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When to Plant Shiso in Adams County, OH

Adams County, Ohio Zone 6b May

Your May gardening checklist

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 22
Avg. first frost October 21
Soil temp (4") 64°F
Watering Low
Pest pressure Low
Daylight 14.1 hrs
  1. Move shiso into the garden

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

June prep starts now
  • Starting indoors: 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.

Adams County, Ohio is in USDA Zone 6b. The average last spring frost is April 22 and the first fall frost is October 21, giving you a growing season of approximately 182 days.

At an elevation of 1,217 feet, Adams County receives approximately 41.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Shiso during the growing season.

Adams County, OH (Zone 6b) Moderate season
182 days
Last Spring Frost April 22
182 growing days
First Fall Frost October 21
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Adams County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (61 days to spare)
Start indoors: Feb 23 Transplant: Apr 27 🍅 Harvest: Jun 22 – Aug 17
Recommended (50%) ✓ Fits season (56 days to spare)
Start indoors: Mar 4 Transplant: May 6 🍅 Harvest: Jul 1 – Aug 26
Safe Start (90%) ✓ Fits season (51 days to spare)
Start indoors: Mar 21 Transplant: May 23 🍅 Harvest: Jul 18 – Sep 12

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 Adams County

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

Soil pH

Your soil pH (5.9–6.8) is within Shiso's preferred range (5.5–7.0).

Soil Texture

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

Drainage

Drainage is adequate for Shiso.

Organic Matter

Organic matter is excellent (4.8%) — Shiso will thrive.

How to Plant Shiso

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

Succession Planting Shiso

4
successive plantings in your 182-day season

Sow every 5.7 weeks. Last sowing by Aug 12 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 683 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.6" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 4.3" 3.6" 0.7" 💧 Light watering
May 4.3" 5.5" 0" ✅ Rainfall sufficient
Jun 4.3" 5.5" 0" ✅ Rainfall sufficient
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 4.7" 0" ✅ Rainfall sufficient
Sep 4.3" 4.1" 0.2" 💧 Light watering
Oct 4.3" 2.9" 1.4" 💧 Light watering
Nov 2.5" 0" ❄️ Dormant
Dec 2.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Adams 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 ~1,005 GDD — county provides 3,048 GDD Excellent fit

Shiso Planting Timeline — Adams County, OH

Shiso Planting Calendar

Activity When Date Range
Start Indoors March 4 Mar 4 – Mar 18
Transplant Outdoors May 6 May 6 – May 20
Direct Sow April 29 Apr 29 – May 20
Harvest July 1 Jul 1 – Aug 26

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 5.5–7 · Your soil: ideal

🗺️ USDA Zone

Zone 6b

📆 Growing Season

182 days in Adams County

Growing Tips for Shiso in Adams County

Direct sow Shiso outdoors after April 22 in Adams 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 →

Frequently Asked Questions

When should I plant Shiso in Adams County, OH?

Adams County is in Zone 6b with an average last frost of April 22. Plan your Shiso planting based on this frost date — see the calendar above for exact timing.

What planting zone is Adams County, OH?

Adams County, Ohio is in USDA Hardiness Zone 6b. The average last spring frost is April 22 and first fall frost is October 21.

🌱

Your Adams County Garden Planner — Free

A 24-page printable planner built for Adams County (Zone 6b). 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 Adams County, OH. 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.