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When to plant Potatoes in Marshall County, MN

In Marshall County, Potatoes is a single-season spring crop — there's no second fall window. Plant May 25–June 15 for an 70–120-day harvest, finishing well before the October 2 first frost.

When to Plant Potatoes in Marshall County, MN

Potatoes
Marshall County, Minnesota Zone 3b July

Your July gardening checklist

We've pulled the most time-sensitive tasks for Marshall County, Minnesota this July and put them front and centre. Tackle them in order.

Avg. last frost May 11
Avg. first frost October 2
Soil temp (4") 68°F
Watering Low
Pest pressure Moderate
Daylight 15.5 hrs
  1. Get potatoes seeds going inside

    Label every cell. You will absolutely forget which is which otherwise.

August prep starts now
  • First harvests: potatoes

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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.

Marshall County, Minnesota is in USDA Zone 3b. The average last spring frost is May 11 and the first fall frost is October 2, giving you a growing season of approximately 144 days.

At an elevation of 1,303 feet, Marshall County receives approximately 33.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Potatoes to ensure they mature before fall.

Marshall County, MN (Zone 3b) Short season
144 days
Last Spring Frost May 11
144 growing days
First Fall Frost October 2

Marshall County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.3

Drainage

Well Drained

Potatoes Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 5 Transplant: May 28 🍅 Harvest: Aug 6 – Oct 1
Recommended (50%) ✗ May not fit
Start indoors: Mar 9 Transplant: Jun 1 🍅 Harvest: Aug 10 – Oct 5
Safe Start (90%) ✗ May not fit
Start indoors: Mar 21 Transplant: Jun 13 🍅 Harvest: Aug 22 – Oct 17

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 Marshall County

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

Soil pH

Your soil pH (5.8–7.3) is more alkaline than Potatoes prefers (5.0–6.5). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.2%) — Potatoes will thrive.

How to Plant Potatoes

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

Succession Planting Potatoes

2
successive plantings in your 144-day season

Sow every 8 weeks. Last sowing by Jun 04 to harvest before frost.

Potatoes Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 31 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 1.2" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 3.2" 0" ❄️ Dormant
May 4.3" 4.3" 0" ✅ Rainfall sufficient
Jun 4.3" 4.2" 0.1" 💧 Light watering
Jul 4.3" 3.8" 0.5" 💧 Light watering
Aug 4.3" 3" 1.3" 💧 Light watering
Sep 4.3" 3" 1.3" 💧 Light watering
Oct 4.3" 2.6" 1.7" 💧 Light watering
Nov 2.2" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Marshall 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 ~1,021 GDD — county provides 1,548 GDD Excellent fit

Potatoes Planting Timeline — Marshall County, MN

Potatoes Planting Calendar

Activity When Date Range
Start Indoors March 9 Mar 9 – Mar 23
Transplant Outdoors June 1 Jun 1 – Jun 15
Direct Sow May 25 May 25 – Jun 15
Harvest August 10 Aug 10 – Oct 5

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

70–120 days

🧪 Soil pH

Needs 5–6.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 3b

📆 Growing Season

144 days in Marshall County

Growing Tips for Potatoes in Marshall County

Direct sow Potatoes outdoors after May 11 in Marshall 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 Marshall County, MN?

Marshall County is in Zone 3b with an average last frost of May 11. Plan your Potatoes planting based on this frost date — see the calendar above for exact timing.

What planting zone is Marshall County, MN?

Marshall County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is May 11 and first fall frost is October 2.

When should I plant Potatoes in Marshall County, MN?

In Marshall County, MN, plant Potatoes after the last frost (around May 11) and before the first frost (around October 2). Best results when soil holds above 50°F.

What growing zone is Marshall County, MN for Potatoes?

Marshall County sits in USDA Zone 3b. Potatoes grows reliably in zones 3a through 10b, so it's a good fit here.

Can Potatoes grow in Marshall County's climate?

Yes — Potatoes grows well in Marshall County's temperate climate. Marshall County averages a 144-day frost-free season, with last frost around May 11 and first frost around October 2.

🌱

Your Marshall County Garden Planner — Free

A 22-page printable planner built for Marshall County (Zone 3b). 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 Marshall County, MN. Local conditions may vary. Last updated: July 2026.

Sources & credits

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