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When to Plant Comfrey in Merced County, CA

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

Merced County, California is in USDA Zone 9a. The average last spring frost is February 24 and the first fall frost is November 28, giving you a growing season of approximately 277 days.

At an elevation of 269 feet, Merced County receives approximately 18.8 inches of rainfall annually with predominantly loam soil. Summer highs average 87ยฐF, providing good warmth for Comfrey during the growing season. With low rainfall, drip irrigation is essential for growing Comfrey successfully. Mulch heavily to conserve soil moisture.

Merced County, CA (Zone 9a) Year-round
277 days
Last Spring Frost February 24
277 growing days
First Fall Frost November 28

Merced County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (149 days to spare)
Transplant: Feb 13 🍅 Harvest: Apr 17 – Jun 26
Recommended (50%) ✓ Fits season (137 days to spare)
Transplant: Mar 3 🍅 Harvest: May 5 – Jul 14
Safe Start (90%) ✓ Fits season (102 days to spare)
Transplant: Apr 25 🍅 Harvest: Jun 27 – Sep 5

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.3″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 2,126 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Comfrey needs ~1,144 GDD — county provides 4,239 GDD Excellent fit

Comfrey Planting Timeline โ€” Merced County, CA

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors March 3 Mar 3 โ€“ Mar 17
Harvest May 5 May 5 โ€“ Jul 14

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Transplant Outdoors
April โ€”
May Harvest
June Harvest
July Harvest
August โ€”
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“90 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 9a

Growing Season

277 days

Growing Tips for Merced County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Comfrey in Merced County, CA?

Merced County is in Zone 9a with an average last frost of February 24. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Merced County, CA?

Merced County, California is in USDA Hardiness Zone 9a. The average last spring frost is February 24 and first fall frost is November 28.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Merced County gardeners in Zone 9a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Merced County, CA. Local conditions may vary. Last updated: April 2026.