When to Plant Squash (Winter) in Sully County, SD
May in Sully County, South Dakota — your action list
Here's what deserves your attention in Sully County, South Dakota this month. Everything below is tailored to Zone 4b and timed around your local frost dates.
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Outdoor sowing time: squash (winter)
These tolerate cool soil, so you're not gambling by sowing now.
A few tasks this May that'll pay off in June
- Transplants going out: squash (winter)
- Starting indoors: squash (winter)
Winter squash includes butternut, acorn, delicata, and hubbard varieties grown to full maturity with hard rinds for storage. They develop sweet, dense flesh.
Sully County, South Dakota is in USDA Zone 4b. The average last spring frost is May 11 and the first fall frost is October 3, giving you a growing season of approximately 145 days.
At an elevation of 650 feet, Sully County receives approximately 26.8 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Squash (Winter) to ensure they mature before fall.
Sully County Soil Profile
Soil Type
Loam
Soil pH
6.7-7.8
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 Sully County
How your county's soil matches Squash (Winter)'s growing requirements.
Soil pH
Your soil pH (6.7–7.8) is more alkaline than Squash (Winter) prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Sully County is excellent for Squash (Winter) — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.6%). Annual compost additions will help Squash (Winter).
How to Plant Squash (Winter)
Succession Planting Squash (Winter)
Sow every 9.1 weeks. Last sowing by Jun 05 to harvest before frost.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Squash (Winter)
Squash (Winter) 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 (Winter) Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | — | 2.8" | 0" | ❄️ Dormant |
| May | 4.3" | 3" | 1.3" | 💧 Light watering |
| Jun | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Jul | 4.3" | 2.5" | 1.8" | 💧 Light watering |
| Aug | 4.3" | 2.8" | 1.5" | 💧 Light watering |
| Sep | 4.3" | 2.3" | 2" | 💧 Light watering |
| Oct | 4.3" | 2.6" | 1.7" | 💧 Light watering |
| Nov | — | 1.7" | 0" | ❄️ Dormant |
| Dec | — | 1.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Sully County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Squash (Winter) 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 (Winter) Planting Timeline — Sully County, SD
Squash (Winter) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 30 | Mar 30 – Apr 13 |
| Transplant Outdoors | June 1 | Jun 1 – Jun 15 |
| Direct Sow | May 25 | May 25 – Jun 15 |
| Harvest | August 24 | Aug 24 – Oct 19 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
80–120 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 4b
📆 Growing Season
145 days in Sully County
Growing Tips for Squash (Winter) in Sully County
Direct sow Squash (Winter) outdoors after May 11 in Sully County when soil has warmed and frost danger has passed.
Common pests for Squash (Winter) 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 rich mounds. Allow ample space for sprawling vines. Cure harvested fruits in the sun for 10 days before storing in a cool, dry place.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Squash (Winter) in Other Locations
Frequently Asked Questions
When should I plant Squash (Winter) in Sully County, SD?
Sully County is in Zone 4b with an average last frost of May 11. Plan your Squash (Winter) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Sully County, SD?
Sully County, South Dakota is in USDA Hardiness Zone 4b. The average last spring frost is May 11 and first fall frost is October 3.
Your Sully County Garden Planner — Free
A 24-page printable planner built for Sully County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.