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When to Plant Lavender in Larimer County, CO

Larimer County, Colorado Zone 5b May

Your May planting checklist for Larimer County, Colorado

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

Avg. last frost May 2
Avg. first frost October 6
Soil temp (4") 36°F
Watering High
Pest pressure Low
Daylight 14.3 hrs
  1. Move lavender from tray to bed

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

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Lavender is a fragrant perennial herb with silvery foliage and purple flower spikes. It is prized for its essential oils, culinary uses, and ornamental beauty.

Larimer County, Colorado is in USDA Zone 5b. The average last spring frost is May 2 and the first fall frost is October 6, giving you a growing season of approximately 157 days.

At an elevation of 7,108 feet, Larimer County receives approximately 23.4 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Lavender to ensure they mature before fall.

Larimer County, CO (Zone 5b) Moderate season
157 days
Last Spring Frost May 2
157 growing days
First Fall Frost October 6
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Larimer County Soil Profile

Soil Type

Loam

Soil pH

6.4-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 5 🍅 Harvest: Aug 4 – Oct 20
Recommended (50%) ✗ May not fit
Transplant: May 9 🍅 Harvest: Aug 8 – Oct 24
Safe Start (90%) ✗ May not fit
Transplant: May 28 🍅 Harvest: Aug 27 – Nov 12

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 Larimer County

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

Soil pH

Your soil pH (6.4–8.2) overlaps with Lavender's range (6.5–8.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Lavender.

Organic Matter

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

How to Plant Lavender

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

Plant Water Budget

Plant needs
0.3″/week
Rainfall provides
0.6″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Lavender

Lavender needs approximately 0.3 inches of water per week (1.3" per month). Here's how your county's rainfall compares month by month.

Month Lavender Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 2.2" 0" ❄️ Dormant
May 1.3" 2.5" 0" ✅ Rainfall sufficient
Jun 1.3" 1.9" 0" ✅ Rainfall sufficient
Jul 1.3" 2.3" 0" ✅ Rainfall sufficient
Aug 1.3" 2.5" 0" ✅ Rainfall sufficient
Sep 1.3" 2" 0" ✅ Rainfall sufficient
Oct 1.3" 1.9" 0" ✅ Rainfall sufficient
Nov 1.7" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

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

Lavender 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.

Lavender needs ~1,885 GDD — county provides 2,041 GDD Good fit

Lavender Planting Timeline — Larimer County, CO

Lavender Planting Calendar

Activity When Date Range
Transplant Outdoors May 9 May 9 – May 23
Harvest August 8 Aug 8 – Oct 24

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

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Transplant Outdoors
June
July
August Harvest
September Harvest
October Harvest
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.3"/week · Natural rainfall sufficient

📅 Days to Maturity

90–200 days

🧪 Soil pH

Needs 6.5–8 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

157 days in Larimer County

Growing Tips for Lavender in Larimer County

Direct sow Lavender outdoors after May 02 in Larimer County when soil has warmed and frost danger has passed.

Your 157.0-day growing season in Larimer County is tight for Lavender (90.0-200.0 days to maturity). Start indoors and choose early-maturing varieties.

General growing tips

Plant in well-drained, sandy soil. Avoid heavy mulching around the crown. Prune after flowering but do not cut into old wood. Lavender resents wet winter conditions.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lavender in Larimer County, CO?

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

What planting zone is Larimer County, CO?

Larimer County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 2 and first fall frost is October 6.

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Your Larimer County Garden Planner — Free

A 24-page printable planner built for Larimer 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 Larimer 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.