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When to Plant Potatoes in St. Francois County, MO

St. Francois County, Missouri Zone 6b April

Your April planting checklist for St. Francois County, Missouri

We've pulled the most time-sensitive tasks for St. Francois County, Missouri this April and put them front and centre. Tackle them in order.

Avg. last frost April 16
Avg. first frost October 21
Soil temp (4") 53°F
Watering Low
Pest pressure Low
Daylight 13 hrs
  1. Plant out potatoes

    Frost risk is low now in St. Francois County, Missouri. If you've been covering beds overnight, you can stop.

  2. Sow potatoes where they'll grow

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

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Potatoes are a versatile staple crop that produces tubers underground. They come in hundreds of varieties with varying colors, textures, and maturity dates.

St. Francois County, Missouri is in USDA Zone 6b. The average last spring frost is April 16 and the first fall frost is October 21, giving you a growing season of approximately 188 days.

At an elevation of 808 feet, St. Francois County receives approximately 41 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91°F, providing good warmth for Potatoes during the growing season.

St. Francois County, MO (Zone 6b) Moderate season
188 days
Last Spring Frost April 16
188 growing days
First Fall Frost October 21

St. Francois County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (34 days to spare)
Start indoors: Feb 11 Transplant: Apr 22 🍅 Harvest: Jul 1 – Sep 9
Recommended (50%) ✓ Fits season (34 days to spare)
Start indoors: Feb 19 Transplant: Apr 30 🍅 Harvest: Jul 9 – Sep 17
Safe Start (90%) ✓ Fits season (36 days to spare)
Start indoors: Mar 4 Transplant: May 13 🍅 Harvest: Jul 22 – Sep 30

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 St. Francois County

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

Soil pH

Your soil pH (5.3–7.0) overlaps with Potatoes's range (5.0–6.5), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Potatoes.

Organic Matter

Organic matter is moderate (2.9%). Annual compost additions will help Potatoes.

How to Plant Potatoes

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

Succession Planting Potatoes

3
successive plantings in your 188-day season

Sow every 8 weeks. Last sowing by Jun 23 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/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 Potatoes

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

Month Potatoes Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 4.3" 4.3" 0" ✅ Rainfall sufficient
May 4.3" 5.4" 0" ✅ Rainfall sufficient
Jun 4.3" 5" 0" ✅ Rainfall sufficient
Jul 4.3" 4.2" 0.1" 💧 Light watering
Aug 4.3" 4.6" 0" ✅ Rainfall sufficient
Sep 4.3" 3.1" 1.2" 💧 Light watering
Oct 4.3" 3.6" 0.7" 💧 Light watering
Nov 2.9" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in St. Francois County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Potatoes 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.

Potatoes needs ~1,734 GDD — county provides 3,431 GDD Excellent fit

Potatoes Planting Timeline — St. Francois County, MO

Potatoes Planting Calendar

Activity When Date Range
Start Indoors February 19 Feb 19 – Mar 5
Transplant Outdoors April 30 Apr 30 – May 14
Direct Sow April 23 Apr 23 – May 14
Harvest July 9 Jul 9 – Sep 17

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

70–120 days

🧪 Soil pH

Needs 5–6.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

188 days in St. Francois County

Growing Tips for Potatoes in St. Francois County

Direct sow Potatoes outdoors after April 16 in St. Francois County when soil has warmed and frost danger has passed.

Common pests for Potatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Plant seed potatoes (not grocery store potatoes) 4 inches deep in spring. Hill soil around stems as plants grow to prevent greening. Stop watering when plants die back.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Cucumber
  • Squash Summer

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Potatoes in St. Francois County, MO?

St. Francois County is in Zone 6b with an average last frost of April 16. Plan your Potatoes planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Francois County, MO?

St. Francois County, Missouri is in USDA Hardiness Zone 6b. The average last spring frost is April 16 and first fall frost is October 21.

🌱

Your St. Francois County Garden Planner — Free

A 24-page printable planner built for St. Francois County (Zone 6b). 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 St. Francois County, MO. Local conditions may vary. Last updated: April 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.