When to Plant Lavender in Merrimack County, NH
May in Merrimack County, New Hampshire — your action list
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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Harden off and plant lavender
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.
Lavender is a fragrant perennial herb with silvery foliage and purple flower spikes. It is prized for its essential oils, culinary uses, and ornamental beauty.
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 Lavender 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 Lavender's growing requirements.
Soil pH
Your soil pH (4.9–6.7) is more acidic than Lavender prefers (6.5–8.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Merrimack County is excellent for Lavender — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.0%). Annual compost additions will help Lavender.
How to Plant Lavender
Plant Water Budget
Monthly Watering Guide for Lavender
Lavender needs approximately 0.3 inches of water per week (1.3" per month). Here's how your county's rainfall compares month by month.
| Month | Lavender 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 | 1.3" | 3.4" | 0" | ✅ Rainfall sufficient |
| Jun | 1.3" | 3.9" | 0" | ✅ Rainfall sufficient |
| Jul | 1.3" | 4.1" | 0" | ✅ Rainfall sufficient |
| Aug | 1.3" | 3.6" | 0" | ✅ Rainfall sufficient |
| Sep | 1.3" | 3.2" | 0" | ✅ Rainfall sufficient |
| Oct | 1.3" | 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.
Lavender 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.
Lavender Planting Timeline — Merrimack County, NH
Lavender Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 14 | May 14 – May 28 |
| Harvest | August 13 | Aug 13 – Oct 29 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | — |
| July | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.3"/week · Natural rainfall sufficient
📅 Days to Maturity
90–200 days
🧪 Soil pH
Needs 6.5–8 · Your soil: too_acidic
🗺️ USDA Zone
Zone 5b
📆 Growing Season
156 days in Merrimack County
Growing Tips for Lavender in Merrimack County
Direct sow Lavender outdoors after May 07 in Merrimack County when soil has warmed and frost danger has passed.
Your 156.0-day growing season in Merrimack County is tight for Lavender (90.0-200.0 days to maturity). Start indoors and choose early-maturing varieties.
General growing tips
Plant in well-drained, sandy soil. Avoid heavy mulching around the crown. Prune after flowering but do not cut into old wood. Lavender resents wet winter conditions.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Lavender in Other Locations
Frequently Asked Questions
When should I plant Lavender in Merrimack County, NH?
Merrimack County is in Zone 5b with an average last frost of May 7. Plan your Lavender 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.