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When to Plant Tatsoi in Broadwater County, MT

Broadwater County, Montana Zone 5a May

Your May gardening checklist

Each item below is timed to Broadwater County, Montana's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 20
Avg. first frost September 20
Soil temp (4") 30°F
Watering High
Pest pressure Low
Daylight 14.8 hrs
  1. Harden off and plant tatsoi

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

  2. Scatter tatsoi into prepared beds

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

Get ahead of June
  • Starting indoors: tatsoi
  • First harvests: 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.

Broadwater County, Montana is in USDA Zone 5a. The average last spring frost is May 20 and the first fall frost is September 20, giving you a growing season of approximately 123 days.

At an elevation of 7,806 feet, Broadwater County receives approximately 17.4 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. With low rainfall, drip irrigation is essential for growing Tatsoi successfully. Mulch heavily to conserve soil moisture.

Broadwater County, MT (Zone 5a) Short season
123 days
Last Spring Frost May 20
123 growing days
First Fall Frost September 20
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Broadwater County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (55 days to spare)
Start indoors: Apr 5 Transplant: May 10 🍅 Harvest: Jun 14 – Jul 19
Recommended (50%) ✓ Fits season (53 days to spare)
Start indoors: Apr 15 Transplant: May 20 🍅 Harvest: Jun 24 – Jul 29
Safe Start (90%) ✓ Fits season (44 days to spare)
Start indoors: May 12 Transplant: Jun 16 🍅 Harvest: Jul 21 – Aug 25

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 Broadwater County

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

Soil pH

Your soil pH (6.6–8.1) overlaps with Tatsoi's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Broadwater 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 10 weeks before your first frost date for a fall harvest.

Succession Planting Tatsoi

4
successive plantings in your 123-day season

Sow every 4 weeks. Last sowing by Aug 01 to harvest before frost.

For a dedicated fall crop, sow by Jul 12.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 533 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 1.3" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 1.7" 0" ❄️ Dormant
May 4.3" 2" 2.3" 🚿 Regular watering
Jun 4.3" 1.2" 3.1" 🚿 Regular watering
Jul 4.3" 1.7" 2.6" 🚿 Regular watering
Aug 4.3" 1.6" 2.7" 🚿 Regular watering
Sep 4.3" 1.5" 2.8" 🚿 Regular watering
Oct 1.5" 0" ❄️ Dormant
Nov 1.2" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Broadwater 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 1,506 GDD Excellent fit

Tatsoi Planting Timeline — Broadwater County, MT

Tatsoi Planting Calendar

Activity When Date Range
Start Indoors April 15 Apr 15 – Apr 29
Transplant Outdoors May 20 May 20 – Jun 3
Direct Sow May 6 May 6 – May 27
Harvest June 24 Jun 24 – Jul 29
Fall Sowing July 12 Jul 12 – Jul 26

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 Harvest
July Fall Sowing Harvest
August
September
October
November
December
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

123 days in Broadwater County

Growing Tips for Tatsoi in Broadwater County

Direct sow Tatsoi outdoors after May 20 in Broadwater 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.

Broadwater County receives only 17" 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 Broadwater County, MT?

Broadwater County is in Zone 5a with an average last frost of May 20. Plan your Tatsoi planting based on this frost date — see the calendar above for exact timing.

What planting zone is Broadwater County, MT?

Broadwater County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is May 20 and first fall frost is September 20.

🌱

Your Broadwater County Garden Planner — Free

A 24-page printable planner built for Broadwater County (Zone 5a). 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 Broadwater 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.