When to Plant Mizuna in Merrimack County, NH
Your May planting checklist for Merrimack County, New Hampshire
We've pulled the most time-sensitive tasks for Merrimack County, New Hampshire this May and put them front and centre. Tackle them in order.
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Harden off and plant mizuna
Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.
Before June arrives, get these ready
- Starting indoors: mizuna
- First harvests: mizuna
Mizuna is a mild-flavored Japanese mustard green with feathery, deeply serrated leaves. It is fast-growing and makes an excellent addition to salads and stir-fries.
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 Mizuna 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 Mizuna's growing requirements.
Soil pH
Your soil pH (4.9–6.7) is more acidic than Mizuna prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Merrimack County is excellent for Mizuna — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.0%). Annual compost additions will help Mizuna.
How to Plant Mizuna
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Mizuna
Sow every 3.4 weeks. Last sowing by Aug 26 to harvest before frost.
For a dedicated fall crop, sow by Aug 01.
Plant Water Budget
Monthly Watering Guide for Mizuna
Mizuna needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Mizuna 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 | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Jun | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Jul | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Aug | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Sep | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| Oct | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| 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.
Mizuna 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.
Mizuna Planting Timeline — Merrimack County, NH
Mizuna Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 2 | Apr 2 – Apr 16 |
| Transplant Outdoors | May 7 | May 7 – May 21 |
| Direct Sow | April 23 | Apr 23 – May 14 |
| Harvest | June 11 | Jun 11 – Jul 9 |
| Fall Sowing | August 1 | Aug 1 – Aug 15 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Fall Sowing |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1"/week · Natural rainfall sufficient
📅 Days to Maturity
30–45 days
🧪 Soil pH
Needs 6–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 5b
📆 Growing Season
156 days in Merrimack County
Growing Tips for Mizuna in Merrimack County
Direct sow Mizuna outdoors after May 07 in Merrimack County when soil has warmed and frost danger has passed.
Your generous 156.0-day season in Merrimack County allows multiple plantings of Mizuna. Sow every 15.0 days for continuous harvest.
Common pests for Mizuna in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow in spring or fall. Harvest outer leaves as needed for a cut-and-come-again approach. Mizuna is one of the most cold-tolerant Asian greens.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Mizuna in Other Locations
Frequently Asked Questions
When should I plant Mizuna in Merrimack County, NH?
Merrimack County is in Zone 5b with an average last frost of May 7. Plan your Mizuna 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.