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When to Plant Comfrey in Marshall County, OK

Marshall County, Oklahoma Zone 8a May

Top priorities for Marshall County, Oklahoma gardeners in May

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

Avg. last frost March 24
Avg. first frost November 12
Soil temp (4") 70°F
Watering Low
Pest pressure Moderate
Daylight 13.8 hrs
Before June arrives, get these ready
  • First harvests: comfrey

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Comfrey is a vigorous perennial herb valued as a dynamic accumulator of nutrients. Its leaves make excellent mulch, compost activator, and liquid fertilizer.

Marshall County, Oklahoma is in USDA Zone 8a. The average last spring frost is March 24 and the first fall frost is November 12, giving you a growing season of approximately 233 days.

At an elevation of 520 feet, Marshall County receives approximately 23.7 inches of rainfall annually with predominantly loam soil. Summer highs average 92°F, providing good warmth for Comfrey during the growing season.

Marshall County, OK (Zone 8a) Long season
233 days
Last Spring Frost March 24
233 growing days
First Fall Frost November 12
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Marshall County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (97 days to spare)
Transplant: Mar 18 🍅 Harvest: May 20 – Jul 29
Recommended (50%) ✓ Fits season (93 days to spare)
Transplant: Mar 31 🍅 Harvest: Jun 2 – Aug 11
Safe Start (90%) ✓ Fits season (90 days to spare)
Transplant: Apr 21 🍅 Harvest: Jun 23 – Sep 1

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 Comfrey's growing requirements.

Soil pH

Your soil pH (6.2–7.8) overlaps with Comfrey's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Comfrey.

Organic Matter

Organic matter is moderate (3.5%). Annual compost additions will help Comfrey.

How to Plant Comfrey

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

Succession Planting Comfrey

4
successive plantings in your 233-day season

Sow every 6.9 weeks. Last sowing by Aug 14 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.4″/week
You supply
1.1″/week
Watering frequency 2-3 times/week
Season total 2,172 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Comfrey

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

Month Comfrey Needs Rainfall You Supplement Action
Jan 0.5" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 4.3" 1.6" 2.7" 🚿 Regular watering
Apr 4.3" 2.3" 2" 💧 Light watering
May 4.3" 4" 0.3" 💧 Light watering
Jun 4.3" 3.4" 0.9" 💧 Light watering
Jul 4.3" 3" 1.3" 💧 Light watering
Aug 4.3" 2.8" 1.5" 💧 Light watering
Sep 4.3" 2.4" 1.9" 💧 Light watering
Oct 4.3" 1.3" 3" 🚿 Regular watering
Nov 4.3" 0.9" 3.4" 🚿 Regular watering
Dec 0.6" 0" ❄️ Dormant

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

Comfrey 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.

Comfrey needs ~1,425 GDD — county provides 4,427 GDD Excellent fit

Comfrey Planting Timeline — Marshall County, OK

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors March 31 Mar 31 – Apr 14
Harvest June 2 Jun 2 – Aug 11

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March Transplant Outdoors
April Transplant Outdoors
May
June Harvest
July Harvest
August Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 8a

📆 Growing Season

233 days in Marshall County

Growing Tips for Comfrey in Marshall County

Direct sow Comfrey outdoors after March 24 in Marshall County when soil has warmed and frost danger has passed.

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

General growing tips

Plant root cuttings 2 inches deep. Choose Bocking 14 variety to prevent self-seeding. Cut leaves 3-4 times per season for mulch or compost. Avoid planting near pathways as it spreads.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Comfrey in Marshall County, OK?

Marshall County is in Zone 8a with an average last frost of March 24. Plan your Comfrey planting based on this frost date — see the calendar above for exact timing.

What planting zone is Marshall County, OK?

Marshall County, Oklahoma is in USDA Hardiness Zone 8a. The average last spring frost is March 24 and first fall frost is November 12.

🌱

Your Marshall County Garden Planner — Free

A 24-page printable planner built for Marshall County (Zone 8a). 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, OK. 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.