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When to Plant Angelica in Roosevelt County, MT

Roosevelt County, Montana Zone 4a May

Your May game plan for Roosevelt County, Montana

Here's what deserves your attention in Roosevelt County, Montana this month. Everything below is tailored to Zone 4a and timed around your local frost dates.

Avg. last frost May 17
Avg. first frost September 18
Soil temp (4") 28°F
Watering High
Pest pressure Low
Daylight 15 hrs
  1. Move angelica from tray to bed

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Outdoor sowing time: angelica

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

Get ahead of June
  • Starting indoors: angelica
  • Fall sowing: angelica

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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.

Roosevelt County, Montana is in USDA Zone 4a. The average last spring frost is May 17 and the first fall frost is September 18, giving you a growing season of approximately 124 days.

At an elevation of 7,123 feet, Roosevelt County receives approximately 19.8 inches of rainfall annually with predominantly loam soil. Summer highs average 78°F, so choose short-season varieties of Angelica to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Angelica successfully. Mulch heavily to conserve soil moisture.

Roosevelt County, MT (Zone 4a) Short season
124 days
Last Spring Frost May 17
124 growing days
First Fall Frost September 18

Roosevelt County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Start indoors: Apr 1 Transplant: May 6
Recommended (50%) ✓ Fits season
Start indoors: Apr 5 Transplant: May 10
Safe Start (90%) ✓ Fits season
Start indoors: Apr 22 Transplant: May 27

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 Roosevelt County

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

Soil pH

Your soil pH (6.7–7.7) is more alkaline than Angelica prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help Angelica.

How to Plant Angelica

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.7″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 1,098 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 1.6" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 6.5" 2.3" 4.2" 🚿 Regular watering
Jun 6.5" 1.5" 5" 🚿 Regular watering
Jul 6.5" 1.6" 4.9" 🚿 Regular watering
Aug 6.5" 1.9" 4.6" 🚿 Regular watering
Sep 6.5" 1.7" 4.8" 🚿 Regular watering
Oct 1.8" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Roosevelt 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 ~4,654 GDD — county provides 1,054 GDD May not mature

Angelica Planting Timeline — Roosevelt County, MT

Angelica Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 10 May 10 – May 24
Direct Sow May 10 May 10 – May 31
Fall Sowing June 26 Jun 26 – Jul 10

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

Month-by-Month Timeline

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

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 4a

📆 Growing Season

124 days in Roosevelt County

Growing Tips for Angelica in Roosevelt County

Direct sow Angelica outdoors after May 17 in Roosevelt County when soil has warmed and frost danger has passed.

Your 124.0-day growing season in Roosevelt 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.

Roosevelt County receives only 20" 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 Roosevelt County, MT?

Roosevelt County is in Zone 4a with an average last frost of May 17. Plan your Angelica planting based on this frost date — see the calendar above for exact timing.

What planting zone is Roosevelt County, MT?

Roosevelt County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 17 and first fall frost is September 18.

🌱

Your Roosevelt County Garden Planner — Free

A 24-page printable planner built for Roosevelt County (Zone 4a). 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 Roosevelt County, MT. 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.