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When to Plant Kale in Missoula County, MT

Missoula County, Montana Zone 5b May

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

Your Missoula County, Montana garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost May 14
Avg. first frost September 23
Soil temp (4") 32°F
Watering High
Pest pressure Low
Daylight 14.9 hrs
  1. Set out kale seedlings

    Frost risk is low now in Missoula County, Montana. If you've been covering beds overnight, you can stop.

June will be here before you know it — start on
  • Starting indoors: kale

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Kale is an exceptionally hardy, nutrient-dense green available in curly, lacinato, and Russian varieties. It tolerates heavy frost and often tastes sweeter after cold exposure.

Missoula County, Montana is in USDA Zone 5b. The average last spring frost is May 14 and the first fall frost is September 23, giving you a growing season of approximately 132 days.

At an elevation of 8,019 feet, Missoula County receives approximately 15.9 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Kale during the growing season. With low rainfall, drip irrigation is essential for growing Kale successfully. Mulch heavily to conserve soil moisture.

Missoula County, MT (Zone 5b) Short season
132 days
Last Spring Frost May 14
132 growing days
First Fall Frost September 23
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Missoula County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (22 days to spare)
Start indoors: Apr 3 Transplant: May 8 🍅 Harvest: Jul 3 – Aug 28
Recommended (50%) ✓ Fits season (20 days to spare)
Start indoors: Apr 9 Transplant: May 14 🍅 Harvest: Jul 9 – Sep 3
Safe Start (90%) ✓ Fits season (19 days to spare)
Start indoors: Apr 30 Transplant: Jun 4 🍅 Harvest: Jul 30 – Sep 24

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 Missoula County

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

Soil pH

Your soil pH (6.2–7.7) overlaps with Kale's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Kale.

How to Plant Kale

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Kale

3
successive plantings in your 132-day season

Sow every 5.7 weeks. Last sowing by Jul 15 to harvest before frost.

For a dedicated fall crop, sow by Jul 15.

Plant Water Budget

Plant needs
0.8″/week
Rainfall provides
0.5″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 415 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Kale

Kale needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.

Month Kale Needs Rainfall You Supplement Action
Jan 1" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.6" 0" ❄️ Dormant
Apr 1.7" 0" ❄️ Dormant
May 3.5" 1.7" 1.8" 🚿 Regular watering
Jun 3.5" 1.1" 2.4" 🚿 Regular watering
Jul 3.5" 1.3" 2.2" 🚿 Regular watering
Aug 3.5" 1.9" 1.6" 💧 Light watering
Sep 3.5" 1.4" 2.1" 🚿 Regular watering
Oct 1.5" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 1" 0" ❄️ Dormant

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

Kale 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.

Kale needs ~915 GDD — county provides 2,013 GDD Excellent fit

Kale Planting Timeline — Missoula County, MT

Kale Planting Calendar

Activity When Date Range
Start Indoors April 9 Apr 9 – Apr 23
Transplant Outdoors May 14 May 14 – May 28
Direct Sow April 30 Apr 30 – May 21
Harvest July 9 Jul 9 – Sep 3
Fall Sowing July 15 Jul 15 – Jul 29

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · 1-2 times/week

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

132 days in Missoula County

Growing Tips for Kale in Missoula County

Direct sow Kale outdoors after May 14 in Missoula County when soil has warmed and frost danger has passed.

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

General growing tips

Direct sow or transplant in early spring or late summer. Harvest outer leaves first to keep plants productive. Kale overwinters in many climates and can provide greens all year.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries
  • Tomatoes

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Kale Seeds
Life Cycle Biennial
Pollination Cross-Pollinated (insects)
How to Collect Allow 2nd year flower stalks to dry. Harvest pods when tan.
Storage Store airtight; viable 5 years at 35°F, under 50% humidity.

Isolate 1/2 mile from other brassicas (broccoli, cabbage, etc.) — they all cross.

Frequently Asked Questions

When should I plant Kale in Missoula County, MT?

Missoula County is in Zone 5b with an average last frost of May 14. Plan your Kale planting based on this frost date — see the calendar above for exact timing.

What planting zone is Missoula County, MT?

Missoula County, Montana is in USDA Hardiness Zone 5b. The average last spring frost is May 14 and first fall frost is September 23.

🌱

Your Missoula County Garden Planner — Free

A 24-page printable planner built for Missoula County (Zone 5b). 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 Missoula 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.