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When to Plant Shiso in Rio Arriba County, NM

Rio Arriba County, New Mexico Zone 7a May

Your May game plan for Rio Arriba County, New Mexico

Your garden in Rio Arriba County, New Mexico is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost June 13
Avg. first frost September 17
Soil temp (4") 44°F
Watering Critical
Pest pressure Low
Daylight 13.9 hrs
Get ahead of June
  • Transplants going out: shiso
  • Direct-sowing: 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.

Rio Arriba County, New Mexico is in USDA Zone 7a. The average last spring frost is June 13 and the first fall frost is September 17, giving you a growing season of approximately 96 days.

At an elevation of 5,979 feet, Rio Arriba County receives approximately 17.4 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 84°F, so choose short-season varieties of Shiso to ensure they mature before fall. Sandy soil warms quickly in spring — great for early planting — but Shiso will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Shiso successfully. Mulch heavily to conserve soil moisture.

Rio Arriba County, NM (Zone 7a) Very short season
96 days
Last Spring Frost June 13
96 growing days
First Fall Frost September 17

Rio Arriba County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.3-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 18 Transplant: Jun 20 🍅 Harvest: Aug 15 – Oct 10
Recommended (50%) ✗ May not fit
Start indoors: Apr 25 Transplant: Jun 27 🍅 Harvest: Aug 22 – Oct 17
Safe Start (90%) ✗ May not fit
Start indoors: May 6 Transplant: Jul 8 🍅 Harvest: Sep 2 – Oct 28

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 Rio Arriba County

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

Soil pH

Your soil pH (7.3–8.1) is more alkaline than Shiso prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Sandy soil in Rio Arriba County warms quickly in spring but drains fast. Shiso will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Shiso.

Organic Matter

Organic matter is low (0.8%). Add 2-3 inches of compost before planting Shiso.

How to Plant Shiso

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

Succession Planting Shiso

2
successive plantings in your 96-day season

Sow every 5.7 weeks. Last sowing by Jul 09 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 552 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — 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 1.1" 0" ❄️ Dormant
Mar 0.9" 0" ❄️ Dormant
Apr 0.6" 0" ❄️ Dormant
May 0.5" 0" ❄️ Dormant
Jun 4.3" 0.5" 3.8" 🚿 Regular watering
Jul 4.3" 2.6" 1.7" 💧 Light watering
Aug 4.3" 3.3" 1" 💧 Light watering
Sep 4.3" 2.6" 1.7" 💧 Light watering
Oct 1.4" 0" ❄️ Dormant
Nov 1.2" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Rio Arriba 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 ~780 GDD — county provides 1,248 GDD Excellent fit

Shiso Planting Timeline — Rio Arriba County, NM

Shiso Planting Calendar

Activity When Date Range
Start Indoors April 25 Apr 25 – May 9
Transplant Outdoors June 27 Jun 27 – Jul 11
Direct Sow June 20 Jun 20 – Jul 11
Harvest August 22 Aug 22 – Oct 17

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Start Indoors
June Transplant Outdoors Direct Sow
July Transplant Outdoors Direct Sow
August Harvest
September Harvest
October Harvest
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 7a

📆 Growing Season

96 days in Rio Arriba County

Growing Tips for Shiso in Rio Arriba County

Direct sow Shiso outdoors after June 13 in Rio Arriba County when soil has warmed and frost danger has passed.

Sandy soil in Rio Arriba County dries quickly — mulch Shiso with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

Rio Arriba County receives only 17" 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 Rio Arriba County, NM?

Rio Arriba County is in Zone 7a with an average last frost of June 13. Plan your Shiso planting based on this frost date — see the calendar above for exact timing.

What planting zone is Rio Arriba County, NM?

Rio Arriba County, New Mexico is in USDA Hardiness Zone 7a. The average last spring frost is June 13 and first fall frost is September 17.

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Your Rio Arriba County Garden Planner — Free

A 24-page printable planner built for Rio Arriba 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.

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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 Rio Arriba County, NM. 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.