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When to Plant Tatsoi in Toole County, MT

Toole County, Montana Zone 4a May

Your May planting checklist for Toole County, Montana

May is a pivotal month for Toole County, Montana gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 24
Avg. first frost September 17
Soil temp (4") 30°F
Watering High
Pest pressure Low
Daylight 15 hrs
  1. Get tatsoi in the ground

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

  2. Plant tatsoi from seed, right in the garden

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

Get ahead of June
  • First harvests: tatsoi
  • Fall sowing: tatsoi

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Tatsoi is a compact Asian green forming beautiful rosettes of dark, spoon-shaped leaves with a mild mustard flavor. It is extremely cold-hardy and versatile.

Toole County, Montana is in USDA Zone 4a. The average last spring frost is May 24 and the first fall frost is September 17, giving you a growing season of approximately 116 days.

At an elevation of 7,194 feet, Toole County receives approximately 23.3 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Tatsoi to ensure they mature before fall.

Toole County, MT (Zone 4a) Short season
116 days
Last Spring Frost May 24
116 growing days
First Fall Frost September 17

Toole County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (44 days to spare)
Start indoors: Apr 6 Transplant: May 18 🍅 Harvest: Jun 22 – Jul 27
Recommended (50%) ✓ Fits season (46 days to spare)
Start indoors: Apr 12 Transplant: May 24 🍅 Harvest: Jun 28 – Aug 2
Safe Start (90%) ✓ Fits season (35 days to spare)
Start indoors: May 3 Transplant: Jun 14 🍅 Harvest: Jul 19 – Aug 23

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 Toole County

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

Soil pH

Your soil pH (6.8–8.2) overlaps with Tatsoi's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Tatsoi

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

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

Succession Planting Tatsoi

3
successive plantings in your 116-day season

Sow every 4 weeks. Last sowing by Jul 29 to harvest before frost.

For a dedicated fall crop, sow by Jun 25.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 194 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Tatsoi

Tatsoi needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Tatsoi Needs Rainfall You Supplement Action
Jan 1.9" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2.3" 0" ❄️ Dormant
May 4.3" 2.4" 1.9" 💧 Light watering
Jun 4.3" 1.5" 2.8" 🚿 Regular watering
Jul 4.3" 2.2" 2.1" 💧 Light watering
Aug 4.3" 2.3" 2" 💧 Light watering
Sep 4.3" 2.2" 2.1" 💧 Light watering
Oct 2" 0" ❄️ Dormant
Nov 1.8" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

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

Tatsoi 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.

Tatsoi needs ~521 GDD — county provides 1,421 GDD Excellent fit

Tatsoi Planting Timeline — Toole County, MT

Tatsoi Planting Calendar

Activity When Date Range
Start Indoors April 12 Apr 12 – Apr 26
Transplant Outdoors May 24 May 24 – Jun 7
Direct Sow May 17 May 17 – Jun 7
Harvest June 28 Jun 28 – Aug 2
Fall Sowing June 25 Jun 25 – Jul 9

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

116 days in Toole County

Growing Tips for Tatsoi in Toole County

Direct sow Tatsoi outdoors after May 24 in Toole County when soil has warmed and frost danger has passed.

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

Toole County receives only 23" of rain annually. Tatsoi needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow in spring or fall. Tatsoi tolerates frost down to 15F. Harvest outer leaves or cut whole rosettes. Excellent in salads, stir-fries, or lightly wilted.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Tatsoi in Toole County, MT?

Toole County is in Zone 4a with an average last frost of May 24. Plan your Tatsoi planting based on this frost date — see the calendar above for exact timing.

What planting zone is Toole County, MT?

Toole County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 24 and first fall frost is September 17.

🌱

Your Toole County Garden Planner — Free

A 24-page printable planner built for Toole 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.

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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 Toole 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.