When to Plant Spinach in Blaine County, MT
This month in Blaine County, Montana
May is a pivotal month for Blaine County, Montana gardens. Focus on these tasks first and you'll set up the rest of the season for success.
-
Harden off and plant spinach
Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.
-
Direct-sow spinach
These tolerate cool soil, so you're not gambling by sowing now.
June prep starts now
- Starting indoors: spinach
- First harvests: spinach
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.
Blaine County, Montana is in USDA Zone 4a. The average last spring frost is May 14 and the first fall frost is September 24, giving you a growing season of approximately 133 days.
At an elevation of 7,816 feet, Blaine County receives approximately 23.9 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.
Blaine County Soil Profile
Soil Type
Loam
Soil pH
6.4-7.7
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 Blaine County
How your county's soil matches Spinach's growing requirements.
Soil pH
Your soil pH (6.4–7.7) overlaps with Spinach's range (6.5–7.5), though not a perfect match.
Soil Texture
The loam soil in Blaine County is excellent for Spinach — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Spinach.
Organic Matter
Organic matter is moderate (2.7%). Annual compost additions will help Spinach.
How to Plant Spinach
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Succession Planting Spinach
Sow every 4 weeks. Last sowing by Aug 05 to harvest before frost.
For a dedicated fall crop, sow by Jul 02.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Spinach
Spinach needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.
| Month | Spinach Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 1.9" | 0" | ❄️ Dormant |
| Apr | — | 2.4" | 0" | ❄️ Dormant |
| May | 3" | 3.2" | 0" | ✅ Rainfall sufficient |
| Jun | 3" | 1.6" | 1.4" | 💧 Light watering |
| Jul | 3" | 2.3" | 0.7" | 💧 Light watering |
| Aug | 3" | 2.6" | 0.4" | 💧 Light watering |
| Sep | 3" | 1.8" | 1.2" | 💧 Light watering |
| Oct | — | 2" | 0" | ❄️ Dormant |
| Nov | — | 1.6" | 0" | ❄️ Dormant |
| Dec | — | 1.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Blaine County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Spinach 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.
Spinach Planting Timeline — Blaine County, MT
Spinach Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 2 | Apr 2 – Apr 16 |
| Transplant Outdoors | May 14 | May 14 – May 28 |
| Direct Sow | May 7 | May 7 – May 28 |
| Harvest | June 18 | Jun 18 – Aug 20 |
| Fall Sowing | July 2 | Jul 2 – Jul 16 |
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 | Harvest |
| July | Fall Sowing Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
0.7"/week · Only during dry spells
📅 Days to Maturity
35–50 days
🧪 Soil pH
Needs 6.5–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 4a
📆 Growing Season
133 days in Blaine County
Growing Tips for Spinach in Blaine County
Direct sow Spinach outdoors after May 14 in Blaine County when soil has warmed and frost danger has passed.
Your generous 133.0-day season in Blaine County allows multiple plantings of Spinach. Sow every 17.0 days for continuous harvest.
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
Check more plant combinations with our Companion Planting Checker →
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 Blaine County, MT?
Blaine County is in Zone 4a with an average last frost of May 14. Plan your Spinach planting based on this frost date — see the calendar above for exact timing.
What planting zone is Blaine County, MT?
Blaine County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 14 and first fall frost is September 24.
Your Blaine County Garden Planner — Free
A 24-page printable planner built for Blaine County (Zone 4a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.