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When to Plant Squash (Summer) in Pitkin County, CO

Pitkin County, Colorado Zone 5a May

Pitkin County, Colorado gardeners: here's your May plan

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

Avg. last frost June 16
Avg. first frost September 7
Soil temp (4") 36°F
Watering High
Pest pressure Low
Daylight 14.1 hrs
June prep starts now
  • Transplants going out: squash (summer)
  • Direct-sowing: squash (summer)

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Summer squash includes zucchini, yellow crookneck, and pattypan varieties that are harvested young and tender. They are prolific producers in warm weather.

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 Squash (Summer) to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Squash (Summer) 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

Pitkin County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: May 1 Transplant: Jun 19 🍅 Harvest: Aug 7 – Oct 9
Recommended (50%) ✗ May not fit
Start indoors: May 12 Transplant: Jun 30 🍅 Harvest: Aug 18 – Oct 20
Safe Start (90%) ✗ May not fit
Start indoors: May 23 Transplant: Jul 11 🍅 Harvest: Aug 29 – Oct 31

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 Squash (Summer)'s growing requirements.

Soil pH

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

Soil Texture

The loam soil in Pitkin County is excellent for Squash (Summer) — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

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

How to Plant Squash (Summer)

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Squash (Summer)

2
successive plantings in your 83-day season

Sow every 5.1 weeks. Last sowing by Jul 04 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 88 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Squash (Summer)

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

Month Squash (Summer) 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 4.3" 1.3" 3" 🚿 Regular watering
Jul 4.3" 1.4" 2.9" 🚿 Regular watering
Aug 4.3" 1.9" 2.4" 🚿 Regular watering
Sep 4.3" 1.7" 2.6" 🚿 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.

Squash (Summer) 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.

Squash (Summer) needs ~632 GDD — county provides 954 GDD Excellent fit

Squash (Summer) Planting Timeline — Pitkin County, CO

Squash (Summer) Planting Calendar

Activity When Date Range
Start Indoors May 12 May 12 – May 26
Transplant Outdoors June 30 Jun 30 – Jul 14
Direct Sow June 23 Jun 23 – Jul 14
Harvest August 18 Aug 18 – Oct 20

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

45–65 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

83 days in Pitkin County

Growing Tips for Squash (Summer) in Pitkin County

Direct sow Squash (Summer) outdoors after June 16 in Pitkin County when soil has warmed and frost danger has passed.

Common pests for Squash (Summer) in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

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

General growing tips

Direct sow after last frost on mounds. Harvest frequently when fruits are 6-8 inches for best texture. Check plants daily as they grow rapidly in summer heat.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Squash (Summer) in Pitkin County, CO?

Pitkin County is in Zone 5a with an average last frost of June 16. Plan your Squash (Summer) 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.