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When to Plant Sorrel in Slope County, ND

Slope County, North Dakota Zone 4b May

This month in Slope County, North Dakota

Each item below is timed to Slope County, North Dakota's frost dates and soil temperatures. Skip nothing, stress about nothing.

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. Set out sorrel seedlings

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

  2. Put sorrel seeds straight in the ground

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

To set up a strong June, finish these tasks
  • Starting indoors: sorrel
  • First harvests: sorrel

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Sorrel is a perennial herb with tangy, lemon-flavored arrow-shaped leaves. It is one of the first greens to emerge in spring and is used in soups and salads.

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 Sorrel 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

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 (32 days to spare)
Start indoors: Mar 31 Transplant: May 5 🍅 Harvest: Jun 16 – Aug 18
Recommended (50%) ✓ Fits season (34 days to spare)
Start indoors: Apr 3 Transplant: May 8 🍅 Harvest: Jun 19 – Aug 21
Safe Start (90%) ✓ Fits season (29 days to spare)
Start indoors: Apr 20 Transplant: May 25 🍅 Harvest: Jul 6 – Sep 7

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 Sorrel's growing requirements.

Soil pH

Your soil pH (6.7–7.6) is more alkaline than Sorrel prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Sorrel.

Organic Matter

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

How to Plant Sorrel

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

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

Succession Planting Sorrel

3
successive plantings in your 132-day season

Sow every 4.6 weeks. Last sowing by Jul 26 to harvest before frost.

For a dedicated fall crop, sow by Jul 02.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 424 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Sorrel

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

Month Sorrel 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 4.3" 3.3" 1" 💧 Light watering
Jun 4.3" 2.3" 2" 💧 Light watering
Jul 4.3" 3.1" 1.2" 💧 Light watering
Aug 4.3" 3" 1.3" 💧 Light watering
Sep 4.3" 2.3" 2" 💧 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.

Sorrel 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.

Sorrel needs ~500 GDD — county provides 1,320 GDD Excellent fit

Sorrel Planting Timeline — Slope County, ND

Sorrel Planting Calendar

Activity When Date Range
Start Indoors April 3 Apr 3 – Apr 17
Transplant Outdoors May 8 May 8 – May 22
Direct Sow May 8 May 8 – May 29
Harvest June 19 Jun 19 – Aug 21
Fall Sowing July 2 Jul 2 – Jul 16

Plant 0.5" deep · 8" 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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

40–60 days

🧪 Soil pH

Needs 5.5–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

132 days in Slope County

Growing Tips for Sorrel in Slope County

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

General growing tips

Direct sow in early spring or fall. Remove flower stalks promptly to encourage leaf production. Divide clumps every 3-4 years. Young leaves have the best flavor.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sorrel in Slope County, ND?

Slope County is in Zone 4b with an average last frost of May 15. Plan your Sorrel 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.