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When to Plant Cabbage in Roosevelt County, MT

Roosevelt County, Montana Zone 4a May

Roosevelt County, Montana gardeners: here's your May plan

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

Avg. last frost May 17
Avg. first frost September 18
Soil temp (4") 28°F
Watering High
Pest pressure Low
Daylight 15 hrs
  1. Plant out cabbage

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Plant cabbage from seed, right in the garden

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

Get ahead of June
  • Starting indoors: cabbage
  • Fall sowing: cabbage

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Cabbage is a versatile cool-season crop that forms dense, leafy heads in green, red, or savoy varieties. It is a staple for coleslaw, sauerkraut, and many global cuisines.

Roosevelt County, Montana is in USDA Zone 4a. The average last spring frost is May 17 and the first fall frost is September 18, giving you a growing season of approximately 124 days.

At an elevation of 7,123 feet, Roosevelt County receives approximately 19.8 inches of rainfall annually with predominantly loam soil. Summer highs average 78°F, so choose short-season varieties of Cabbage to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Cabbage successfully. Mulch heavily to conserve soil moisture.

Roosevelt County, MT (Zone 4a) Short season
124 days
Last Spring Frost May 17
124 growing days
First Fall Frost September 18

Roosevelt County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (4 days to spare)
Start indoors: Apr 1 Transplant: May 13 🍅 Harvest: Jul 15 – Sep 9
Recommended (50%) ✓ Fits season (5 days to spare)
Start indoors: Apr 5 Transplant: May 17 🍅 Harvest: Jul 19 – Sep 13
Safe Start (90%) ✓ Fits season (0 days to spare)
Start indoors: Apr 22 Transplant: Jun 3 🍅 Harvest: Aug 5 – Sep 30

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 Roosevelt County

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

Soil pH

Your soil pH (6.7–7.7) overlaps with Cabbage's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help Cabbage.

How to Plant Cabbage

1"
Planting Depth
15"
Between Plants
24"
Between Rows

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

Succession Planting Cabbage

2
successive plantings in your 124-day season

Sow every 6.9 weeks. Last sowing by Jun 10 to harvest before frost.

For a dedicated fall crop, sow by Jun 26.

Plant Water Budget

Plant needs
0.9″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 304 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Cabbage

Cabbage needs approximately 0.9 inches of water per week (3.9" per month). Here's how your county's rainfall compares month by month.

Month Cabbage Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 3.9" 2.3" 1.6" 💧 Light watering
Jun 3.9" 1.5" 2.4" 🚿 Regular watering
Jul 3.9" 1.6" 2.3" 🚿 Regular watering
Aug 3.9" 1.9" 2" 🚿 Regular watering
Sep 3.9" 1.7" 2.2" 🚿 Regular watering
Oct 1.8" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Roosevelt County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Cabbage 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.

Cabbage needs ~680 GDD — county provides 1,054 GDD Excellent fit

Cabbage Planting Timeline — Roosevelt County, MT

Cabbage Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 17 May 17 – May 31
Direct Sow May 10 May 10 – May 31
Harvest July 19 Jul 19 – Sep 13
Fall Sowing June 26 Jun 26 – Jul 10

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.9"/week · Only during dry spells

📅 Days to Maturity

60–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

124 days in Roosevelt County

Growing Tips for Cabbage in Roosevelt County

Direct sow Cabbage outdoors after May 17 in Roosevelt County when soil has warmed and frost danger has passed.

Common pests for Cabbage in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

Roosevelt County receives only 20" of rain annually. Cabbage needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start seeds indoors 4-6 weeks before last frost. Space plants 18-24 inches apart. Keep soil evenly moist to prevent heads from splitting.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries
  • Tomatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cabbage in Roosevelt County, MT?

Roosevelt County is in Zone 4a with an average last frost of May 17. Plan your Cabbage planting based on this frost date — see the calendar above for exact timing.

What planting zone is Roosevelt County, MT?

Roosevelt County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 17 and first fall frost is September 18.

🌱

Your Roosevelt County Garden Planner — Free

A 24-page printable planner built for Roosevelt 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Roosevelt 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.