Blog

When to Plant Blackberries in Lake County, CO

Lake County, Colorado Zone 5a May

This month in Lake County, Colorado

Here's what deserves your attention in Lake County, Colorado this month. Everything below is tailored to Zone 5a and timed around your local frost dates.

Avg. last frost June 21
Avg. first frost August 30
Soil temp (4") 34°F
Watering High
Pest pressure Low
Daylight 14.1 hrs

Instant PDF download. No spam, unsubscribe any time.

Blackberries are vigorous bramble fruits that produce sweet-tart berries on thorny or thornless canes. They are prolific producers and relatively low-maintenance once established.

Lake County, Colorado is in USDA Zone 5a. The average last spring frost is June 21 and the first fall frost is August 30, giving you a growing season of approximately 70 days.

At an elevation of 7,687 feet, Lake County receives approximately 21.2 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Blackberries to ensure they mature before fall.

Lake County, CO (Zone 5a) Very short season
70 days
Last Spring Frost June 21
70 growing days
First Fall Frost August 30

Lake County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Transplant: Jul 7
Recommended (50%) ✓ Fits season
Transplant: Jul 12
Safe Start (90%) ✓ Fits season
Transplant: Jul 18

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 Lake County

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

Soil pH

Your soil pH (6.6–8.2) is more alkaline than Blackberries prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.9%). Annual compost additions will help Blackberries.

How to Plant Blackberries

24"
Between Plants
72"
Between Rows

Plant Water Budget

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

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Blackberries

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

Month Blackberries Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2.1" 0" ❄️ Dormant
May 2.7" 0" ❄️ Dormant
Jun 4.3" 1.4" 2.9" 🚿 Regular watering
Jul 4.3" 2.1" 2.2" 🚿 Regular watering
Aug 4.3" 2.2" 2.1" 💧 Light watering
Sep 1.6" 0" ❄️ Dormant
Oct 2.1" 0" ❄️ Dormant
Nov 1.6" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

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

Blackberries 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.

Blackberries needs ~6,707 GDD — county provides 857 GDD May not mature

Blackberries Planting Timeline — Lake County, CO

Blackberries Planting Calendar

Activity When Date Range
Transplant Outdoors July 12 Jul 12 – Jul 26

· 24" apart · Rows 72" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

365–730 days

🧪 Soil pH

Needs 5.5–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

70 days in Lake County

Growing Tips for Blackberries in Lake County

Direct sow Blackberries outdoors after June 21 in Lake County when soil has warmed and frost danger has passed.

Your 70.0-day growing season in Lake County is tight for Blackberries (365.0-730.0 days to maturity). Start indoors and choose early-maturing varieties.

Lake County receives only 21" of rain annually. Blackberries needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Plant bare-root canes in spring. Provide a sturdy trellis system. Prune out spent fruiting canes after harvest. New canes fruit in their second year (floricanes).

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Peppers

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Blackberries in Lake County, CO?

Lake County is in Zone 5a with an average last frost of June 21. Plan your Blackberries planting based on this frost date — see the calendar above for exact timing.

What planting zone is Lake County, CO?

Lake County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is June 21 and first fall frost is August 30.

🌱

Your Lake County Garden Planner — Free

A 24-page printable planner built for Lake County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Lake 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.