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When to Plant Shiso in Carroll County, KY

Carroll County, Kentucky Zone 6b May

What to do in May

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Carroll County, Kentucky.

Avg. last frost April 18
Avg. first frost October 20
Soil temp (4") 57°F
Watering Moderate
Pest pressure Low
Daylight 14.1 hrs
  1. Get shiso in the ground

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

A few tasks this May that'll pay off in June
  • Starting indoors: shiso
  • 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.

Carroll County, Kentucky is in USDA Zone 6b. The average last spring frost is April 18 and the first fall frost is October 20, giving you a growing season of approximately 185 days.

At an elevation of 3,005 feet, Carroll County receives approximately 42.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Shiso during the growing season.

Carroll County, KY (Zone 6b) Moderate season
185 days
Last Spring Frost April 18
185 growing days
First Fall Frost October 20
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Carroll County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (62 days to spare)
Start indoors: Feb 20 Transplant: Apr 24 🍅 Harvest: Jun 19 – Aug 14
Recommended (50%) ✓ Fits season (59 days to spare)
Start indoors: Feb 28 Transplant: May 2 🍅 Harvest: Jun 27 – Aug 22
Safe Start (90%) ✓ Fits season (50 days to spare)
Start indoors: Mar 20 Transplant: May 22 🍅 Harvest: Jul 17 – Sep 11

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 Carroll County

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

Soil pH

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

Soil Texture

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

Organic Matter

Organic matter is moderate (3.0%). Annual compost additions will help Shiso.

How to Plant Shiso

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

Succession Planting Shiso

4
successive plantings in your 185-day season

Sow every 5.7 weeks. Last sowing by Aug 11 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 62 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 3.7" 0" ❄️ Dormant
Feb 3.6" 0" ❄️ Dormant
Mar 3.7" 0" ❄️ Dormant
Apr 4.3" 2.8" 1.5" 💧 Light watering
May 4.3" 3.5" 0.8" 💧 Light watering
Jun 4.3" 4.3" 0" ✅ Rainfall sufficient
Jul 4.3" 4.2" 0.1" 💧 Light watering
Aug 4.3" 4.5" 0" ✅ Rainfall sufficient
Sep 4.3" 3" 1.3" 💧 Light watering
Oct 4.3" 3" 1.3" 💧 Light watering
Nov 2.8" 0" ❄️ Dormant
Dec 3.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Carroll 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 ~1,050 GDD — county provides 3,237 GDD Excellent fit

Shiso Planting Timeline — Carroll County, KY

Shiso Planting Calendar

Activity When Date Range
Start Indoors February 28 Feb 28 – Mar 14
Transplant Outdoors May 2 May 2 – May 16
Direct Sow April 25 Apr 25 – May 16
Harvest June 27 Jun 27 – Aug 22

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 5.5–7 · Your soil: ideal

🗺️ USDA Zone

Zone 6b

📆 Growing Season

185 days in Carroll County

Growing Tips for Shiso in Carroll County

Direct sow Shiso outdoors after April 18 in Carroll 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 Carroll County, KY?

Carroll County is in Zone 6b with an average last frost of April 18. Plan your Shiso planting based on this frost date — see the calendar above for exact timing.

What planting zone is Carroll County, KY?

Carroll County, Kentucky is in USDA Hardiness Zone 6b. The average last spring frost is April 18 and first fall frost is October 20.

🌱

Your Carroll County Garden Planner — Free

A 24-page printable planner built for Carroll 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 Carroll County, KY. 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.