Blog

When to Plant Horehound in Carter County, MT

Carter County, Montana Zone 4b May

May in the garden — Carter County, Montana

Each item below is timed to Carter County, Montana's frost dates and soil temperatures. Skip nothing, stress about nothing.

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. Move horehound from tray to bed

    Frost risk is low now in Carter County, Montana. If you've been covering beds overnight, you can stop.

Instant PDF download. No spam, unsubscribe any time.

Horehound is a woolly, drought-tolerant perennial herb traditionally used for cough remedies and candy. It has a distinctive bitter, menthol-like flavor.

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 Horehound to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Horehound 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

Carter County Soil Profile

Soil Type

Loam

Soil pH

6.4-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 18 🍅 Harvest: Aug 3 – Sep 28
Recommended (50%) ✗ May not fit
Transplant: May 22 🍅 Harvest: Aug 7 – Oct 2
Safe Start (90%) ✗ May not fit
Transplant: Jun 9 🍅 Harvest: Aug 25 – Oct 20

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 Horehound's growing requirements.

Soil pH

Your soil pH (6.4–8.2) overlaps with Horehound's range (6.0–8.0), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Horehound

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

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.6″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Horehound

Horehound needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Horehound 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 2.2" 2.4" 0" ✅ Rainfall sufficient
Jun 2.2" 1.4" 0.8" 💧 Light watering
Jul 2.2" 1.6" 0.6" 💧 Light watering
Aug 2.2" 1.9" 0.3" 💧 Light watering
Sep 2.2" 1.4" 0.8" 💧 Light 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.

Horehound 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.

Horehound needs ~887 GDD — county provides 1,397 GDD Excellent fit

Horehound Planting Timeline — Carter County, MT

Horehound Planting Calendar

Activity When Date Range
Transplant Outdoors May 22 May 22 – Jun 5
Harvest August 7 Aug 7 – Oct 2

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

75–90 days

🧪 Soil pH

Needs 6–8 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

130 days in Carter County

Growing Tips for Horehound in Carter County

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

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

General growing tips

Direct sow or start from divisions. Thrives in poor, dry soil. Harvest stems just before flowering. Deadhead to prevent aggressive self-seeding. Very drought-tolerant once established.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Horehound in Carter County, MT?

Carter County is in Zone 4b with an average last frost of May 15. Plan your Horehound 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.

Instant PDF download. No spam, unsubscribe any time.

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.