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When to Plant Potatoes in Millard County, UT

Millard County, Utah Zone 6a May

Your May planting checklist for Millard County, Utah

A quick May briefing for Millard County, Utah gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 16
Avg. first frost September 30
Soil temp (4") 38°F
Watering High
Pest pressure Low
Daylight 14.1 hrs
  1. Plant out potatoes

    Frost risk is low now in Millard County, Utah. If you've been covering beds overnight, you can stop.

  2. Sow potatoes where they'll grow

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

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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.

Millard County, Utah is in USDA Zone 6a. The average last spring frost is May 16 and the first fall frost is September 30, giving you a growing season of approximately 137 days.

At an elevation of 6,525 feet, Millard County receives approximately 24 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Potatoes to ensure they mature before fall.

Millard County, UT (Zone 6a) Short season
137 days
Last Spring Frost May 16
137 growing days
First Fall Frost September 30

Millard County Soil Profile

Soil Type

Loam

Soil pH

6.5-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 12 Transplant: May 21 🍅 Harvest: Jul 30 – Oct 8
Recommended (50%) ✗ May not fit
Start indoors: Mar 21 Transplant: May 30 🍅 Harvest: Aug 8 – Oct 17
Safe Start (90%) ✗ May not fit
Start indoors: Apr 14 Transplant: Jun 23 🍅 Harvest: Sep 1 – Nov 10

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 Millard County

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

Soil pH

Your soil pH (6.5–8.0) is more alkaline than Potatoes prefers (5.0–6.5). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Potatoes.

How to Plant Potatoes

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

Succession Planting Potatoes

2
successive plantings in your 137-day season

Sow every 8 weeks. Last sowing by Jun 02 to harvest before frost.

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 387 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 1.8" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2.7" 0" ❄️ Dormant
May 4.3" 2.7" 1.6" 💧 Light watering
Jun 4.3" 1.7" 2.6" 🚿 Regular watering
Jul 4.3" 2.1" 2.2" 🚿 Regular watering
Aug 4.3" 2.2" 2.1" 💧 Light watering
Sep 4.3" 2" 2.3" 🚿 Regular watering
Oct 2.2" 0" ❄️ Dormant
Nov 1.6" 0" ❄️ Dormant
Dec 1.5" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Millard 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 ~1,235 GDD — county provides 1,781 GDD Excellent fit

Potatoes Planting Timeline — Millard County, UT

Potatoes Planting Calendar

Activity When Date Range
Start Indoors March 21 Mar 21 – Apr 4
Transplant Outdoors May 30 May 30 – Jun 13
Direct Sow May 23 May 23 – Jun 13
Harvest August 8 Aug 8 – Oct 17

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors
May Transplant Outdoors 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 · 1-2 times/week

📅 Days to Maturity

70–120 days

🧪 Soil pH

Needs 5–6.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6a

📆 Growing Season

137 days in Millard County

Growing Tips for Potatoes in Millard County

Direct sow Potatoes outdoors after May 16 in Millard 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.

Millard County receives only 24" of rain annually. Potatoes needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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.

Recommended Potatoes Varieties for Millard County

Early-maturing potatoes for your season

Yukon Gold (65d) Red Norland (70d) Irish Cobbler (70d)

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 Millard County, UT?

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

What planting zone is Millard County, UT?

Millard County, Utah is in USDA Hardiness Zone 6a. The average last spring frost is May 16 and first fall frost is September 30.

🌱

Your Millard County Garden Planner — Free

A 24-page printable planner built for Millard County (Zone 6a). 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 Millard County, UT. 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.