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When to plant Shiso in Danforth, ME

Plant Shiso in Danforth from May 16 to June 6 in spring. Danforth sits in USDA Zone 5b, with last frost around May 9 and first frost on October 7.

When to Plant Shiso in Danforth, ME

Washington County, Maine Zone 5b August

Your August planting checklist for Washington County, Maine

August is a pivotal month for Washington County, Maine gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 9
Avg. first frost October 7
Soil temp (4") 73°F
Watering Low
Pest pressure High
Daylight 13.9 hrs
  1. Start harvesting shiso

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

A few tasks this August that'll pay off in September
  • First harvests: shiso

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Shiso (perilla) is a fragrant Japanese herb with large, ruffled leaves in green or purple varieties. It has a unique flavor combining mint, basil, and anise.

Danforth, Maine is in USDA Zone 5b. The average last spring frost is May 9 and the first fall frost is October 7, giving you a growing season of approximately 151 days.

At an elevation of 1,184 feet, Washington County receives approximately 43.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Shiso to ensure they mature before fall.

Danforth, ME (Zone 5b) Moderate season
151 days
Last Spring Frost May 9
151 growing days
First Fall Frost October 7

Danforth Soil Profile

Soil Type

Silt Loam

Soil pH

5-6.5

Drainage

Well Drained

Shiso Planting Risk Windows

Early Start (70% safe) ✓ Fits season (30 days to spare)
Start indoors: Mar 13 Transplant: May 15 🍅 Harvest: Jul 10 – Sep 4
Recommended (50%) ✓ Fits season (25 days to spare)
Start indoors: Mar 21 Transplant: May 23 🍅 Harvest: Jul 18 – Sep 12
Safe Start (90%) ✓ Fits season (32 days to spare)
Start indoors: Apr 8 Transplant: Jun 10 🍅 Harvest: Aug 5 – Sep 30

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 Danforth

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

Soil pH

Your soil pH (5.0–6.5) overlaps with Shiso's range (5.5–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.7%). Annual compost additions will help Shiso.

How to Plant Shiso

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

Succession Planting Shiso

3
successive plantings in your 151-day season

Sow every 5.7 weeks. Last sowing by Jul 29 to harvest before frost.

Shiso Water Budget

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

Monthly Watering Guide for Shiso

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

Month Shiso Needs Rainfall You Supplement Action
Jan 3.2" 0" ❄️ Dormant
Feb 3" 0" ❄️ Dormant
Mar 4.1" 0" ❄️ Dormant
Apr 3.5" 0" ❄️ Dormant
May 4.3" 3.5" 0.8" 💧 Light watering
Jun 4.3" 4.7" 0" ✅ Rainfall sufficient
Jul 4.3" 4.1" 0.2" 💧 Light watering
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 3.8" 0.5" 💧 Light watering
Oct 4.3" 3.4" 0.9" 💧 Light watering
Nov 3.4" 0" ❄️ Dormant
Dec 3.2" 0" ❄️ Dormant

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

Shiso 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.

Shiso needs ~600 GDD — county provides 1,510 GDD Excellent fit

Shiso Planting Timeline — Danforth, ME

Shiso Planting Calendar

Activity When Date Range
Start Indoors March 21 Mar 21 – Apr 4
Transplant Outdoors May 23 May 23 – Jun 6
Direct Sow May 16 May 16 – Jun 6
Harvest July 18 Jul 18 – Sep 12

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 5.5–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

151 days in Washington County

Growing Tips for Shiso in Danforth

Direct sow Shiso outdoors after May 09 in Washington County when soil has warmed and frost danger has passed.

General growing tips

Direct sow after last frost or start indoors. Both green and red varieties are available. Pinch tips to encourage bushiness. Self-sows prolifically; deadhead to control.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

When should I plant Shiso in Danforth, ME?

In Danforth, ME, plant Shiso after the last frost (around May 9) and before the first frost (around October 7). Best results when soil holds above 50°F.

What growing zone is Danforth, ME for Shiso?

Danforth sits in USDA Zone 5b. Shiso grows reliably in zones 3a through 11b, so it's a good fit here.

Can Shiso grow in Danforth's climate?

Yes — Shiso grows well in Danforth's temperate climate. Danforth averages a 151-day frost-free season, with last frost around May 9 and first frost around October 7.

🌱

Your Washington County Garden Planner — Free

A 22-page printable planner built for Washington 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.

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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 Washington County, ME. Local conditions may vary. Last updated: August 2026.