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When to Plant Sorrel in Carter County, MT

Carter County, Montana Zone 4b May

Your May game plan for Carter County, Montana

We've pulled the most time-sensitive tasks for Carter County, Montana this May and put them front and centre. Tackle them in order.

Avg. last frost May 15
Avg. first frost September 22
Soil temp (4") 30°F
Watering High
Pest pressure Low
Daylight 14.7 hrs
  1. Transplant sorrel outside

    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. Scatter sorrel into prepared beds

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

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

Carter County, Montana is in USDA Zone 4b. The average last spring frost is May 15 and the first fall frost is September 22, giving you a growing season of approximately 130 days.

At an elevation of 7,923 feet, Carter County receives approximately 19.8 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Sorrel to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Sorrel successfully. Mulch heavily to conserve soil moisture.

Carter County, MT (Zone 4b) Short season
130 days
Last Spring Frost May 15
130 growing days
First Fall Frost September 22
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Carter County Soil Profile

Soil Type

Loam

Soil pH

6.4-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (33 days to spare)
Start indoors: Mar 30 Transplant: May 4 🍅 Harvest: Jun 15 – Aug 17
Recommended (50%) ✓ Fits season (32 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 21 Transplant: May 26 🍅 Harvest: Jul 7 – Sep 8

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 Carter County

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

Soil pH

Your soil pH (6.4–8.2) is more alkaline than Sorrel prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help Sorrel.

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 130-day season

Sow every 4.6 weeks. Last sowing by Jul 24 to harvest before frost.

For a dedicated fall crop, sow by Jun 30.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 500 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 1.4" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2.2" 0" ❄️ Dormant
May 4.3" 2.4" 1.9" 💧 Light watering
Jun 4.3" 1.4" 2.9" 🚿 Regular watering
Jul 4.3" 1.6" 2.7" 🚿 Regular watering
Aug 4.3" 1.9" 2.4" 🚿 Regular watering
Sep 4.3" 1.4" 2.9" 🚿 Regular watering
Oct 1.7" 0" ❄️ Dormant
Nov 1.3" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Carter 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 ~538 GDD — county provides 1,397 GDD Excellent fit

Sorrel Planting Timeline — Carter County, MT

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 June 30 Jun 30 – Jul 14

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 Fall Sowing Harvest
July Fall Sowing Harvest
August Harvest
September
October
November
December
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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

130 days in Carter County

Growing Tips for Sorrel in Carter County

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

Carter County receives only 20" of rain annually. Sorrel needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Carter County, MT?

Carter 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 Carter County, MT?

Carter County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 15 and first fall frost is September 22.

🌱

Your Carter County Garden Planner — Free

A 24-page printable planner built for Carter 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 Carter County, MT. 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.