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When to Plant Cress in Rio Blanco County, CO

Rio Blanco County, Colorado Zone 5b May

Rio Blanco County, Colorado gardeners: here's your May plan

Welcome to May in Zone 5b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost June 2
Avg. first frost September 17
Soil temp (4") 37°F
Watering High
Pest pressure Low
Daylight 14.2 hrs
  1. Put cress seeds straight in the ground

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

Looking ahead to June
  • Transplants going out: cress
  • First harvests: cress

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Garden cress is one of the fastest-growing edibles, producing peppery sprouts in as little as two weeks. It is excellent for microgreens and garnishes.

Rio Blanco County, Colorado is in USDA Zone 5b. The average last spring frost is June 2 and the first fall frost is September 17, giving you a growing season of approximately 107 days.

At an elevation of 6,974 feet, Rio Blanco County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Cress during the growing season. With low rainfall, drip irrigation is essential for growing Cress successfully. Mulch heavily to conserve soil moisture.

Rio Blanco County, CO (Zone 5b) Short season
107 days
Last Spring Frost June 2
107 growing days
First Fall Frost September 17

Rio Blanco County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (77 days to spare)
Start indoors: Apr 14 Transplant: May 19 🍅 Harvest: Jun 2 – Jun 23
Recommended (50%) ✓ Fits season (72 days to spare)
Start indoors: Apr 28 Transplant: Jun 2 🍅 Harvest: Jun 16 – Jul 7
Safe Start (90%) ✓ Fits season (77 days to spare)
Start indoors: May 16 Transplant: Jun 20 🍅 Harvest: Jul 4 – Jul 25

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 Rio Blanco County

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

Soil pH

Your soil pH (6.4–7.7) is more alkaline than Cress prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Rio Blanco County is excellent for Cress — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Cress.

How to Plant Cress

0.5"
Planting Depth
2"
Between Plants
6"
Between Rows

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

Succession Planting Cress

9
successive plantings in your 107-day season

Sow every 1.6 weeks. Last sowing by Aug 27 to harvest before frost.

For a dedicated fall crop, sow by Jul 09.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 290 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Cress

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

Month Cress Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 2.1" 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" 1.6" 2.7" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 1.5" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

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

Cress 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.

Cress needs ~254 GDD — county provides 1,551 GDD Excellent fit

Cress Planting Timeline — Rio Blanco County, CO

Cress Planting Calendar

Activity When Date Range
Start Indoors April 28 Apr 28 – May 12
Transplant Outdoors June 2 Jun 2 – Jun 16
Direct Sow May 19 May 19 – Jun 9
Harvest June 16 Jun 16 – Jul 7
Fall Sowing July 9 Jul 9 – Jul 23

Plant 0.5" deep · 2" apart · Rows 6" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

14–21 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5b

📆 Growing Season

107 days in Rio Blanco County

Growing Tips for Cress in Rio Blanco County

Direct sow Cress outdoors after June 02 in Rio Blanco County when soil has warmed and frost danger has passed.

Your generous 107.0-day season in Rio Blanco County allows multiple plantings of Cress. Sow every 7.0 days for continuous harvest.

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

Rio Blanco County receives only 19" of rain annually. Cress needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Sow seeds thickly on moist soil or paper towels. Keep moist and harvest when 2-3 inches tall. Succession sow every few days for continuous supply. Grows well indoors year-round.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cress in Rio Blanco County, CO?

Rio Blanco County is in Zone 5b with an average last frost of June 2. Plan your Cress planting based on this frost date — see the calendar above for exact timing.

What planting zone is Rio Blanco County, CO?

Rio Blanco County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is June 2 and first fall frost is September 17.

🌱

Your Rio Blanco County Garden Planner — Free

A 24-page printable planner built for Rio Blanco 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 Rio Blanco 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.