypan varieties that are harvested young and tender. They are prolific producers in warm weather.
Marshall County, Iowa is in USDA Zone 5a. The average last spring frost is May 2 and the first fall frost is October 7, giving you a growing season of approximately 158 days.
At an elevation of 1,379 feet, Marshall County receives approximately 33.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Squash (Summer) to ensure they mature before fall.
Marshall County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-7.1
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 Marshall County
How your county's soil matches Squash (Summer)'s growing requirements.
Soil pH
Your soil pH (6.2–7.1) is within Squash (Summer)'s preferred range (6.0–7.5).
Soil Texture
The silt loam soil in Marshall County is excellent for Squash (Summer) — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.5%) — Squash (Summer) will thrive.
How to Plant Squash (Summer)
Succession Planting Squash (Summer)
Sow every 5.1 weeks. Last sowing by Aug 03 to harvest before frost.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Squash (Summer)
Squash (Summer) needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Squash (Summer) Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2.2" | 0" | ❄️ Dormant |
| Apr | — | 3" | 0" | ❄️ Dormant |
| May | 4.3" | 3.5" | 0.8" | 💧 Light watering |
| Jun | 4.3" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4" | 0.3" | 💧 Light watering |
| Aug | 4.3" | 3.5" | 0.8" | 💧 Light watering |
| Sep | 4.3" | 2.9" | 1.4" | 💧 Light watering |
| Oct | 4.3" | 2.3" | 2" | 💧 Light watering |
| Nov | — | 2.3" | 0" | ❄️ Dormant |
| Dec | — | 1.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Marshall County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Squash (Summer) 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.
Squash (Summer) Planting Timeline — Marshall County, IA
Squash (Summer) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 28 | Mar 28 – Apr 11 |
| Transplant Outdoors | May 16 | May 16 – May 30 |
| Direct Sow | May 9 | May 9 – May 30 |
| Harvest | July 4 | Jul 4 – Sep 5 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
45–65 days
🧪 Soil pH
Needs 6–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 5a
📆 Growing Season
158 days in Marshall County
Growing Tips for Squash (Summer) in Marshall County
Direct sow Squash (Summer) outdoors after May 02 in Marshall County when soil has warmed and frost danger has passed.
Common pests for Squash (Summer) in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow after last frost on mounds. Harvest frequently when fruits are 6-8 inches for best texture. Check plants daily as they grow rapidly in summer heat.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Squash (Summer) in Other Locations
Frequently Asked Questions
When should I plant Squash (Summer) in Marshall County, IA?
Marshall County is in Zone 5a with an average last frost of May 2. Plan your Squash (Summer) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Marshall County, IA?
Marshall County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is May 2 and first fall frost is October 7.
Your Marshall County Garden Planner — Free
A 24-page printable planner built for Marshall County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.