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When to Plant Kohlrabi in Sheridan County, MT

Sheridan County, Montana Zone 3b May

What to do in May

A quick May briefing for Sheridan County, Montana gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 17
Avg. first frost September 18
Soil temp (4") 26°F
Watering High
Pest pressure Low
Daylight 15 hrs
  1. Move kohlrabi into the garden

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

  2. Direct-sow kohlrabi

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

A few tasks this May that'll pay off in June
  • Starting indoors: kohlrabi
  • Fall sowing: kohlrabi

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Kohlrabi is an unusual brassica that forms a swollen stem above ground with a mild, sweet turnip-like flavor. Both the bulb and tender leaves are edible.

Sheridan County, Montana is in USDA Zone 3b. 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 8,209 feet, Sheridan County receives approximately 16.8 inches of rainfall annually with predominantly loam soil. Summer highs average 79°F, so choose short-season varieties of Kohlrabi to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Kohlrabi successfully. Mulch heavily to conserve soil moisture.

Sheridan County, MT (Zone 3b) Short season
124 days
Last Spring Frost May 17
124 growing days
First Fall Frost September 18
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Sheridan County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (39 days to spare)
Start indoors: Apr 1 Transplant: May 13 🍅 Harvest: Jul 1 – Aug 5
Recommended (50%) ✓ Fits season (40 days to spare)
Start indoors: Apr 5 Transplant: May 17 🍅 Harvest: Jul 5 – Aug 9
Safe Start (90%) ✓ Fits season (35 days to spare)
Start indoors: Apr 22 Transplant: Jun 3 🍅 Harvest: Jul 22 – Aug 26

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 Sheridan County

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

Soil pH

Your soil pH (6.3–7.9) overlaps with Kohlrabi's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Kohlrabi.

How to Plant Kohlrabi

0.5"
Planting Depth
4"
Between Plants
12"
Between Rows

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

Succession Planting Kohlrabi

3
successive plantings in your 124-day season

Sow every 5.1 weeks. Last sowing by Jul 15 to harvest before frost.

For a dedicated fall crop, sow by Jun 26.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.6″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 173 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Kohlrabi

Kohlrabi needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Kohlrabi Needs Rainfall You Supplement Action
Jan 1.1" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.6" 0" ❄️ Dormant
Apr 1.7" 0" ❄️ Dormant
May 3" 2.1" 0.9" 💧 Light watering
Jun 3" 1.2" 1.8" 🚿 Regular watering
Jul 3" 1.5" 1.5" 🚿 Regular watering
Aug 3" 1.9" 1.1" 💧 Light watering
Sep 3" 1.2" 1.8" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 1.1" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

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

Kohlrabi 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.

Kohlrabi needs ~509 GDD — county provides 1,147 GDD Excellent fit

Kohlrabi Planting Timeline — Sheridan County, MT

Kohlrabi 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 5 Jul 5 – Aug 9
Fall Sowing June 26 Jun 26 – Jul 10

Plant 0.5" deep · 4" apart · Rows 12" 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
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.7"/week · Only during dry spells

📅 Days to Maturity

45–65 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 3b

📆 Growing Season

124 days in Sheridan County

Growing Tips for Kohlrabi in Sheridan County

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

Common pests for Kohlrabi 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 in spring or fall. Harvest when bulbs are 2-3 inches in diameter for best texture and flavor. Larger bulbs may become woody and fibrous.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Kohlrabi in Sheridan County, MT?

Sheridan County is in Zone 3b with an average last frost of May 17. Plan your Kohlrabi planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sheridan County, MT?

Sheridan County, Montana is in USDA Hardiness Zone 3b. The average last spring frost is May 17 and first fall frost is September 18.

🌱

Your Sheridan County Garden Planner — Free

A 24-page printable planner built for Sheridan County (Zone 3b). 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 Sheridan 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.