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When to Plant Mitsuba in St. Mary's County, MD

St. Mary's County, Maryland Zone 8a May

Your May planting checklist for St. Mary's County, Maryland

A quick May briefing for St. Mary's County, Maryland gardeners — what's urgent, what's next, and what can wait.

Avg. last frost April 5
Avg. first frost November 4
Soil temp (4") 68°F
Watering Low
Pest pressure Moderate
Daylight 14.1 hrs
  1. Sow mitsuba in trays indoors

    Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.

  2. It's harvest week for mitsuba

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

June prep starts now
  • 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.

St. Mary's County, Maryland is in USDA Zone 8a. The average last spring frost is April 5 and the first fall frost is November 4, giving you a growing season of approximately 213 days.

At an elevation of 156 feet, St. Mary's County receives approximately 41.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 92°F, providing good warmth for Mitsuba during the growing season.

St. Mary's County, MD (Zone 8a) Long season
213 days
Last Spring Frost April 5
213 growing days
First Fall Frost November 4

St. Mary's County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (111 days to spare)
Start indoors: Feb 21 Transplant: Mar 21 🍅 Harvest: May 16 – Jul 11
Recommended (50%) ✓ Fits season (108 days to spare)
Start indoors: Mar 1 Transplant: Mar 29 🍅 Harvest: May 24 – Jul 19
Safe Start (90%) ✓ Fits season (121 days to spare)
Start indoors: Mar 22 Transplant: Apr 19 🍅 Harvest: Jun 14 – Aug 9

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 St. Mary's County

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

Soil pH

Your soil pH (5.5–6.9) overlaps with Mitsuba's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.0%). 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

5
successive plantings in your 213-day season

Sow every 5.7 weeks. Last sowing by Aug 26 to harvest before frost.

For a dedicated fall crop, sow by Aug 26.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 344 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 3.1" 0" ❄️ Dormant
Feb 2.6" 0" ❄️ Dormant
Mar 3.3" 0" ❄️ Dormant
Apr 4.3" 3.3" 1" 💧 Light watering
May 4.3" 3.9" 0.4" 💧 Light watering
Jun 4.3" 4.3" 0" ✅ Rainfall sufficient
Jul 4.3" 4" 0.3" 💧 Light watering
Aug 4.3" 4.3" 0" ✅ Rainfall sufficient
Sep 4.3" 3.6" 0.7" 💧 Light watering
Oct 4.3" 3.4" 0.9" 💧 Light watering
Nov 4.3" 2.7" 1.6" 💧 Light watering
Dec 2.9" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Nov in St. Mary's 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 ~1,140 GDD — county provides 4,047 GDD Excellent fit

Mitsuba Planting Timeline — St. Mary's County, MD

Mitsuba Planting Calendar

Activity When Date Range
Start Indoors March 1 Mar 1 – Mar 15
Transplant Outdoors March 29 Mar 29 – Apr 12
Direct Sow March 22 Mar 22 – Apr 12
Harvest May 24 May 24 – Jul 19
Fall Sowing August 26 Aug 26 – Sep 9

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 8a

📆 Growing Season

213 days in St. Mary's County

Growing Tips for Mitsuba in St. Mary's County

Direct sow Mitsuba outdoors after April 05 in St. Mary's 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 St. Mary's County, MD?

St. Mary's County is in Zone 8a with an average last frost of April 5. Plan your Mitsuba planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Mary's County, MD?

St. Mary's County, Maryland is in USDA Hardiness Zone 8a. The average last spring frost is April 5 and first fall frost is November 4.

🌱

Your St. Mary's County Garden Planner — Free

A 24-page printable planner built for St. Mary's County (Zone 8a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for St. Mary's County, MD. 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.