When to Plant Horehound in Merrimack County, NH
May to-do list for Merrimack County, New Hampshire
Here's what deserves your attention in Merrimack County, New Hampshire this month. Everything below is tailored to Zone 5b and timed around your local frost dates.
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Move horehound from tray to bed
Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.
Horehound is a woolly, drought-tolerant perennial herb traditionally used for cough remedies and candy. It has a distinctive bitter, menthol-like flavor.
Merrimack County, New Hampshire is in USDA Zone 5b. The average last spring frost is May 7 and the first fall frost is October 10, giving you a growing season of approximately 156 days.
At an elevation of 836 feet, Merrimack County receives approximately 40.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Horehound during the growing season.
Merrimack County Soil Profile
Soil Type
Silt Loam
Soil pH
4.9-6.7
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 Merrimack County
How your county's soil matches Horehound's growing requirements.
Soil pH
Your soil pH (4.9–6.7) is more acidic than Horehound prefers (6.0–8.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Merrimack County is excellent for Horehound — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.0%). Annual compost additions will help Horehound.
How to Plant Horehound
Succession Planting Horehound
Sow every 8.6 weeks. Last sowing by Jul 12 to harvest before frost.
Plant Water Budget
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 | — | 2.9" | 0" | ❄️ Dormant |
| Feb | — | 3.1" | 0" | ❄️ Dormant |
| Mar | — | 3.9" | 0" | ❄️ Dormant |
| Apr | — | 3.2" | 0" | ❄️ Dormant |
| May | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 3.9" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 4.1" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.2" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 3.2" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.7" | 0" | ❄️ Dormant |
| Dec | — | 3.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Merrimack 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 Planting Timeline — Merrimack County, NH
Horehound Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 14 | May 14 – May 28 |
| Harvest | July 30 | Jul 30 – Sep 24 |
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
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: too_acidic
🗺️ USDA Zone
Zone 5b
📆 Growing Season
156 days in Merrimack County
Growing Tips for Horehound in Merrimack County
Direct sow Horehound outdoors after May 07 in Merrimack County when soil has warmed and frost danger has passed.
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 →
Horehound in Other Locations
Frequently Asked Questions
When should I plant Horehound in Merrimack County, NH?
Merrimack County is in Zone 5b with an average last frost of May 7. Plan your Horehound planting based on this frost date — see the calendar above for exact timing.
What planting zone is Merrimack County, NH?
Merrimack County, New Hampshire is in USDA Hardiness Zone 5b. The average last spring frost is May 7 and first fall frost is October 10.
Your Merrimack County Garden Planner — Free
A 24-page printable planner built for Merrimack County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.