When to Plant Kohlrabi in Blaine County, MT
This month in Blaine County, Montana
A quick May briefing for Blaine County, Montana gardeners — what's urgent, what's next, and what can wait.
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Harden off and plant kohlrabi
Frost risk is low now in Blaine County, Montana. If you've been covering beds overnight, you can stop.
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Plant kohlrabi 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: kohlrabi
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.
Blaine County, Montana is in USDA Zone 4a. The average last spring frost is May 14 and the first fall frost is September 24, giving you a growing season of approximately 133 days.
At an elevation of 7,816 feet, Blaine County receives approximately 23.9 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Kohlrabi to ensure they mature before fall.
Blaine County Soil Profile
Soil Type
Loam
Soil pH
6.4-7.7
Drainage
Well Drained
Plant Planting Risk Windows
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 Blaine County
How your county's soil matches Kohlrabi's growing requirements.
Soil pH
Your soil pH (6.4–7.7) overlaps with Kohlrabi's range (6.0–7.5), though not a perfect match.
Soil Texture
The loam soil in Blaine County is excellent for Kohlrabi — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Kohlrabi.
Organic Matter
Organic matter is moderate (2.7%). Annual compost additions will help Kohlrabi.
How to Plant Kohlrabi
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Succession Planting Kohlrabi
Sow every 5.1 weeks. Last sowing by Jul 21 to harvest before frost.
For a dedicated fall crop, sow by Jul 02.
Plant Water Budget
Water stress score is 6/10 — 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 | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 1.9" | 0" | ❄️ Dormant |
| Apr | — | 2.4" | 0" | ❄️ Dormant |
| May | 3" | 3.2" | 0" | ✅ Rainfall sufficient |
| Jun | 3" | 1.6" | 1.4" | 💧 Light watering |
| Jul | 3" | 2.3" | 0.7" | 💧 Light watering |
| Aug | 3" | 2.6" | 0.4" | 💧 Light watering |
| Sep | 3" | 1.8" | 1.2" | 💧 Light watering |
| Oct | — | 2" | 0" | ❄️ Dormant |
| Nov | — | 1.6" | 0" | ❄️ Dormant |
| Dec | — | 1.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Blaine 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 Planting Timeline — Blaine County, MT
Kohlrabi Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 2 | Apr 2 – Apr 16 |
| Transplant Outdoors | May 14 | May 14 – May 28 |
| Direct Sow | May 7 | May 7 – May 28 |
| Harvest | July 2 | Jul 2 – Aug 6 |
| Fall Sowing | July 2 | Jul 2 – Jul 16 |
Plant 0.5" deep · 4" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Fall Sowing Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
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 4a
📆 Growing Season
133 days in Blaine County
Growing Tips for Kohlrabi in Blaine County
Direct sow Kohlrabi outdoors after May 14 in Blaine 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
Check more plant combinations with our Companion Planting Checker →
Kohlrabi in Other Locations
Frequently Asked Questions
When should I plant Kohlrabi in Blaine County, MT?
Blaine County is in Zone 4a with an average last frost of May 14. Plan your Kohlrabi planting based on this frost date — see the calendar above for exact timing.
What planting zone is Blaine County, MT?
Blaine County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 14 and first fall frost is September 24.
Your Blaine County Garden Planner — Free
A 24-page printable planner built for Blaine 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.