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When to Plant Tomatoes in Dolores County, CO

Dolores County, Colorado Zone 6b May

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

Welcome to May in Zone 6b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost June 18
Avg. first frost September 8
Soil temp (4") 38°F
Watering Moderate
Pest pressure Low
Daylight 14 hrs
Looking ahead to June
  • Direct-sowing: tomatoes

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Tomatoes are the most popular home garden crop, available in thousands of varieties from tiny cherries to massive beefsteaks. They are warm-season plants needing full sun.

Dolores County, Colorado is in USDA Zone 6b. The average last spring frost is June 18 and the first fall frost is September 8, giving you a growing season of approximately 82 days.

At an elevation of 7,506 feet, Dolores County receives approximately 23.1 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Tomatoes during the growing season.

Dolores County, CO (Zone 6b) Very short season
82 days
Last Spring Frost June 18
82 growing days
First Fall Frost September 8

Dolores County Soil Profile

Soil Type

Loam

Soil pH

6.3-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 12 Transplant: Jun 21 🍅 Harvest: Aug 23 – Nov 1
Recommended (50%) ✗ May not fit
Start indoors: Apr 23 Transplant: Jul 2 🍅 Harvest: Sep 3 – Nov 12
Safe Start (90%) ✗ May not fit
Start indoors: May 4 Transplant: Jul 13 🍅 Harvest: Sep 14 – Nov 23

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 Dolores County

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

Soil pH

Your soil pH (6.3–8.3) is more alkaline than Tomatoes prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.8%). Annual compost additions will help Tomatoes.

How to Plant Tomatoes

0.5"
Planting Depth
24"
Between Plants
36"
Between Rows

How Much Tomatoes to Grow

10-15 lbs
Average yield per plant
3
Plants per person
18 sq ft
Space per person

For a family of 4, plant approximately 12 tomatoes plants in about 72 sq ft. In Dolores County's 82-day season, you'll have plenty of time for a full harvest. Plan your garden layout →

Plant Water Budget

Plant needs
1.2″/week
Rainfall provides
1.2″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 15 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Tomatoes

Tomatoes 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 Tomatoes Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 2.6" 0" ❄️ Dormant
May 3" 0" ❄️ Dormant
Jun 5.2" 1.8" 3.4" 🚿 Regular watering
Jul 5.2" 1.9" 3.3" 🚿 Regular watering
Aug 5.2" 2.1" 3.1" 🚿 Regular watering
Sep 5.2" 2.1" 3.1" 🚿 Regular watering
Oct 2.2" 0" ❄️ Dormant
Nov 1.7" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

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

Tomatoes 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.

Tomatoes needs ~997 GDD — county provides 1,127 GDD Good fit

Tomatoes Planting Timeline — Dolores County, CO

Tomatoes Planting Calendar

Activity When Date Range
Start Indoors April 23 Apr 23 – May 7
Transplant Outdoors July 2 Jul 2 – Jul 16
Direct Sow June 25 Jun 25 – Jul 16
Harvest September 3 Sep 3 – Nov 12

Plant 0.5" deep · 24" apart · Rows 36" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.2"/week · Only during dry spells

📅 Days to Maturity

60–85 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6b

📆 Growing Season

82 days in Dolores County

Growing Tips for Tomatoes in Dolores County

Direct sow Tomatoes outdoors after June 18 in Dolores County when soil has warmed and frost danger has passed.

Your 82.0-day growing season in Dolores County is tight for Tomatoes (60.0-85.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Tomatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

Dolores County receives only 23" of rain annually. Tomatoes needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start seeds indoors 6-8 weeks before last frost. Bury transplants deep to encourage rooting along the stem. Provide consistent moisture to prevent blossom end rot and cracking.

Recommended Tomatoes Varieties for Dolores County

Choose determinate, early-maturing varieties for your short season

Early Girl (52d) Stupice (55d) Glacier (55d) Sub Arctic Plenty (45d)

Companion Planting

Good Companions

Avoid Planting Near

  • Cabbage
  • Fennel
  • Potatoes

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Tomatoes Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Scoop seeds from ripe fruit; ferment 2-3 days to remove gel coating.
Storage Store airtight; viable 4-6 years at 35°F, under 45% humidity.

Isolate 25 ft between varieties for purity. Use open-pollinated varieties for true-to-type seeds.

Frequently Asked Questions

When should I plant Tomatoes in Dolores County, CO?

Dolores County is in Zone 6b with an average last frost of June 18. Plan your Tomatoes planting based on this frost date — see the calendar above for exact timing.

What planting zone is Dolores County, CO?

Dolores County, Colorado is in USDA Hardiness Zone 6b. The average last spring frost is June 18 and first fall frost is September 8.

🌱

Your Dolores County Garden Planner — Free

A 24-page printable planner built for Dolores County (Zone 6b). 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 Dolores 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.