When to Plant Comfrey in Yellowstone County, MT
This month in Yellowstone County, Montana
Here's what deserves your attention in Yellowstone County, Montana this month. Everything below is tailored to Zone 5a and timed around your local frost dates.
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Harden off and plant comfrey
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.
Comfrey is a vigorous perennial herb valued as a dynamic accumulator of nutrients. Its leaves make excellent mulch, compost activator, and liquid fertilizer.
Yellowstone County, Montana is in USDA Zone 5a. The average last spring frost is May 9 and the first fall frost is October 3, giving you a growing season of approximately 147 days.
At an elevation of 7,432 feet, Yellowstone County receives approximately 21.1 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Comfrey to ensure they mature before fall.
Yellowstone County Soil Profile
Soil Type
Loam
Soil pH
6.2-8
Drainage
Well Drained
Plant Planting Risk Windows
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 Yellowstone County
How your county's soil matches Comfrey's growing requirements.
Soil pH
Your soil pH (6.2–8.0) is more alkaline than Comfrey prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Yellowstone 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 (2.4%). Annual compost additions will help Comfrey.
How to Plant Comfrey
Succession Planting Comfrey
Sow every 6.9 weeks. Last sowing by Jul 05 to harvest before frost.
Plant Water Budget
Water stress score is 8/10 — 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 | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 1.9" | 0" | ❄️ Dormant |
| Apr | — | 1.9" | 0" | ❄️ Dormant |
| May | 4.3" | 2.7" | 1.6" | 💧 Light watering |
| Jun | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Jul | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Aug | 4.3" | 2.5" | 1.8" | 💧 Light watering |
| Sep | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Oct | 4.3" | 1.8" | 2.5" | 🚿 Regular watering |
| Nov | — | 1.6" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Yellowstone 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 Planting Timeline — Yellowstone County, MT
Comfrey Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 16 | May 16 – May 30 |
| Harvest | July 18 | Jul 18 – Sep 26 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | — |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
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: too_alkaline
🗺️ USDA Zone
Zone 5a
📆 Growing Season
147 days in Yellowstone County
Growing Tips for Comfrey in Yellowstone County
Direct sow Comfrey outdoors after May 09 in Yellowstone County when soil has warmed and frost danger has passed.
Yellowstone County receives only 21" 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 →
Comfrey in Other Locations
Frequently Asked Questions
When should I plant Comfrey in Yellowstone County, MT?
Yellowstone County is in Zone 5a with an average last frost of May 9. Plan your Comfrey planting based on this frost date — see the calendar above for exact timing.
What planting zone is Yellowstone County, MT?
Yellowstone County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is May 9 and first fall frost is October 3.
Your Yellowstone County Garden Planner — Free
A 24-page printable planner built for Yellowstone County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.