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When to Plant Spinach in Sublette County, WY

Spinach is a nutrient-packed cool-season green that grows quickly in spring and fall. It is rich in iron, vitamins, and antioxidants and excellent raw or cooked.

Sublette County, Wyoming is in USDA Zone 3b. The average last spring frost is June 22 and the first fall frost is August 24, giving you a growing season of approximately 63 days.

At an elevation of 5,005 feet, Sublette County receives approximately 22.8 inches of rainfall annually with predominantly loam soil. Summer highs average 81ยฐF, so choose short-season varieties of Spinach to ensure they mature before fall.

Sublette County, WY (Zone 3b) Very short season
63 days
Last Spring Frost June 22
63 growing days
First Fall Frost August 24

Sublette County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: May 6 Transplant: Jun 17 🍅 Harvest: Jul 22 – Sep 23
Recommended (50%) ✗ May not fit
Start indoors: May 11 Transplant: Jun 22 🍅 Harvest: Jul 27 – Sep 28
Safe Start (90%) ✗ May not fit
Start indoors: May 19 Transplant: Jun 30 🍅 Harvest: Aug 4 – Oct 6

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 Sublette County

How your county's soil matches Spinach's growing requirements.

Soil pH

Your soil pH (6.7โ€“7.8) overlaps with Spinach's range (6.5โ€“7.5), though not a perfect match.

Soil Texture

The loam soil in Sublette County is excellent for Spinach โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Spinach.

How to Plant Spinach

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Spinach

2
successive plantings in your 63-day season

Sow every 4 weeks. Last sowing by Jul 05 to harvest before frost.

For a dedicated fall crop, sow by Jun 01.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
1.5″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Spinach needs ~457 GDD — county provides 677 GDD Excellent fit

Spinach Planting Timeline โ€” Sublette County, WY

Spinach Planting Calendar

Activity When Date Range
Start Indoors May 11 May 11 โ€“ May 25
Transplant Outdoors June 22 Jun 22 โ€“ Jul 6
Direct Sow June 15 Jun 15 โ€“ Jul 6
Fall Sowing June 1 Jun 1 โ€“ Jun 15
Harvest July 27 Jul 27 โ€“ Sep 28

Plant 0.5" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May Start Indoors
June Transplant Outdoors Direct Sow Fall Sowing
July Transplant Outdoors Direct Sow Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

โ˜€๏ธ Sun

Partial Shade (3-6 hours)

๐Ÿ’ง Water

0.7"/week ยท Natural rainfall sufficient

๐Ÿ“… Days to Maturity

35โ€“50 days

๐Ÿงช Soil pH

Needs 6.5โ€“7.5 ยท Your soil: acceptable

๐Ÿ—บ๏ธ USDA Zone

Zone 3b

๐Ÿ“† Growing Season

63 days in Sublette County

Growing Tips for Spinach in Sublette County

Direct sow Spinach outdoors after June 22 in Sublette County when soil has warmed and frost danger has passed.

General growing tips

Direct sow as soon as soil can be worked in spring. Plant in partial shade for summer crops to delay bolting. Succession plant every 2 weeks for continuous harvest.

Companion Planting

Good Companions

Level Up Your Garden

๐ŸŒพ Save Your Own Spinach Seeds
Life Cycle Annual
Pollination Wind Pollinated
How to Collect Let plants bolt. Harvest seed stalks when seeds turn tan.
Storage Store airtight; viable 5 years at 35ยฐF, under 45% humidity.

Wind pollinated โ€” isolate 1/2 mile for purity. Easy to let bolt in heat.

Frequently Asked Questions

When should I plant Spinach in Sublette County, WY?

Sublette County is in Zone 3b with an average last frost of June 22. Plan your Spinach planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Sublette County, WY?

Sublette County, Wyoming is in USDA Hardiness Zone 3b. The average last spring frost is June 22 and first fall frost is August 24.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Sublette County gardeners in Zone 3b organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Sublette County, WY. Local conditions may vary. Last updated: April 2026.