When to Plant Shiso in Grand County, UT
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.
Grand County, Utah is in USDA Zone 6a. The average last spring frost is April 19 and the first fall frost is October 13, giving you a growing season of approximately 177 days.
At an elevation of 5,415 feet, Grand County receives approximately 23.1 inches of rainfall annually with predominantly loam soil. Summer highs average 91°F, providing good warmth for Shiso during the growing season.
Grand County Soil Profile
Soil Type
Loam
Soil pH
6.4-7.9
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 Grand County
How your county's soil matches Shiso's growing requirements.
Soil pH
Your soil pH (6.4–7.9) is more alkaline than Shiso prefers (5.5–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Grand County is excellent for Shiso — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Shiso.
Organic Matter
Organic matter is moderate (2.1%). Annual compost additions will help Shiso.
How to Plant Shiso
Succession Planting Shiso
Sow every 5.7 weeks. Last sowing by Aug 04 to harvest before frost.
Plant Water Budget
Water stress score is 8/10 — 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 | — | 1.6" | 0" | ❄️ Dormant |
| Feb | — | 1.3" | 0" | ❄️ Dormant |
| Mar | — | 2.2" | 0" | ❄️ Dormant |
| Apr | 4.3" | 2.2" | 2.1" | 💧 Light watering |
| May | 4.3" | 2.9" | 1.4" | 💧 Light watering |
| Jun | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Jul | 4.3" | 2.4" | 1.9" | 💧 Light watering |
| Aug | 4.3" | 2.1" | 2.2" | 🚿 Regular watering |
| Sep | 4.3" | 1.8" | 2.5" | 🚿 Regular watering |
| Oct | 4.3" | 2.1" | 2.2" | 🚿 Regular watering |
| Nov | — | 1.6" | 0" | ❄️ Dormant |
| Dec | — | 1.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Grand 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 — Grand County, UT
Shiso Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 1 | Mar 1 – Mar 15 |
| Transplant Outdoors | May 3 | May 3 – May 17 |
| Direct Sow | April 26 | Apr 26 – May 17 |
| Harvest | June 28 | Jun 28 – Aug 23 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | 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 · 2-3 times/week
📅 Days to Maturity
50–70 days
🧪 Soil pH
Needs 5.5–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 6a
📆 Growing Season
177 days in Grand County
Growing Tips for Shiso in Grand County
Direct sow Shiso outdoors after April 19 in Grand County when soil has warmed and frost danger has passed.
Grand County receives only 23" 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 →
Shiso in Other Locations
Frequently Asked Questions
When should I plant Shiso in Grand County, UT?
Grand County is in Zone 6a with an average last frost of April 19. Plan your Shiso planting based on this frost date — see the calendar above for exact timing.
What planting zone is Grand County, UT?
Grand County, Utah is in USDA Hardiness Zone 6a. The average last spring frost is April 19 and first fall frost is October 13.
Plan Your Garden with Confidence
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