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When to Plant Shiso in Humphreys County, MS

Humphreys County, Mississippi Zone 8b May

May in the garden — Humphreys County, Mississippi

We've pulled the most time-sensitive tasks for Humphreys County, Mississippi this May and put them front and centre. Tackle them in order.

Avg. last frost March 6
Avg. first frost November 18
Soil temp (4") 73°F
Watering Low
Pest pressure High
Daylight 13.7 hrs
  1. Collect shiso at their peak

    If you can't use it all right away, check the food-preservation section of your planner.

June prep starts now
  • 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.

Humphreys County, Mississippi is in USDA Zone 8b. The average last spring frost is March 6 and the first fall frost is November 18, giving you a growing season of approximately 257 days.

At an elevation of 303 feet, Humphreys County receives approximately 57.8 inches of rainfall annually with predominantly clay loam soil. Summer highs average 93°F, providing good warmth for Shiso during the growing season. Clay soil retains moisture well for Shiso, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Shiso root diseases.

Humphreys County, MS (Zone 8b) Long season
257 days
Last Spring Frost March 6
257 growing days
First Fall Frost November 18

Humphreys County Soil Profile

Soil Type

Clay Loam

Soil pH

5.5-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (127 days to spare)
Start indoors: Jan 11 Transplant: Mar 15 🍅 Harvest: May 10 – Jul 5
Recommended (50%) ✓ Fits season (131 days to spare)
Start indoors: Jan 16 Transplant: Mar 20 🍅 Harvest: May 15 – Jul 10
Safe Start (90%) ✓ Fits season (124 days to spare)
Start indoors: Feb 4 Transplant: Apr 8 🍅 Harvest: Jun 3 – Jul 29

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 Humphreys County

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

Soil pH

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

Soil Texture

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

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Shiso.

How to Plant Shiso

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

Succession Planting Shiso

6
successive plantings in your 257-day season

Sow every 5.7 weeks. Last sowing by Sep 09 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 127 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 4.9" 0" ❄️ Dormant
Feb 4.5" 0" ❄️ Dormant
Mar 4.3" 5.6" 0" ✅ Rainfall sufficient
Apr 4.3" 4.1" 0.2" 💧 Light watering
May 4.3" 4.8" 0" ✅ Rainfall sufficient
Jun 4.3" 4.8" 0" ✅ Rainfall sufficient
Jul 4.3" 6.4" 0" ✅ Rainfall sufficient
Aug 4.3" 5.9" 0" ✅ Rainfall sufficient
Sep 4.3" 4.1" 0.2" 💧 Light watering
Oct 4.3" 3.8" 0.5" 💧 Light watering
Nov 4.3" 4.5" 0" ✅ Rainfall sufficient
Dec 4.4" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Humphreys 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 ~1,185 GDD — county provides 5,075 GDD Excellent fit

Shiso Planting Timeline — Humphreys County, MS

Shiso Planting Calendar

Activity When Date Range
Start Indoors January 16 Jan 16 – Jan 30
Transplant Outdoors March 20 Mar 20 – Apr 3
Direct Sow March 13 Mar 13 – Apr 3
Harvest May 15 May 15 – Jul 10

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

Month-by-Month Timeline

MonthActivities
January Start Indoors
February
March Transplant Outdoors Direct Sow
April Transplant Outdoors Direct Sow
May Harvest
June Harvest
July Harvest
August
September
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 5.5–7 · Your soil: ideal

🗺️ USDA Zone

Zone 8b

📆 Growing Season

257 days in Humphreys County

Growing Tips for Shiso in Humphreys County

Direct sow Shiso outdoors after March 06 in Humphreys County when soil has warmed and frost danger has passed.

With Humphreys County's clay soil (29% clay), work in 3-4 inches of compost before planting Shiso. Avoid tilling when soil is wet to prevent compaction.

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 Humphreys County, MS?

Humphreys County is in Zone 8b with an average last frost of March 6. Plan your Shiso planting based on this frost date — see the calendar above for exact timing.

What planting zone is Humphreys County, MS?

Humphreys County, Mississippi is in USDA Hardiness Zone 8b. The average last spring frost is March 6 and first fall frost is November 18.

🌱

Your Humphreys County Garden Planner — Free

A 24-page printable planner built for Humphreys County (Zone 8b). 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 Humphreys County, MS. 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.