When to Plant Shiso in El Paso County, CO
Your May game plan for El Paso County, Colorado
A quick May briefing for El Paso County, Colorado gardeners — what's urgent, what's next, and what can wait.
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Set out shiso seedlings
Frost risk is low now in El Paso County, Colorado. If you've been covering beds overnight, you can stop.
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Put shiso seeds straight in the ground
These tolerate cool soil, so you're not gambling by sowing now.
Coming up in June — start thinking about
- Starting indoors: 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.
El Paso County, Colorado is in USDA Zone 6a. The average last spring frost is May 11 and the first fall frost is October 6, giving you a growing season of approximately 148 days.
At an elevation of 8,317 feet, El Paso County receives approximately 23.5 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Shiso during the growing season.
El Paso County Soil Profile
Soil Type
Loam
Soil pH
6.5-7.9
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 El Paso County
How your county's soil matches Shiso's growing requirements.
Soil pH
Your soil pH (6.5–7.9) is more alkaline than Shiso prefers (5.5–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in El Paso County is excellent for Shiso — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.4%). Annual compost additions will help Shiso.
How to Plant Shiso
Succession Planting Shiso
Sow every 5.7 weeks. Last sowing by Jul 28 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 | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 1.8" | 0" | ❄️ Dormant |
| Apr | — | 2.4" | 0" | ❄️ Dormant |
| May | 4.3" | 2.8" | 1.5" | 💧 Light watering |
| Jun | 4.3" | 1.6" | 2.7" | 🚿 Regular watering |
| Jul | 4.3" | 2.3" | 2" | 💧 Light watering |
| Aug | 4.3" | 3" | 1.3" | 💧 Light watering |
| Sep | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Oct | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Nov | — | 1.5" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in El Paso 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 — El Paso County, CO
Shiso Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 23 | Mar 23 – Apr 6 |
| Transplant Outdoors | May 25 | May 25 – Jun 8 |
| Direct Sow | May 18 | May 18 – Jun 8 |
| Harvest | July 20 | Jul 20 – Sep 14 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| 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
148 days in El Paso County
Growing Tips for Shiso in El Paso County
Direct sow Shiso outdoors after May 11 in El Paso County when soil has warmed and frost danger has passed.
El Paso County receives only 24" 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 El Paso County, CO?
El Paso County is in Zone 6a 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 El Paso County, CO?
El Paso County, Colorado is in USDA Hardiness Zone 6a. The average last spring frost is May 11 and first fall frost is October 6.
Your El Paso County Garden Planner — Free
A 24-page printable planner built for El Paso 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.