Blog

When to Plant Zucchini in Alamosa County, CO

Alamosa County, Colorado Zone 5a May

What to do in May

We've pulled the most time-sensitive tasks for Alamosa County, Colorado this May and put them front and centre. Tackle them in order.

Avg. last frost May 31
Avg. first frost September 19
Soil temp (4") 28°F
Watering High
Pest pressure Low
Daylight 14 hrs
Before June arrives, get these ready
  • Transplants going out: zucchini
  • Direct-sowing: zucchini

Instant PDF download. No spam, unsubscribe any time.

Zucchini is an incredibly prolific summer squash that can produce an abundance of fruit from just a few plants. It is versatile in the kitchen from grilling to baking.

Alamosa County, Colorado is in USDA Zone 5a. The average last spring frost is May 31 and the first fall frost is September 19, giving you a growing season of approximately 111 days.

At an elevation of 8,366 feet, Alamosa County receives approximately 18.3 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Zucchini to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Zucchini successfully. Mulch heavily to conserve soil moisture.

Alamosa County, CO (Zone 5a) Short season
111 days
Last Spring Frost May 31
111 growing days
First Fall Frost September 19
Share this guide:

Alamosa County Soil Profile

Soil Type

Loam

Soil pH

6.4-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 21 Transplant: Jun 9 🍅 Harvest: Jul 28 – Sep 22
Recommended (50%) ✗ May not fit
Start indoors: Apr 26 Transplant: Jun 14 🍅 Harvest: Aug 2 – Sep 27
Safe Start (90%) ✗ May not fit
Start indoors: May 10 Transplant: Jun 28 🍅 Harvest: Aug 16 – Oct 11

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 Alamosa County

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

Soil pH

Your soil pH (6.4–8.0) overlaps with Zucchini's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Zucchini.

How to Plant Zucchini

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

Succession Planting Zucchini

2
successive plantings in your 111-day season

Sow every 5.1 weeks. Last sowing by Jul 21 to harvest before frost.

Plant Water Budget

Plant needs
1.2″/week
Rainfall provides
0.7″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 602 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Zucchini

Zucchini needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.

Month Zucchini Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 1.9" 0" ❄️ Dormant
May 5.2" 2" 3.2" 🚿 Regular watering
Jun 5.2" 1.5" 3.7" 🚿 Regular watering
Jul 5.2" 1.5" 3.7" 🚿 Regular watering
Aug 5.2" 1.9" 3.3" 🚿 Regular watering
Sep 5.2" 1.4" 3.8" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 1.6" 0" ❄️ Dormant
Dec 1" 0" ❄️ Dormant

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

Zucchini 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.

Zucchini needs ~564 GDD — county provides 1,193 GDD Excellent fit

Zucchini Planting Timeline — Alamosa County, CO

Zucchini Planting Calendar

Activity When Date Range
Start Indoors April 26 Apr 26 – May 10
Transplant Outdoors June 14 Jun 14 – Jun 28
Direct Sow June 7 Jun 7 – Jun 28
Harvest August 2 Aug 2 – Sep 27

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.2"/week · 1-2 times/week

📅 Days to Maturity

45–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

111 days in Alamosa County

Growing Tips for Zucchini in Alamosa County

Direct sow Zucchini outdoors after May 31 in Alamosa County when soil has warmed and frost danger has passed.

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

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

General growing tips

Direct sow after last frost. Harvest when fruits are 6-8 inches long for best flavor and texture. Check plants daily in summer as fruits can double in size overnight.

Recommended Zucchini Varieties for Alamosa County

Quick-producing varieties for shorter seasons

Black Beauty (50d) Raven (48d) Eight Ball (40d)

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Zucchini in Alamosa County, CO?

Alamosa County is in Zone 5a with an average last frost of May 31. Plan your Zucchini planting based on this frost date — see the calendar above for exact timing.

What planting zone is Alamosa County, CO?

Alamosa County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is May 31 and first fall frost is September 19.

🌱

Your Alamosa County Garden Planner — Free

A 24-page printable planner built for Alamosa 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Alamosa 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.