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When to Plant Shiso in Middlesex County, NJ

Middlesex County, New Jersey Zone 7a May

May to-do list for Middlesex County, New Jersey

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 March 29
Avg. first frost November 12
Soil temp (4") 69°F
Watering Low
Pest pressure Moderate
Daylight 14.2 hrs
  1. Indoor seed-starting week for shiso

    Starting these indoors now means sturdy transplants ready the moment your soil warms up.

To set up a strong June, finish these tasks
  • 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.

Middlesex County, New Jersey is in USDA Zone 7a. The average last spring frost is March 29 and the first fall frost is November 12, giving you a growing season of approximately 228 days.

At an elevation of 947 feet, Middlesex County receives approximately 45.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 94°F, providing good warmth for Shiso during the growing season.

Middlesex County, NJ (Zone 7a) Long season
228 days
Last Spring Frost March 29
228 growing days
First Fall Frost November 12
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Middlesex County Soil Profile

Soil Type

Silt Loam

Soil pH

5-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (102 days to spare)
Start indoors: Feb 4 Transplant: Apr 8 🍅 Harvest: Jun 3 – Jul 29
Recommended (50%) ✓ Fits season (102 days to spare)
Start indoors: Feb 8 Transplant: Apr 12 🍅 Harvest: Jun 7 – Aug 2
Safe Start (90%) ✓ Fits season (111 days to spare)
Start indoors: Feb 19 Transplant: Apr 23 🍅 Harvest: Jun 18 – Aug 13

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 Middlesex County

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

Soil pH

Your soil pH (5.0–6.6) overlaps with Shiso's range (5.5–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.4%). Annual compost additions will help Shiso.

How to Plant Shiso

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

Succession Planting Shiso

5
successive plantings in your 228-day season

Sow every 5.7 weeks. Last sowing by Sep 03 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 328 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 3.3" 0" ❄️ Dormant
Feb 3.1" 0" ❄️ Dormant
Mar 4.3" 3.6" 0.7" 💧 Light watering
Apr 4.3" 4.2" 0.1" 💧 Light watering
May 4.3" 4.8" 0" ✅ Rainfall sufficient
Jun 4.3" 4.9" 0" ✅ Rainfall sufficient
Jul 4.3" 4" 0.3" 💧 Light watering
Aug 4.3" 4.3" 0" ✅ Rainfall sufficient
Sep 4.3" 3.4" 0.9" 💧 Light watering
Oct 4.3" 3.7" 0.6" 💧 Light watering
Nov 4.3" 3.2" 1.1" 💧 Light watering
Dec 3" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Middlesex 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 ~1,230 GDD — county provides 4,674 GDD Excellent fit

Shiso Planting Timeline — Middlesex County, NJ

Shiso Planting Calendar

Activity When Date Range
Start Indoors February 8 Feb 8 – Feb 22
Transplant Outdoors April 12 Apr 12 – Apr 26
Direct Sow April 5 Apr 5 – Apr 26
Harvest June 7 Jun 7 – Aug 2

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

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March
April Transplant Outdoors Direct Sow
May
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: acceptable

🗺️ USDA Zone

Zone 7a

📆 Growing Season

228 days in Middlesex County

Growing Tips for Shiso in Middlesex County

Direct sow Shiso outdoors after March 29 in Middlesex 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 Middlesex County, NJ?

Middlesex County is in Zone 7a with an average last frost of March 29. Plan your Shiso planting based on this frost date — see the calendar above for exact timing.

What planting zone is Middlesex County, NJ?

Middlesex County, New Jersey is in USDA Hardiness Zone 7a. The average last spring frost is March 29 and first fall frost is November 12.

🌱

Your Middlesex County Garden Planner — Free

A 24-page printable planner built for Middlesex County (Zone 7a). 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 Middlesex County, NJ. 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.