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When to Plant Tatsoi in Powell County, MT

Powell County, Montana Zone 4b May

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

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

Avg. last frost June 6
Avg. first frost September 8
Soil temp (4") 40°F
Watering Moderate
Pest pressure Low
Daylight 14.8 hrs
  1. Direct-sow tatsoi

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

A few tasks this May that'll pay off in June
  • Transplants going out: 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.

Powell County, Montana is in USDA Zone 4b. The average last spring frost is June 6 and the first fall frost is September 8, giving you a growing season of approximately 94 days.

At an elevation of 5,514 feet, Powell County receives approximately 22.9 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Tatsoi to ensure they mature before fall.

Powell County, MT (Zone 4b) Very short season
94 days
Last Spring Frost June 6
94 growing days
First Fall Frost September 8

Powell County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (33 days to spare)
Start indoors: Apr 8 Transplant: May 20 🍅 Harvest: Jun 24 – Jul 29
Recommended (50%) ✓ Fits season (24 days to spare)
Start indoors: Apr 25 Transplant: Jun 6 🍅 Harvest: Jul 11 – Aug 15
Safe Start (90%) ✓ Fits season (33 days to spare)
Start indoors: May 9 Transplant: Jun 20 🍅 Harvest: Jul 25 – Aug 29

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 Powell County

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

Soil pH

Your soil pH (6.5–8.2) overlaps with Tatsoi's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). 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 94-day season

Sow every 4 weeks. Last sowing by Jul 20 to harvest before frost.

For a dedicated fall crop, sow by Jun 16.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 1.6" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 3" 0" ❄️ Dormant
Jun 4.3" 1.4" 2.9" 🚿 Regular watering
Jul 4.3" 2.1" 2.2" 🚿 Regular watering
Aug 4.3" 2.2" 2.1" 💧 Light watering
Sep 4.3" 1.8" 2.5" 🚿 Regular watering
Oct 2.1" 0" ❄️ Dormant
Nov 1.7" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Powell 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 ~552 GDD — county provides 1,222 GDD Excellent fit

Tatsoi Planting Timeline — Powell County, MT

Tatsoi Planting Calendar

Activity When Date Range
Start Indoors April 25 Apr 25 – May 9
Transplant Outdoors June 6 Jun 6 – Jun 20
Direct Sow May 30 May 30 – Jun 20
Harvest July 11 Jul 11 – Aug 15
Fall Sowing June 16 Jun 16 – Jun 30

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

94 days in Powell County

Growing Tips for Tatsoi in Powell County

Direct sow Tatsoi outdoors after June 06 in Powell 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.

Powell 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 Powell County, MT?

Powell County is in Zone 4b with an average last frost of June 6. Plan your Tatsoi planting based on this frost date — see the calendar above for exact timing.

What planting zone is Powell County, MT?

Powell County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is June 6 and first fall frost is September 8.

🌱

Your Powell County Garden Planner — Free

A 24-page printable planner built for Powell 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 Powell 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.