When to Plant Shiso in Franklin County, IL
This month in Franklin County, Illinois
Here's what deserves your attention in Franklin County, Illinois this month. Everything below is tailored to Zone 7a and timed around your local frost dates.
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Start shiso under lights
Your window is short. These crops want several weeks of indoor growth before they go outside.
Get ahead of June
- First harvests: shiso
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.
Franklin County, Illinois is in USDA Zone 7a. The average last spring frost is April 10 and the first fall frost is October 20, giving you a growing season of approximately 193 days.
At an elevation of 747 feet, Franklin County receives approximately 37.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Shiso during the growing season.
Franklin County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-7.1
Drainage
Well Drained
Plant Planting Risk Windows
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 Franklin County
How your county's soil matches Shiso's growing requirements.
Soil pH
Your soil pH (5.9–7.1) overlaps with Shiso's range (5.5–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Franklin County is excellent for Shiso — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.3%) — Shiso will thrive.
How to Plant Shiso
Succession Planting Shiso
Sow every 5.7 weeks. Last sowing by Aug 11 to harvest before frost.
Plant Water Budget
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 | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.7" | 0" | ❄️ Dormant |
| Mar | — | 2.7" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| May | 4.3" | 4.4" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Aug | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Sep | 4.3" | 2.9" | 1.4" | 💧 Light watering |
| Oct | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 2.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Franklin 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 Planting Timeline — Franklin County, IL
Shiso Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 20 | Feb 20 – Mar 6 |
| Transplant Outdoors | April 24 | Apr 24 – May 8 |
| Direct Sow | April 17 | Apr 17 – May 8 |
| Harvest | June 19 | Jun 19 – Aug 14 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| 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: acceptable
🗺️ USDA Zone
Zone 7a
📆 Growing Season
193 days in Franklin County
Growing Tips for Shiso in Franklin County
Direct sow Shiso outdoors after April 10 in Franklin 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 →
Shiso in Other Locations
Frequently Asked Questions
When should I plant Shiso in Franklin County, IL?
Franklin County is in Zone 7a with an average last frost of April 10. Plan your Shiso planting based on this frost date — see the calendar above for exact timing.
What planting zone is Franklin County, IL?
Franklin County, Illinois is in USDA Hardiness Zone 7a. The average last spring frost is April 10 and first fall frost is October 20.
Your Franklin County Garden Planner — Free
A 24-page printable planner built for Franklin 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.