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When to Plant Shiso in Minidoka County, ID

Minidoka County, Idaho Zone 6a May

This month in Minidoka County, Idaho

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

Avg. last frost May 10
Avg. first frost October 3
Soil temp (4") 40°F
Watering High
Pest pressure Low
Daylight 14.4 hrs
  1. Move shiso into the garden

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Put shiso seeds straight in the ground

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

Get ahead of June
  • 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.

Minidoka County, Idaho is in USDA Zone 6a. The average last spring frost is May 10 and the first fall frost is October 3, giving you a growing season of approximately 146 days.

At an elevation of 5,990 feet, Minidoka County receives approximately 22.3 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Shiso during the growing season.

Minidoka County, ID (Zone 6a) Short season
146 days
Last Spring Frost May 10
146 growing days
First Fall Frost October 3

Minidoka County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (22 days to spare)
Start indoors: Mar 13 Transplant: May 15 🍅 Harvest: Jul 10 – Sep 4
Recommended (50%) ✓ Fits season (20 days to spare)
Start indoors: Mar 22 Transplant: May 24 🍅 Harvest: Jul 19 – Sep 13
Safe Start (90%) ✓ Fits season (12 days to spare)
Start indoors: Apr 18 Transplant: Jun 20 🍅 Harvest: Aug 15 – Oct 10

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 Minidoka County

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

Soil pH

Your soil pH (6.6–7.8) is more alkaline than Shiso prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Shiso.

How to Plant Shiso

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

Succession Planting Shiso

3
successive plantings in your 146-day season

Sow every 5.7 weeks. Last sowing by Jul 25 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 559 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 1.7" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2.5" 0" ❄️ Dormant
May 4.3" 2.5" 1.8" 💧 Light watering
Jun 4.3" 1.4" 2.9" 🚿 Regular watering
Jul 4.3" 2" 2.3" 🚿 Regular watering
Aug 4.3" 2.5" 1.8" 💧 Light watering
Sep 4.3" 2.1" 2.2" 🚿 Regular watering
Oct 4.3" 1.7" 2.6" 🚿 Regular watering
Nov 1.5" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Minidoka 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 ~870 GDD — county provides 2,117 GDD Excellent fit

Shiso Planting Timeline — Minidoka County, ID

Shiso Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 – Apr 5
Transplant Outdoors May 24 May 24 – Jun 7
Direct Sow May 17 May 17 – Jun 7
Harvest July 19 Jul 19 – Sep 13

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July Harvest
August Harvest
September Harvest
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

146 days in Minidoka County

Growing Tips for Shiso in Minidoka County

Direct sow Shiso outdoors after May 10 in Minidoka County when soil has warmed and frost danger has passed.

Minidoka 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 Minidoka County, ID?

Minidoka County is in Zone 6a with an average last frost of May 10. Plan your Shiso planting based on this frost date — see the calendar above for exact timing.

What planting zone is Minidoka County, ID?

Minidoka County, Idaho is in USDA Hardiness Zone 6a. The average last spring frost is May 10 and first fall frost is October 3.

🌱

Your Minidoka County Garden Planner — Free

A 24-page printable planner built for Minidoka 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 Minidoka County, ID. 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.