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When to Plant Shiso in Jefferson County, NE

Jefferson County, Nebraska Zone 6a May

Your May game plan for Jefferson County, Nebraska

Here's what deserves your attention in Jefferson County, Nebraska this month. Everything below is tailored to Zone 6a and timed around your local frost dates.

Avg. last frost April 22
Avg. first frost October 13
Soil temp (4") 59°F
Watering Moderate
Pest pressure Low
Daylight 14.2 hrs
  1. Time to transplant shiso

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

Before June arrives, get these ready
  • 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.

Jefferson County, Nebraska is in USDA Zone 6a. The average last spring frost is April 22 and the first fall frost is October 13, giving you a growing season of approximately 174 days.

At an elevation of 727 feet, Jefferson County receives approximately 22 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Shiso to ensure they mature before fall.

Jefferson County, NE (Zone 6a) Moderate season
174 days
Last Spring Frost April 22
174 growing days
First Fall Frost October 13

Jefferson County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (51 days to spare)
Start indoors: Feb 26 Transplant: Apr 30 🍅 Harvest: Jun 25 – Aug 20
Recommended (50%) ✓ Fits season (48 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 15 Transplant: May 17 🍅 Harvest: Jul 12 – Sep 6

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 Jefferson County

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

Soil pH

Your soil pH (6.4–7.7) is more alkaline than Shiso prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.0%) — 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 174-day season

Sow every 5.7 weeks. Last sowing by Aug 04 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 871 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 0.5" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 4.3" 2.3" 2" 💧 Light watering
May 4.3" 3.3" 1" 💧 Light watering
Jun 4.3" 3.1" 1.2" 💧 Light watering
Jul 4.3" 2.6" 1.7" 💧 Light watering
Aug 4.3" 3" 1.3" 💧 Light watering
Sep 4.3" 2.2" 2.1" 💧 Light watering
Oct 4.3" 1.4" 2.9" 🚿 Regular watering
Nov 0.7" 0" ❄️ Dormant
Dec 0.6" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Jefferson 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 ~780 GDD — county provides 2,262 GDD Excellent fit

Shiso Planting Timeline — Jefferson County, NE

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

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: too_alkaline

🗺️ USDA Zone

Zone 6a

📆 Growing Season

174 days in Jefferson County

Growing Tips for Shiso in Jefferson County

Direct sow Shiso outdoors after April 22 in Jefferson County when soil has warmed and frost danger has passed.

Jefferson County receives only 22" of rain annually. Shiso needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Jefferson County, NE?

Jefferson County is in Zone 6a 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 Jefferson County, NE?

Jefferson County, Nebraska is in USDA Hardiness Zone 6a. The average last spring frost is April 22 and first fall frost is October 13.

🌱

Your Jefferson County Garden Planner — Free

A 24-page printable planner built for Jefferson County (Zone 6a). 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 Jefferson County, NE. 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.