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When to Plant Mitsuba in Archuleta County, CO

Archuleta County, Colorado Zone 5b May

Your May game plan for Archuleta County, Colorado

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Archuleta County, Colorado.

Avg. last frost June 13
Avg. first frost September 17
Soil temp (4") 46°F
Watering High
Pest pressure Low
Daylight 14 hrs
  1. Put mitsuba seeds straight in the ground

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

Coming up in June — start thinking about
  • Transplants going out: mitsuba

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Mitsuba (Japanese parsley) is a shade-loving herb with trefoil leaves and a mild celery-parsley flavor. It is essential in Japanese cuisine for soups, salads, and garnishes.

Archuleta County, Colorado is in USDA Zone 5b. 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 5,346 feet, Archuleta County receives approximately 14 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Mitsuba during the growing season. With low rainfall, drip irrigation is essential for growing Mitsuba successfully. Mulch heavily to conserve soil moisture.

Archuleta County, CO (Zone 5b) Very short season
96 days
Last Spring Frost June 13
96 growing days
First Fall Frost September 17
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Archuleta County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: May 2 Transplant: May 30 🍅 Harvest: Jul 25 – Sep 19
Recommended (50%) ✗ May not fit
Start indoors: May 9 Transplant: Jun 6 🍅 Harvest: Aug 1 – Sep 26
Safe Start (90%) ✗ May not fit
Start indoors: May 20 Transplant: Jun 17 🍅 Harvest: Aug 12 – Oct 7

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 Archuleta County

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

Soil pH

Your soil pH (6.3–7.9) is more alkaline than Mitsuba prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Archuleta County is excellent for Mitsuba — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Mitsuba.

How to Plant Mitsuba

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Mitsuba

2
successive plantings in your 96-day season

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

For a dedicated fall crop, sow by Jul 09.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 397 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Mitsuba

Mitsuba needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Mitsuba Needs Rainfall You Supplement Action
Jan 0.9" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1.1" 0" ❄️ Dormant
Apr 1.7" 0" ❄️ Dormant
May 1.9" 0" ❄️ Dormant
Jun 4.3" 1.1" 3.2" 🚿 Regular watering
Jul 4.3" 1.3" 3" 🚿 Regular watering
Aug 4.3" 1.3" 3" 🚿 Regular watering
Sep 4.3" 1.1" 3.2" 🚿 Regular watering
Oct 1.1" 0" ❄️ Dormant
Nov 0.9" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Archuleta County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Mitsuba 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.

Mitsuba needs ~825 GDD — county provides 1,320 GDD Excellent fit

Mitsuba Planting Timeline — Archuleta County, CO

Mitsuba Planting Calendar

Activity When Date Range
Start Indoors May 9 May 9 – May 23
Transplant Outdoors June 6 Jun 6 – Jun 20
Direct Sow May 30 May 30 – Jun 20
Harvest August 1 Aug 1 – Sep 26
Fall Sowing July 9 Jul 9 – Jul 23

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

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Start Indoors Direct Sow
June Transplant Outdoors Direct Sow
July Fall Sowing
August Harvest
September Harvest
October
November
December
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5b

📆 Growing Season

96 days in Archuleta County

Growing Tips for Mitsuba in Archuleta County

Direct sow Mitsuba outdoors after June 13 in Archuleta County when soil has warmed and frost danger has passed.

Common pests for Mitsuba in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

Archuleta County receives only 14" of rain annually. Mitsuba needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow or start indoors in partial shade. Mitsuba prefers cool, moist conditions. Harvest outer stems as needed. Self-sows readily in shaded garden areas.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mitsuba in Archuleta County, CO?

Archuleta County is in Zone 5b with an average last frost of June 13. Plan your Mitsuba planting based on this frost date — see the calendar above for exact timing.

What planting zone is Archuleta County, CO?

Archuleta County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is June 13 and first fall frost is September 17.

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Your Archuleta County Garden Planner — Free

A 24-page printable planner built for Archuleta County (Zone 5b). 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 Archuleta County, CO. 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.