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When to plant Shiso in Otter Tail County, MN

Otter Tail County sits in cold Zone 4a. Plant Shiso May 18–June 8 for the single annual harvest; the September 28 first frost closes the window.

When to Plant Shiso in Otter Tail County, MN

Otter Tail County, Minnesota Zone 4a June

Otter Tail County, Minnesota gardeners: here's your June plan

Your garden in Otter Tail County, Minnesota is working on a schedule, even when you're not. Here's where you should be this June.

Avg. last frost May 11
Avg. first frost September 28
Soil temp (4") 63°F
Watering Low
Pest pressure Moderate
Daylight 15.6 hrs
  1. Move shiso from tray to bed

    Your last frost (May 11) has passed. These warm-season crops can handle outdoor soil now.

Looking ahead to July
  • Starting indoors: shiso
  • 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.

Otter Tail County, Minnesota is in USDA Zone 4a. The average last spring frost is May 11 and the first fall frost is September 28, giving you a growing season of approximately 140 days.

At an elevation of 571 feet, Otter Tail County receives approximately 40.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Shiso to ensure they mature before fall.

Otter Tail County, MN (Zone 4a) Short season
140 days
Last Spring Frost May 11
140 growing days
First Fall Frost September 28

Otter Tail County Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-6.8

Drainage

Well Drained

Shiso Planting Risk Windows

Early Start (70% safe) ✓ Fits season (15 days to spare)
Start indoors: Mar 3 Transplant: May 19 🍅 Harvest: Jul 14 – Sep 8
Recommended (50%) ✓ Fits season (7 days to spare)
Start indoors: Mar 16 Transplant: Jun 1 🍅 Harvest: Jul 27 – Sep 21
Safe Start (90%) ✓ Fits season (13 days to spare)
Start indoors: Mar 26 Transplant: Jun 11 🍅 Harvest: Aug 6 – Oct 1

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 Otter Tail County

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

Soil pH

Your soil pH (6.3–6.8) is within Shiso's preferred range (5.5–7.0).

Soil Texture

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

Drainage

Drainage is adequate for Shiso.

Organic Matter

Organic matter is excellent (5.2%) — Shiso will thrive.

How to Plant Shiso

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

Succession Planting Shiso

3
successive plantings in your 140-day season

Sow every 5.7 weeks. Last sowing by Jul 20 to harvest before frost.

Shiso Water Budget

Plant needs
1.0″/week
Rainfall provides
1.2″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 136 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 1.9" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 3.4" 0" ❄️ Dormant
May 4.3" 4.2" 0.1" 💧 Light watering
Jun 4.3" 5.7" 0" ✅ Rainfall sufficient
Jul 4.3" 5" 0" ✅ Rainfall sufficient
Aug 4.3" 4.3" 0" ✅ Rainfall sufficient
Sep 4.3" 3.1" 1.2" 💧 Light watering
Oct 3.4" 0" ❄️ Dormant
Nov 2.8" 0" ❄️ Dormant
Dec 2.4" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Otter Tail 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 ~600 GDD — county provides 1,400 GDD Excellent fit

Shiso Planting Timeline — Otter Tail County, MN

Shiso Planting Calendar

Activity When Date Range
Start Indoors March 16 Mar 16 – Mar 30
Transplant Outdoors June 1 Jun 1 – Jun 15
Direct Sow May 18 May 18 – Jun 8
Harvest July 27 Jul 27 – Sep 21

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April
May 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 · Only during dry spells

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 5.5–7 · Your soil: ideal

🗺️ USDA Zone

Zone 4a

📆 Growing Season

140 days in Otter Tail County

Growing Tips for Shiso in Otter Tail County

Direct sow Shiso outdoors after May 11 in Otter Tail 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 Otter Tail County, MN?

Otter Tail County is in Zone 4a with an average last frost of May 11. Plan your Shiso planting based on this frost date — see the calendar above for exact timing.

What planting zone is Otter Tail County, MN?

Otter Tail County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 11 and first fall frost is September 28.

When should I plant Shiso in Otter Tail County, MN?

In Otter Tail County, MN, plant Shiso after the last frost (around May 11) and before the first frost (around September 28). Best results when soil holds above 50°F.

What growing zone is Otter Tail County, MN for Shiso?

Otter Tail County sits in USDA Zone 4a. Shiso grows reliably in zones 3a through 11b, so it's a good fit here.

Can Shiso grow in Otter Tail County's climate?

Yes — Shiso grows well in Otter Tail County's temperate climate. Otter Tail County averages a 140-day frost-free season, with last frost around May 11 and first frost around September 28.

🌱

Your Otter Tail County Garden Planner — Free

A 22-page printable planner built for Otter Tail County (Zone 4a). 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 Otter Tail County, MN. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.