Blog

When to Plant Mizuna in Silver Bow County, MT

Silver Bow County, Montana Zone 5a May

This month in Silver Bow County, Montana

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

Avg. last frost June 15
Avg. first frost September 7
Soil temp (4") 37°F
Watering High
Pest pressure Low
Daylight 14.7 hrs
Get ahead of June
  • Transplants going out: mizuna
  • Direct-sowing: mizuna
  • Fall sowing: mizuna

Instant PDF download. No spam, unsubscribe any time.

Mizuna is a mild-flavored Japanese mustard green with feathery, deeply serrated leaves. It is fast-growing and makes an excellent addition to salads and stir-fries.

Silver Bow 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 5,305 feet, Silver Bow County receives approximately 14.3 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Mizuna to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Mizuna successfully. Mulch heavily to conserve soil moisture.

Silver Bow County, MT (Zone 5a) Very short season
84 days
Last Spring Frost June 15
84 growing days
First Fall Frost September 7

Silver Bow County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (22 days to spare)
Start indoors: May 5 Transplant: Jun 9 🍅 Harvest: Jul 14 – Aug 11
Recommended (50%) ✓ Fits season (21 days to spare)
Start indoors: May 11 Transplant: Jun 15 🍅 Harvest: Jul 20 – Aug 17
Safe Start (90%) ✓ Fits season (27 days to spare)
Start indoors: May 19 Transplant: Jun 23 🍅 Harvest: Jul 28 – 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 Silver Bow County

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

Soil pH

Your soil pH (6.6–8.3) overlaps with Mizuna's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Silver Bow County is excellent for Mizuna — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

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

How to Plant Mizuna

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 Mizuna

3
successive plantings in your 84-day season

Sow every 3.4 weeks. Last sowing by Jul 24 to harvest before frost.

For a dedicated fall crop, sow by Jun 29.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 256 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Mizuna

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

Month Mizuna Needs Rainfall You Supplement Action
Jan 1.1" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 1.4" 0" ❄️ Dormant
May 1.5" 0" ❄️ Dormant
Jun 4.3" 0.9" 3.4" 🚿 Regular watering
Jul 4.3" 1.1" 3.2" 🚿 Regular watering
Aug 4.3" 1.8" 2.5" 🚿 Regular watering
Sep 4.3" 1.1" 3.2" 🚿 Regular watering
Oct 1.1" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

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

Mizuna 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.

Mizuna needs ~488 GDD — county provides 1,092 GDD Excellent fit

Mizuna Planting Timeline — Silver Bow County, MT

Mizuna 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 20 Jul 20 – Aug 17
Fall Sowing June 29 Jun 29 – Jul 13

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

30–45 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

84 days in Silver Bow County

Growing Tips for Mizuna in Silver Bow County

Direct sow Mizuna outdoors after June 15 in Silver Bow County when soil has warmed and frost danger has passed.

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

Silver Bow County receives only 14" of rain annually. Mizuna needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow in spring or fall. Harvest outer leaves as needed for a cut-and-come-again approach. Mizuna is one of the most cold-tolerant Asian greens.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mizuna in Silver Bow County, MT?

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

What planting zone is Silver Bow County, MT?

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

🌱

Your Silver Bow County Garden Planner — Free

A 24-page printable planner built for Silver Bow 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Silver Bow 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.