When to Plant Spinach in Sweet Grass County, MT
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.
Sweet Grass County, Montana is in USDA Zone 4b. The average last spring frost is May 22 and the first fall frost is September 19, giving you a growing season of approximately 120 days.
At an elevation of 7,534 feet, Sweet Grass County receives approximately 16.9 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Spinach to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Spinach successfully. Mulch heavily to conserve soil moisture.
Sweet Grass County Soil Profile
Soil Type
Loam
Soil pH
6.7-8.4
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.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Spinach Planting Timeline — Sweet Grass County, MT
Spinach Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 10 | Apr 10 – Apr 24 |
| Transplant Outdoors | May 22 | May 22 – Jun 5 |
| Direct Sow | May 15 | May 15 – Jun 5 |
| Fall Sowing | June 27 | Jun 27 – Jul 11 |
| Harvest | June 26 | Jun 26 – Aug 28 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow Fall Sowing Harvest |
| July | Fall Sowing Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Partial Shade (3-6 hours)
Water
Moderate — regular watering
Days to Maturity
35–50 days
Soil pH
6.5 – 7.5
USDA Zone
Zone 4b
Growing Season
120 days
Growing Tips for Sweet Grass County
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
Wind pollinated — isolate 1/2 mile for purity. Easy to let bolt in heat.
Spinach in Other Locations
Frequently Asked Questions
When should I plant Spinach in Sweet Grass County, MT?
Sweet Grass County is in Zone 4b with an average last frost of May 22. Plan your Spinach planting based on this frost date — see the calendar above for exact timing.
What planting zone is Sweet Grass County, MT?
Sweet Grass County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 22 and first fall frost is September 19.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Sweet Grass County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.
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