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When to Plant Kale in Lewis and Clark County, MT

Lewis and Clark County, Montana Zone 4b May

May to-do list for Lewis and Clark County, Montana

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

Avg. last frost May 29
Avg. first frost September 18
Soil temp (4") 33°F
Watering High
Pest pressure Low
Daylight 14.9 hrs
  1. Move kale into the garden

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Seed kale outdoors

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

Before June arrives, get these ready
  • Fall sowing: 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.

Lewis and Clark County, Montana is in USDA Zone 4b. The average last spring frost is May 29 and the first fall frost is September 18, giving you a growing season of approximately 112 days.

At an elevation of 7,064 feet, Lewis and Clark County receives approximately 22.2 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Kale to ensure they mature before fall.

Lewis and Clark County, MT (Zone 4b) Short season
112 days
Last Spring Frost May 29
112 growing days
First Fall Frost September 18
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Lewis and Clark County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (2 days to spare)
Start indoors: Apr 6 Transplant: May 18 🍅 Harvest: Jul 13 – Sep 7
Recommended (50%) ✓ Fits season (0 days to spare)
Start indoors: Apr 17 Transplant: May 29 🍅 Harvest: Jul 24 – Sep 18
Safe Start (90%) ✗ May not fit
Start indoors: May 8 Transplant: Jun 19 🍅 Harvest: Aug 14 – Oct 9

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 Lewis and Clark County

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

Soil pH

Your soil pH (6.5–8.1) overlaps with Kale's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Kale

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 Kale

2
successive plantings in your 112-day season

Sow every 5.7 weeks. Last sowing by Jul 10 to harvest before frost.

For a dedicated fall crop, sow by Jun 26.

Plant Water Budget

Plant needs
0.8″/week
Rainfall provides
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 1.6" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 2.3" 0" ❄️ Dormant
May 3.5" 2.6" 0.9" 💧 Light watering
Jun 3.5" 1.5" 2" 🚿 Regular watering
Jul 3.5" 1.9" 1.6" 💧 Light watering
Aug 3.5" 2.3" 1.2" 💧 Light watering
Sep 3.5" 1.8" 1.7" 💧 Light watering
Oct 1.7" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Lewis and Clark 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 ~690 GDD — county provides 1,288 GDD Excellent fit

Kale Planting Timeline — Lewis and Clark County, MT

Kale Planting Calendar

Activity When Date Range
Start Indoors April 17 Apr 17 – May 1
Transplant Outdoors May 29 May 29 – Jun 12
Direct Sow May 22 May 22 – Jun 12
Harvest July 24 Jul 24 – Sep 18
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 Start Indoors Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow Fall Sowing
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 · Natural rainfall sufficient

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

112 days in Lewis and Clark County

Growing Tips for Kale in Lewis and Clark County

Direct sow Kale outdoors after May 29 in Lewis and Clark 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.

Recommended Kale Varieties for Lewis and Clark County

Cold-hardy kale that improves in flavor after frost

Winterbor Red Russian Dwarf Blue Curled

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 Lewis and Clark County, MT?

Lewis and Clark County is in Zone 4b with an average last frost of May 29. Plan your Kale planting based on this frost date — see the calendar above for exact timing.

What planting zone is Lewis and Clark County, MT?

Lewis and Clark County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 29 and first fall frost is September 18.

🌱

Your Lewis and Clark County Garden Planner — Free

A 24-page printable planner built for Lewis and Clark County (Zone 4b). 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 Lewis and Clark 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.