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When to Plant Mitsuba in Bristol County, RI

Bristol County, Rhode Island Zone 7a May

Your May game plan for Bristol County, Rhode Island

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost April 26
Avg. first frost October 17
Soil temp (4") 62°F
Watering Moderate
Pest pressure Low
Daylight 14.4 hrs
  1. Fire up the seed-starting tray: mitsuba

    A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.

Looking ahead to June
  • First harvests: mitsuba

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Mitsuba (Japanese parsley) is a shade-loving herb with trefoil leaves and a mild celery-parsley flavor. It is essential in Japanese cuisine for soups, salads, and garnishes.

Bristol County, Rhode Island is in USDA Zone 7a. The average last spring frost is April 26 and the first fall frost is October 17, giving you a growing season of approximately 174 days.

At an elevation of 335 feet, Bristol County receives approximately 41.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Mitsuba during the growing season.

Bristol County, RI (Zone 7a) Moderate season
174 days
Last Spring Frost April 26
174 growing days
First Fall Frost October 17
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Bristol County Soil Profile

Soil Type

Silt Loam

Soil pH

4.8-6.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (70 days to spare)
Start indoors: Mar 15 Transplant: Apr 12 🍅 Harvest: Jun 7 – Aug 2
Recommended (50%) ✓ Fits season (69 days to spare)
Start indoors: Mar 22 Transplant: Apr 19 🍅 Harvest: Jun 14 – Aug 9
Safe Start (90%) ✓ Fits season (66 days to spare)
Start indoors: Apr 9 Transplant: May 7 🍅 Harvest: Jul 2 – Aug 27

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 Bristol County

How your county's soil matches Mitsuba's growing requirements.

Soil pH

Your soil pH (4.8–6.2) is more acidic than Mitsuba prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Bristol County is excellent for Mitsuba — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (4.0%). Annual compost additions will help Mitsuba.

How to Plant Mitsuba

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Mitsuba

4
successive plantings in your 174-day season

Sow every 5.7 weeks. Last sowing by Aug 08 to harvest before frost.

For a dedicated fall crop, sow by Aug 08.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Mitsuba

Mitsuba needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Mitsuba Needs Rainfall You Supplement Action
Jan 2.8" 0" ❄️ Dormant
Feb 3.1" 0" ❄️ Dormant
Mar 3.6" 0" ❄️ Dormant
Apr 4.3" 3.6" 0.7" 💧 Light watering
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 4.2" 0.1" 💧 Light watering
Jul 4.3" 4.5" 0" ✅ Rainfall sufficient
Aug 4.3" 3.8" 0.5" 💧 Light watering
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 4.3" 3.1" 1.2" 💧 Light watering
Nov 3.5" 0" ❄️ Dormant
Dec 3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Bristol County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Mitsuba 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.

Mitsuba needs ~915 GDD — county provides 2,653 GDD Excellent fit

Mitsuba Planting Timeline — Bristol County, RI

Mitsuba Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 – Apr 5
Transplant Outdoors April 19 Apr 19 – May 3
Direct Sow April 12 Apr 12 – May 3
Harvest June 14 Jun 14 – Aug 9
Fall Sowing August 8 Aug 8 – Aug 22

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Harvest
August Fall Sowing Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 7a

📆 Growing Season

174 days in Bristol County

Growing Tips for Mitsuba in Bristol County

Direct sow Mitsuba outdoors after April 26 in Bristol County when soil has warmed and frost danger has passed.

Common pests for Mitsuba in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow or start indoors in partial shade. Mitsuba prefers cool, moist conditions. Harvest outer stems as needed. Self-sows readily in shaded garden areas.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mitsuba in Bristol County, RI?

Bristol County is in Zone 7a with an average last frost of April 26. Plan your Mitsuba planting based on this frost date — see the calendar above for exact timing.

What planting zone is Bristol County, RI?

Bristol County, Rhode Island is in USDA Hardiness Zone 7a. The average last spring frost is April 26 and first fall frost is October 17.

🌱

Your Bristol County Garden Planner — Free

A 24-page printable planner built for Bristol County (Zone 7a). 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 Bristol County, RI. 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.