Blog

When to Plant Mizuna in Putnam County, MO

Putnam County, Missouri Zone 5b May

Your May game plan for Putnam County, Missouri

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

Avg. last frost April 18
Avg. first frost October 16
Soil temp (4") 58°F
Watering Low
Pest pressure Low
Daylight 14.2 hrs
  1. Get mizuna seeds going inside

    Your window is short. These crops want several weeks of indoor growth before they go outside.

  2. Start harvesting mizuna

    If you can't use it all right away, check the food-preservation section of your planner.

To set up a strong June, finish these tasks
  • First harvests: 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.

Putnam County, Missouri is in USDA Zone 5b. The average last spring frost is April 18 and the first fall frost is October 16, giving you a growing season of approximately 181 days.

At an elevation of 1,185 feet, Putnam County receives approximately 40.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Mizuna to ensure they mature before fall.

Putnam County, MO (Zone 5b) Moderate season
181 days
Last Spring Frost April 18
181 growing days
First Fall Frost October 16

Putnam County Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (118 days to spare)
Start indoors: Mar 9 Transplant: Apr 13 🍅 Harvest: May 18 – Jun 15
Recommended (50%) ✓ Fits season (118 days to spare)
Start indoors: Mar 14 Transplant: Apr 18 🍅 Harvest: May 23 – Jun 20
Safe Start (90%) ✓ Fits season (118 days to spare)
Start indoors: Mar 29 Transplant: May 3 🍅 Harvest: Jun 7 – Jul 5

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 Putnam County

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

Soil pH

Your soil pH (5.6–7.0) overlaps with Mizuna's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.1%). 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

7
successive plantings in your 181-day season

Sow every 3.4 weeks. Last sowing by Sep 01 to harvest before frost.

For a dedicated fall crop, sow by Aug 07.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 112 gal / 100 sq ft

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 1.7" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.9" 0" ❄️ Dormant
Apr 4.3" 4.1" 0.2" 💧 Light watering
May 4.3" 4.4" 0" ✅ Rainfall sufficient
Jun 4.3" 5.4" 0" ✅ Rainfall sufficient
Jul 4.3" 3.9" 0.4" 💧 Light watering
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 3.6" 0.7" 💧 Light watering
Oct 4.3" 3.2" 1.1" 💧 Light watering
Nov 2.7" 0" ❄️ Dormant
Dec 2.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Putnam 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 ~459 GDD — county provides 2,217 GDD Excellent fit

Mizuna Planting Timeline — Putnam County, MO

Mizuna Planting Calendar

Activity When Date Range
Start Indoors March 14 Mar 14 – Mar 28
Transplant Outdoors April 18 Apr 18 – May 2
Direct Sow April 4 Apr 4 – Apr 25
Harvest May 23 May 23 – Jun 20
Fall Sowing August 7 Aug 7 – Aug 21

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

30–45 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

181 days in Putnam County

Growing Tips for Mizuna in Putnam County

Direct sow Mizuna outdoors after April 18 in Putnam County when soil has warmed and frost danger has passed.

Your generous 181.0-day season in Putnam County allows multiple plantings of Mizuna. Sow every 15.0 days for continuous harvest.

Common pests for Mizuna 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. 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 Putnam County, MO?

Putnam County is in Zone 5b with an average last frost of April 18. Plan your Mizuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Putnam County, MO?

Putnam County, Missouri is in USDA Hardiness Zone 5b. The average last spring frost is April 18 and first fall frost is October 16.

🌱

Your Putnam County Garden Planner — Free

A 24-page printable planner built for Putnam County (Zone 5b). 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 Putnam County, MO. 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.