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When to Plant Angelica in Rio Blanco County, CO

Rio Blanco County, Colorado Zone 5b May

Your May planting checklist for Rio Blanco County, Colorado

May is a pivotal month for Rio Blanco County, Colorado gardens. Focus on these tasks first and you'll set up the rest of the season for success.

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. Time to transplant angelica

    Frost risk is low now in Rio Blanco County, Colorado. If you've been covering beds overnight, you can stop.

  2. Plant angelica from seed, right in the garden

    Your soil is 37°F — warm enough for these to germinate without babying.

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Angelica is a dramatic biennial herb that can reach 6 feet tall with large compound leaves and globe-shaped flower clusters. All parts are edible with a sweet, celery-like flavor.

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 Angelica during the growing season. With low rainfall, drip irrigation is essential for growing Angelica 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
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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
Start indoors: Apr 14 Transplant: May 12
Recommended (50%) ✓ Fits season
Start indoors: Apr 28 Transplant: May 26
Safe Start (90%) ✓ Fits season
Start indoors: May 16 Transplant: Jun 13

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 Angelica's growing requirements.

Soil pH

Your soil pH (6.4–7.7) is more alkaline than Angelica prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

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

How to Plant Angelica

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

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

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.8″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 862 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Angelica

Angelica 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 Angelica 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 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" 1.6" 4.9" 🚿 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.

Angelica 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.

Angelica needs ~7,939 GDD — county provides 1,551 GDD May not mature

Angelica Planting Timeline — Rio Blanco County, CO

Angelica Planting Calendar

Activity When Date Range
Start Indoors April 28 Apr 28 – May 12
Transplant Outdoors May 26 May 26 – Jun 9
Direct Sow May 19 May 19 – Jun 9
Fall Sowing July 9 Jul 9 – Jul 23

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Start Indoors Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July Fall Sowing
August
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

365–730 days

🧪 Soil pH

Needs 5.5–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5b

📆 Growing Season

107 days in Rio Blanco County

Growing Tips for Angelica in Rio Blanco County

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

Your 107.0-day growing season in Rio Blanco County is tight for Angelica (365.0-730.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Angelica in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

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

General growing tips

Sow fresh seeds in fall for spring germination. Provide rich, moist soil and partial shade. Harvest stems in the second year before flowering for candying or flavoring.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

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

Rio Blanco County is in Zone 5b with an average last frost of June 2. Plan your Angelica 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.

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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.