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When to Plant Lettuce in Slope County, ND

Slope County, North Dakota Zone 4b May

Slope County, North Dakota gardeners: here's your May plan

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Slope County, North Dakota.

Avg. last frost May 15
Avg. first frost September 24
Soil temp (4") 52°F
Watering Moderate
Pest pressure Low
Daylight 14.8 hrs
  1. Time to transplant lettuce

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Sow lettuce where they'll grow

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

Before June arrives, get these ready
  • Starting indoors: lettuce
  • First harvests: lettuce

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Lettuce is a fast-growing cool-season green available in leaf, romaine, butterhead, and crisphead types. It is the foundation of salads and one of the easiest crops to grow.

Slope County, North Dakota is in USDA Zone 4b. The average last spring frost is May 15 and the first fall frost is September 24, giving you a growing season of approximately 132 days.

At an elevation of 1,230 feet, Slope County receives approximately 31.4 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Lettuce to ensure they mature before fall.

Slope County, ND (Zone 4b) Short season
132 days
Last Spring Frost May 15
132 growing days
First Fall Frost September 24
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Slope County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (25 days to spare)
Start indoors: Mar 31 Transplant: May 12 🍅 Harvest: Jun 16 – Aug 25
Recommended (50%) ✓ Fits season (27 days to spare)
Start indoors: Apr 3 Transplant: May 15 🍅 Harvest: Jun 19 – Aug 28
Safe Start (90%) ✓ Fits season (22 days to spare)
Start indoors: Apr 20 Transplant: Jun 1 🍅 Harvest: Jul 6 – Sep 14

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 Slope County

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

Soil pH

Your soil pH (6.7–7.6) is more alkaline than Lettuce prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Lettuce.

Organic Matter

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

How to Plant Lettuce

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Lettuce

5
successive plantings in your 132-day season

Sow every 3.4 weeks. Last sowing by Jul 26 to harvest before frost.

For a dedicated fall crop, sow by Jul 02.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Lettuce

Lettuce needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Lettuce Needs Rainfall You Supplement Action
Jan 2.4" 0" ❄️ Dormant
Feb 1.9" 0" ❄️ Dormant
Mar 3.1" 0" ❄️ Dormant
Apr 2.9" 0" ❄️ Dormant
May 3" 3.3" 0" ✅ Rainfall sufficient
Jun 3" 2.3" 0.7" 💧 Light watering
Jul 3" 3.1" 0" ✅ Rainfall sufficient
Aug 3" 3" 0" ✅ Rainfall sufficient
Sep 3" 2.3" 0.7" 💧 Light watering
Oct 2.7" 0" ❄️ Dormant
Nov 2.3" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

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

Lettuce 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.

Lettuce needs ~450 GDD — county provides 1,320 GDD Excellent fit

Lettuce Planting Timeline — Slope County, ND

Lettuce Planting Calendar

Activity When Date Range
Start Indoors April 3 Apr 3 – Apr 17
Transplant Outdoors May 15 May 15 – May 29
Direct Sow May 8 May 8 – May 29
Harvest June 19 Jun 19 – Aug 28
Fall Sowing July 2 Jul 2 – Jul 16

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

30–60 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

132 days in Slope County

Growing Tips for Lettuce in Slope County

Direct sow Lettuce outdoors after May 15 in Slope County when soil has warmed and frost danger has passed.

Common pests for Lettuce in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

General growing tips

Sow seeds directly every 2 weeks for continuous harvest. Provide afternoon shade in warm weather to delay bolting. Harvest in the morning for crispest leaves.

Companion Planting

Good Companions

Avoid Planting Near

  • Celery

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Lettuce Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Let plants bolt and flower. Harvest seed heads when fluffy.
Storage Store airtight; viable 6 years at 35°F, under 45% humidity.

Very easy to save. Let a few plants bolt each season.

Frequently Asked Questions

When should I plant Lettuce in Slope County, ND?

Slope County is in Zone 4b with an average last frost of May 15. Plan your Lettuce planting based on this frost date — see the calendar above for exact timing.

What planting zone is Slope County, ND?

Slope County, North Dakota is in USDA Hardiness Zone 4b. The average last spring frost is May 15 and first fall frost is September 24.

🌱

Your Slope County Garden Planner — Free

A 24-page printable planner built for Slope County (Zone 4b). 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 Slope County, ND. 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.