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When to Plant Spinach in Pondera County, MT

Pondera County, Montana Zone 4a May

Your May planting checklist for Pondera County, Montana

We've pulled the most time-sensitive tasks for Pondera County, Montana this May and put them front and centre. Tackle them in order.

Avg. last frost May 23
Avg. first frost September 16
Soil temp (4") 28°F
Watering High
Pest pressure Low
Daylight 15 hrs
  1. Move spinach from tray to bed

    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.

  2. Sow spinach where they'll grow

    Your soil is 28°F — warm enough for these to germinate without babying.

Coming up in June — start thinking about
  • First harvests: spinach
  • Fall sowing: spinach

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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.

Pondera County, Montana is in USDA Zone 4a. The average last spring frost is May 23 and the first fall frost is September 16, giving you a growing season of approximately 116 days.

At an elevation of 8,118 feet, Pondera County receives approximately 18.4 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.

Pondera County, MT (Zone 4a) Short season
116 days
Last Spring Frost May 23
116 growing days
First Fall Frost September 16

Pondera County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (16 days to spare)
Start indoors: Apr 6 Transplant: May 18 🍅 Harvest: Jun 22 – Aug 24
Recommended (50%) ✓ Fits season (18 days to spare)
Start indoors: Apr 11 Transplant: May 23 🍅 Harvest: Jun 27 – Aug 29
Safe Start (90%) ✓ Fits season (12 days to spare)
Start indoors: Apr 28 Transplant: Jun 9 🍅 Harvest: Jul 14 – Sep 15

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 Pondera County

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

Soil pH

Your soil pH (6.6–8.3) overlaps with Spinach's range (6.5–7.5), though not a perfect match.

Soil Texture

The loam soil in Pondera County is excellent for Spinach — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.3%). 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

3
successive plantings in your 116-day season

Sow every 4 weeks. Last sowing by Jul 28 to harvest before frost.

For a dedicated fall crop, sow by Jun 24.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.7″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 42 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 1.3" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 3" 1.9" 1.1" 💧 Light watering
Jun 3" 1.4" 1.6" 🚿 Regular watering
Jul 3" 1.7" 1.3" 💧 Light watering
Aug 3" 2" 1" 💧 Light watering
Sep 3" 1.4" 1.6" 🚿 Regular watering
Oct 1.7" 0" ❄️ Dormant
Nov 1.3" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Pondera 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 needs ~489 GDD — county provides 1,334 GDD Excellent fit

Spinach Planting Timeline — Pondera County, MT

Spinach Planting Calendar

Activity When Date Range
Start Indoors April 11 Apr 11 – Apr 25
Transplant Outdoors May 23 May 23 – Jun 6
Direct Sow May 16 May 16 – Jun 6
Harvest June 27 Jun 27 – Aug 29
Fall Sowing June 24 Jun 24 – Jul 8

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

Month-by-Month Timeline

MonthActivities
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

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

116 days in Pondera County

Growing Tips for Spinach in Pondera County

Direct sow Spinach outdoors after May 23 in Pondera 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

Check more plant combinations with our Companion Planting Checker →

🌾 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 35°F, under 45% humidity.

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

Frequently Asked Questions

When should I plant Spinach in Pondera County, MT?

Pondera County is in Zone 4a with an average last frost of May 23. Plan your Spinach planting based on this frost date — see the calendar above for exact timing.

What planting zone is Pondera County, MT?

Pondera County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 23 and first fall frost is September 16.

🌱

Your Pondera County Garden Planner — Free

A 24-page printable planner built for Pondera 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.

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

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.