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When to Plant Comfrey in Brookings County, SD

Brookings County, South Dakota Zone 4b April

What to do in April

A quick April briefing for Brookings County, South Dakota gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 4
Avg. first frost October 2
Soil temp (4") 42°F
Watering Moderate
Pest pressure Low
Daylight 13.2 hrs
To set up a strong May, finish these tasks
  • Transplants going out: 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.

Brookings County, South Dakota is in USDA Zone 4b. The average last spring frost is May 4 and the first fall frost is October 2, giving you a growing season of approximately 151 days.

At an elevation of 901 feet, Brookings County receives approximately 32.4 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Comfrey to ensure they mature before fall.

Brookings County, SD (Zone 4b) Moderate season
151 days
Last Spring Frost May 4
151 growing days
First Fall Frost October 2
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Brookings County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (8 days to spare)
Transplant: May 5 🍅 Harvest: Jul 7 – Sep 15
Recommended (50%) ✓ Fits season (11 days to spare)
Transplant: May 11 🍅 Harvest: Jul 13 – Sep 21
Safe Start (90%) ✓ Fits season (11 days to spare)
Transplant: May 22 🍅 Harvest: Jul 24 – Oct 2

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 Brookings County

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

Soil pH

Your soil pH (6.6–7.7) is more alkaline than Comfrey prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.6%). Annual compost additions will help Comfrey.

How to Plant Comfrey

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

Succession Planting Comfrey

2
successive plantings in your 151-day season

Sow every 6.9 weeks. Last sowing by Jul 04 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 133 gal / 100 sq ft

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 0.8" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 3.7" 0" ❄️ Dormant
May 4.3" 5.1" 0" ✅ Rainfall sufficient
Jun 4.3" 4.6" 0" ✅ Rainfall sufficient
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 3.3" 1" 💧 Light watering
Sep 4.3" 3.3" 1" 💧 Light watering
Oct 4.3" 2.3" 2" 💧 Light watering
Nov 1" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Brookings 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 ~806 GDD — county provides 1,623 GDD Excellent fit

Comfrey Planting Timeline — Brookings County, SD

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 11 May 11 – May 25
Harvest July 13 Jul 13 – Sep 21

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

151 days in Brookings County

Growing Tips for Comfrey in Brookings County

Direct sow Comfrey outdoors after May 04 in Brookings County when soil has warmed and frost danger has passed.

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 Brookings County, SD?

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

What planting zone is Brookings County, SD?

Brookings County, South Dakota is in USDA Hardiness Zone 4b. The average last spring frost is May 4 and first fall frost is October 2.

🌱

Your Brookings County Garden Planner — Free

A 24-page printable planner built for Brookings 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 Brookings County, SD. Local conditions may vary. Last updated: April 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.