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When to Plant Pac Choi in Pitkin County, CO

Pitkin County, Colorado Zone 5a May

What to do in May

Here's what deserves your attention in Pitkin County, Colorado this month. Everything below is tailored to Zone 5a and timed around your local frost dates.

Avg. last frost June 16
Avg. first frost September 7
Soil temp (4") 36°F
Watering High
Pest pressure Low
Daylight 14.1 hrs
Looking ahead to June
  • Transplants going out: pac choi
  • Direct-sowing: pac choi
  • Fall sowing: pac choi

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Pac choi (baby bok choy) is a compact variety of Chinese cabbage with tender leaves and crisp stems. It grows quickly and is ideal for containers and small spaces.

Pitkin County, Colorado is in USDA Zone 5a. The average last spring frost is June 16 and the first fall frost is September 7, giving you a growing season of approximately 83 days.

At an elevation of 6,411 feet, Pitkin County receives approximately 17.8 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Pac Choi to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Pac Choi successfully. Mulch heavily to conserve soil moisture.

Pitkin County, CO (Zone 5a) Very short season
83 days
Last Spring Frost June 16
83 growing days
First Fall Frost September 7
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Pitkin County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (13 days to spare)
Start indoors: May 1 Transplant: Jun 5 🍅 Harvest: Jul 17 – Aug 14
Recommended (50%) ✓ Fits season (13 days to spare)
Start indoors: May 12 Transplant: Jun 16 🍅 Harvest: Jul 28 – Aug 25
Safe Start (90%) ✓ Fits season (32 days to spare)
Start indoors: May 23 Transplant: Jun 27 🍅 Harvest: Aug 8 – Sep 5

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 Pitkin County

How your county's soil matches Pac Choi's growing requirements.

Soil pH

Your soil pH (6.6–8.3) overlaps with Pac Choi's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Pitkin County is excellent for Pac Choi — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

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

How to Plant Pac Choi

1"
Planting Depth
15"
Between Plants
24"
Between Rows

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

Succession Planting Pac Choi

2
successive plantings in your 83-day season

Sow every 4.6 weeks. Last sowing by Jul 14 to harvest before frost.

For a dedicated fall crop, sow by Jun 29.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.9″/week
You supply
0.7″/week
Watering frequency 2-3 times/week
Season total 531 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Pac Choi

Pac Choi needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Pac Choi Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 1.9" 0" ❄️ Dormant
May 2" 0" ❄️ Dormant
Jun 6.5" 1.3" 5.2" 🚿 Regular watering
Jul 6.5" 1.4" 5.1" 🚿 Regular watering
Aug 6.5" 1.9" 4.6" 🚿 Regular watering
Sep 6.5" 1.7" 4.8" 🚿 Regular watering
Oct 1.5" 0" ❄️ Dormant
Nov 1.1" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

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

Pac Choi 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.

Pac Choi needs ~546 GDD — county provides 954 GDD Excellent fit

Pac Choi Planting Timeline — Pitkin County, CO

Pac Choi Planting Calendar

Activity When Date Range
Start Indoors May 12 May 12 – May 26
Transplant Outdoors June 16 Jun 16 – Jun 30
Direct Sow June 2 Jun 2 – Jun 23
Harvest July 28 Jul 28 – Aug 25
Fall Sowing June 29 Jun 29 – Jul 13

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1.5"/week · 2-3 times/week

📅 Days to Maturity

40–55 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

83 days in Pitkin County

Growing Tips for Pac Choi in Pitkin County

Direct sow Pac Choi outdoors after June 16 in Pitkin County when soil has warmed and frost danger has passed.

Common pests for Pac Choi in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

Pitkin County receives only 18" of rain annually. Pac Choi needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow in spring or fall. Grows best in cool weather. Space 6 inches apart for baby pac choi. Harvest whole plants or cut outer leaves as needed.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Pac Choi in Pitkin County, CO?

Pitkin County is in Zone 5a with an average last frost of June 16. Plan your Pac Choi planting based on this frost date — see the calendar above for exact timing.

What planting zone is Pitkin County, CO?

Pitkin County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is June 16 and first fall frost is September 7.

🌱

Your Pitkin County Garden Planner — Free

A 24-page printable planner built for Pitkin County (Zone 5a). 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 Pitkin 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.