Blog

When to Plant Shiso in Wharton County, TX

Wharton County, Texas Zone 9a May

Your May game plan for Wharton County, Texas

Each item below is timed to Wharton County, Texas's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost February 17
Avg. first frost December 6
Soil temp (4") 76°F
Watering Low
Pest pressure High
Daylight 13.5 hrs
  1. Start harvesting shiso

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

To set up a strong June, finish these tasks
  • First harvests: shiso

Instant PDF download. No spam, unsubscribe any time.

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.

Wharton County, Texas is in USDA Zone 9a. The average last spring frost is February 17 and the first fall frost is December 6, giving you a growing season of approximately 292 days.

At an elevation of 207 feet, Wharton County receives approximately 64.8 inches of rainfall annually with predominantly loam soil. Summer highs average 98°F, so Shiso may need afternoon shade and extra watering during peak heat. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Shiso root diseases.

Wharton County, TX (Zone 9a) Year-round
292 days
Last Spring Frost February 17
292 growing days
First Fall Frost December 6

Wharton County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (176 days to spare)
Start indoors: Dec 25 Transplant: Feb 12 🍅 Harvest: Apr 9 – Jun 4
Recommended (50%) ✓ Fits season (173 days to spare)
Start indoors: Jan 6 Transplant: Feb 24 🍅 Harvest: Apr 21 – Jun 16
Safe Start (90%) ✓ Fits season (165 days to spare)
Start indoors: Jan 29 Transplant: Mar 19 🍅 Harvest: May 14 – Jul 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 Wharton County

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

Soil pH

Your soil pH (6.6–7.7) is more alkaline than Shiso prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Shiso.

How to Plant Shiso

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

Succession Planting Shiso

7
successive plantings in your 292-day season

Sow every 5.7 weeks. Last sowing by Sep 27 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 185 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 1.7" 0" ❄️ Dormant
Feb 4.3" 2.2" 2.1" 💧 Light watering
Mar 4.3" 4.6" 0" ✅ Rainfall sufficient
Apr 4.3" 6.6" 0" ✅ Rainfall sufficient
May 4.3" 9" 0" ✅ Rainfall sufficient
Jun 4.3" 10.4" 0" ✅ Rainfall sufficient
Jul 4.3" 8.4" 0" ✅ Rainfall sufficient
Aug 4.3" 7.4" 0" ✅ Rainfall sufficient
Sep 4.3" 5.7" 0" ✅ Rainfall sufficient
Oct 4.3" 4.4" 0" ✅ Rainfall sufficient
Nov 4.3" 2.4" 1.9" 💧 Light watering
Dec 4.3" 1.9" 2.4" 🚿 Regular watering

Water needs are for active growing months only (Feb–Dec in Wharton 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 ~1,410 GDD — county provides 6,885 GDD Excellent fit

Shiso Planting Timeline — Wharton County, TX

Shiso Planting Calendar

Activity When Date Range
Start Indoors January 6 Jan 6 – Jan 20
Transplant Outdoors February 24 Feb 24 – Mar 10
Direct Sow February 24 Feb 24 – Mar 17
Harvest April 21 Apr 21 – Jun 16

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

Month-by-Month Timeline

MonthActivities
January Start Indoors
February Transplant Outdoors Direct Sow
March Transplant Outdoors Direct Sow
April Harvest
May Harvest
June Harvest
July
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: too_alkaline

🗺️ USDA Zone

Zone 9a

📆 Growing Season

292 days in Wharton County

Growing Tips for Shiso in Wharton County

Direct sow Shiso outdoors after February 17 in Wharton County when soil has warmed and frost danger has passed.

With summer highs reaching 98°F in Wharton County, provide afternoon shade for Shiso and water deeply in the morning.

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 Wharton County, TX?

Wharton County is in Zone 9a with an average last frost of February 17. Plan your Shiso planting based on this frost date — see the calendar above for exact timing.

What planting zone is Wharton County, TX?

Wharton County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 17 and first fall frost is December 6.

🌱

Your Wharton County Garden Planner — Free

A 24-page printable planner built for Wharton County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

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