When to plant Broccoli in Summit County, CO
In Zone 5a (Summit County), direct-sow Broccoli between June 2 and June 23 for spring, after the June 16 last-frost mark. A second sowing from June 26 to July 10 extends the harvest into fall.
When to Plant Broccoli in Summit County, CO
Broccoli is a nutrient-dense cool-season crop that produces large central heads followed by smaller side shoots. It is one of the most popular garden vegetables.
Summit County, Colorado is in USDA Zone 5a. The average last spring frost is June 16 and the first fall frost is September 4, giving you a growing season of approximately 80 days.
At an elevation of 7,005 feet, Summit County receives approximately 17.5 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Broccoli to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Broccoli successfully. Mulch heavily to conserve soil moisture.
Summit County Soil Profile
Soil Type
Loam
Soil pH
6.8-8
Drainage
Well Drained
How Much Broccoli to Grow
For a family of 4, plant approximately 12 broccoli plants in about 24 sq ft. In Summit County's 80-day season, you'll have plenty of time for a full harvest. Plan your garden layout →
Monthly Watering Guide for Broccoli
Broccoli needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Broccoli Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.1" | 0" | ❄️ Dormant |
| Mar | — | 1.6" | 0" | ❄️ Dormant |
| Apr | — | 1.7" | 0" | ❄️ Dormant |
| May | — | 1.8" | 0" | ❄️ Dormant |
| Jun | 4.3" | 1.3" | 3" | 🚿 Regular watering |
| Jul | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Aug | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Sep | 4.3" | 1.3" | 3" | 🚿 Regular watering |
| Oct | — | 1.6" | 0" | ❄️ Dormant |
| Nov | — | 1.2" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Summit County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Broccoli Planting Timeline — Summit County, CO
Broccoli Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | May 12 | May 12 – May 26 |
| Transplant Outdoors | June 16 | Jun 16 – Jun 30 |
| Direct Sow | June 2 | Jun 2 – Jun 23 |
| Harvest | August 18 | Aug 18 – Sep 29 |
| Fall Sowing | June 26 | Jun 26 – Jul 10 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Start Indoors |
| June | Transplant Outdoors Direct Sow Fall Sowing |
| July | Fall Sowing |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 5a
📆 Growing Season
80 days in Summit County
Growing Tips for Summit County
Start seeds indoors 6-8 weeks before last frost. Provide consistent moisture to prevent hollow stems. Harvest heads before yellow flowers appear.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Isolate 1/2 mile from other brassicas. Biennial — must overwinter roots.
Broccoli in Other Locations
Frequently Asked Questions
When should I plant Broccoli in Summit County, CO?
Summit County is in Zone 5a with an average last frost of June 16. Plan your Broccoli planting based on this frost date — see the calendar above for exact timing.
What planting zone is Summit County, CO?
Summit County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is June 16 and first fall frost is September 4.
When should I plant Broccoli in Summit County, CO?
In Summit County, CO, plant Broccoli after the last frost (around June 16) and before the first frost (around September 4). Best results when soil holds above 50°F.
What growing zone is Summit County, CO for Broccoli?
Summit County sits in USDA Zone 5a. Broccoli grows reliably in zones 2a through 11b, so it's a good fit here.
Can Broccoli grow in Summit County's climate?
Yes — Broccoli grows well in Summit County's temperate climate. Summit County averages a 80-day frost-free season, with last frost around June 16 and first frost around September 4.
Your Summit County Garden Planner — Free
A 22-page printable planner built for Summit 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.