đ„ŠWhen to Plant Broccoli in USDA Zone 5b (2026 Guide)
Cool-season brassica. Transplant before the last frost for spring crops. Here is the cool-season planting schedule for broccoli in zone 5b (covering areas like Denver CO, Columbus OH). All dates are based on 2026 frost data for your zone.
Start Seeds Indoors
Mar 21
Transplant
Apr 11
Harvest From
Jun 15
Because broccoli is a cool-season crop, it tolerates light frost and can go out around Apr 11, before zone 5b's average last frost on Apr 25.
- Type: Cool-season
- Method: Transplant
- Days to harvest: 65
- Spacing: 18" apart
- Sun: Full sun
- Zone 5b frost: Apr 25 â Oct 10
- Season length: ~168 days
- Companions: onion, beets, lettuce
Growing broccoli in zone 5b
Zone 5b has an average last spring frost around Apr 25 and a first fall frost around Oct 10, giving roughly 168 frost-free growing days. That window comfortably fits broccoli's 65-day cycle, with room for a second succession planting if you time it right.
Get a head start by sowing seeds indoors around Mar 21, roughly 5 weeks before your last frost. Move the seedlings outside around Apr 11. Give each plant about 18 inches of space in full sun.
Zone 5b specific growing notes
In zone 5b (Denver CO, Columbus OH), your 168-day growing season means broccoli should be one of your first spring plantings. Cool-season crops thrive in the mild part of your growing window. Monitor soil temperature â broccoli germinates best when soil is 40-75°F.
Your first fall frost around Oct 10 means your last possible harvest is roughly late Oct. For a continuous supply, consider succession planting every 2-3 weeks from Apr 11 through mid-season.
Pro tip for broccoli
Harvest the central head while buds are still tight and dark greenâonce they start to yellow or loosen, you have waited too long. After cutting the main head, side shoots will keep producing smaller florets for 4-6 more weeks.
Troubleshooting broccoli
Imported cabbage worms (velvety green caterpillars) chew leaves to skeletons. Check undersides of leaves daily for eggs. Apply Bt (Bacillus thuringiensis) sprayâit is organic and only affects caterpillars.
Growing broccoli in containers
One plant per 5-gallon container minimum. Broccoli is a heavy feeder with an extensive root systemâuse rich compost and supplement with fish emulsion every 2-3 weeks.
Can you plant broccoli twice a year?
Yesâstart fall broccoli seeds indoors in early to mid-July in zones 5+. Fall crops often outperform spring ones because heads mature in cooling weather rather than warming weather.
Frequently asked questions
When should I plant broccoli in zone 5b?
Transplant around Apr 11. If starting from seed indoors, sow around Mar 21. Because broccoli is a cool-season crop, it tolerates light frost and can go out around Apr 11, before zone 5b's average last frost on Apr 25.
How long does broccoli take to grow in zone 5b?
About 65 days from transplanting to first harvest. A Apr 11 planting in zone 5b is typically ready to pick from around Jun 15. Zone 5b has about 168 frost-free days â plenty of time for a second succession planting.
How far apart should I space broccoli?
Space broccoli about 18 inches apart in full sun. This gives each plant enough room for roots to spread and leaves to catch sunlight without competing.
What is the best tip for growing broccoli?
Harvest the central head while buds are still tight and dark greenâonce they start to yellow or loosen, you have waited too long. After cutting the main head, side shoots will keep producing smaller florets for 4-6 more weeks.
What are common problems with broccoli and how do I fix them?
Imported cabbage worms (velvety green caterpillars) chew leaves to skeletons. Check undersides of leaves daily for eggs. Apply Bt (Bacillus thuringiensis) sprayâit is organic and only affects caterpillars.
Can I grow broccoli in a container?
One plant per 5-gallon container minimum. Broccoli is a heavy feeder with an extensive root systemâuse rich compost and supplement with fish emulsion every 2-3 weeks.
Can I plant a second crop of broccoli for fall harvest?
Yesâstart fall broccoli seeds indoors in early to mid-July in zones 5+. Fall crops often outperform spring ones because heads mature in cooling weather rather than warming weather.
What grows well next to broccoli?
Good companion plants for broccoli are onion, beets, lettuce. Avoid planting near warm-season crops that compete for space and nutrients. Broccoli also benefits from crop rotation â do not plant it in the same spot year after year.