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When to Plant Bok Choy in Deer Lodge County, MT

Deer Lodge County, Montana Zone 5a May

Your May gardening checklist

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

Avg. last frost June 15
Avg. first frost September 7
Soil temp (4") 33°F
Watering High
Pest pressure Low
Daylight 14.8 hrs
A few tasks this May that'll pay off in June
  • Transplants going out: bok choy
  • Direct-sowing: bok choy
  • Fall sowing: bok choy

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Bok choy is a Chinese cabbage variety with crisp white stalks and dark green leaves. It is a fast-growing cool-season crop ideal for stir-fries and soups.

Deer Lodge County, Montana is in USDA Zone 5a. The average last spring frost is June 15 and the first fall frost is September 7, giving you a growing season of approximately 84 days.

At an elevation of 6,928 feet, Deer Lodge County receives approximately 16.8 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Bok Choy to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Bok Choy successfully. Mulch heavily to conserve soil moisture.

Deer Lodge County, MT (Zone 5a) Very short season
84 days
Last Spring Frost June 15
84 growing days
First Fall Frost September 7
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Deer Lodge County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (8 days to spare)
Start indoors: May 5 Transplant: Jun 9 🍅 Harvest: Jul 21 – Aug 25
Recommended (50%) ✓ Fits season (7 days to spare)
Start indoors: May 11 Transplant: Jun 15 🍅 Harvest: Jul 27 – Aug 31
Safe Start (90%) ✓ Fits season (13 days to spare)
Start indoors: May 19 Transplant: Jun 23 🍅 Harvest: Aug 4 – Sep 8

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 Deer Lodge County

How your county's soil matches Bok Choy's growing requirements.

Soil pH

Your soil pH (6.6–8.2) overlaps with Bok Choy's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Deer Lodge County is excellent for Bok Choy — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Bok Choy.

How to Plant Bok Choy

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Bok Choy

2
successive plantings in your 84-day season

Sow every 4.6 weeks. Last sowing by Jul 09 to harvest before frost.

For a dedicated fall crop, sow by Jun 29.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.8″/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 Bok Choy

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

Month Bok Choy Needs Rainfall You Supplement Action
Jan 1.2" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1.4" 0" ❄️ Dormant
Apr 1.9" 0" ❄️ Dormant
May 1.9" 0" ❄️ Dormant
Jun 3" 1.2" 1.8" 🚿 Regular watering
Jul 3" 1.4" 1.6" 🚿 Regular watering
Aug 3" 1.9" 1.1" 💧 Light watering
Sep 3" 1.3" 1.7" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 1.1" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

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

Bok Choy 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.

Bok Choy needs ~538 GDD — county provides 903 GDD Excellent fit

Bok Choy Planting Timeline — Deer Lodge County, MT

Bok Choy Planting Calendar

Activity When Date Range
Start Indoors May 11 May 11 – May 25
Transplant Outdoors June 15 Jun 15 – Jun 29
Direct Sow June 1 Jun 1 – Jun 22
Harvest July 27 Jul 27 – Aug 31
Fall Sowing June 29 Jun 29 – Jul 13

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

40–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

84 days in Deer Lodge County

Growing Tips for Bok Choy in Deer Lodge County

Direct sow Bok Choy outdoors after June 15 in Deer Lodge County when soil has warmed and frost danger has passed.

Common pests for Bok Choy 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 for best results. Keep soil consistently moist. Harvest whole heads or cut outer leaves for a cut-and-come-again approach.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Bok Choy in Deer Lodge County, MT?

Deer Lodge County is in Zone 5a with an average last frost of June 15. Plan your Bok Choy planting based on this frost date — see the calendar above for exact timing.

What planting zone is Deer Lodge County, MT?

Deer Lodge County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is June 15 and first fall frost is September 7.

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Your Deer Lodge County Garden Planner — Free

A 24-page printable planner built for Deer Lodge 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 Deer Lodge 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.