When to Plant Brussels Sprouts in Colorado (2026 Guide)
When considering when to plant Brussels sprouts in Colorado, understanding your zone's specific frost dates is crucial. For instance, in Zone 5b, the median last spring frost is May 5, while Zone 5a experiences this frost later on May 17. These dates significantly affect when you should start your seedlings indoors and when to transplant them outdoors for a successful harvest.
Brussels sprouts are a unique crop that thrives in cooler weather, and their flavor improves after exposure to frost. With a growing season of 80 to 110 days, you'll want to plan ahead. In Colorado, those in Zone 6a, where the last frost is April 25, can expect a longer growing season of about 174 days, making it ideal for this vegetable.
For those living in areas like Colorado Springs or Aurora, timing your planting is essential. Beginning your indoor planting in early May can yield a bountiful harvest in autumn as these hearty vegetables will be ready just after the first frosts up to October 1. By understanding the frost dates and following some key care tips, you'll be well on your way to enjoying delicious homegrown Brussels sprouts.
Planting Schedule by USDA Zone in Colorado
| Zone | Indoor start | Transplant out | Direct sow | Harvest |
|---|---|---|---|---|
| Zone 5b | Start May 18 – May 31, ~6–8 weeks before July 10 | Transplant outdoors June 1 – June 15 | Direct sow June 1 – June 15 | Harvest starting October 1, after light frosts |
| Zone 5a | Start May 18 – June 1, ~6–8 weeks before July 10 | Transplant outdoors June 16 – July 1 | Direct sow June 16 – July 1 | Harvest starting September 27, after initial frosts |
| Zone 6a | Start April 10 – April 24, ~6–8 weeks before June 1 | Transplant outdoors May 1 – May 15 | Direct sow May 1 – May 15 | Harvest starting October 16, after light frosts |
Brussels Sprouts Planting Windows in Colorado
- Indoor start: Start Brussels sprouts indoors from May 18 to June 1 for consistent growth.
- Transplant outdoors: You can transplant your seedlings outdoors from June 1 to June 15 for optimal results.
- Harvest: Expect to start harvesting your Brussels sprouts around October 1, once light frosts begin to sweeten them.
Common Mistakes Growing Brussels Sprouts in Colorado
- Many gardeners in Colorado mistakenly plant Brussels sprouts too late in the season, missing the chance for a successful autumn harvest. Since they require ample time to mature, be aware of your local frost dates and plan accordingly.
- Failing to provide ongoing fertilization is another error Colorado gardeners often encounter. Brussels sprouts need consistent nutrients throughout the growing season, especially as they push for larger sprouts closer to the frost.
- Overlooking the effects of late spring snowstorms is a mistake some Colorado growers make. Late frosts can stunt Brussels sprout development, so take action by protecting your young plants with covers or cloches as needed.
- Neglecting to remove lower yellowing leaves can lead to airflow issues, increasing the risk of disease. Colorado's sometimes high humidity can exacerbate this problem, so keep plants clean and well-trimmed for better health.
- Many first-time gardeners assume that Brussels sprouts can be sown directly in the soil without prior indoor cultivation. In Colorado, the growing season is short, and starting seedlings indoors gives you a much better chance for good yields.
Frequently Asked Questions
What if I'm in a cold pocket of Colorado?
If you're in a colder area, consider starting your Brussels sprouts indoors even earlier and using row covers for protection after transplanting. Choosing a variety suited for shorter seasons can also help ensure a successful crop.
Can I still plant Brussels sprouts in May?
Yes, but the timing depends on your zone. If you're in Zone 5a or 5b, you may need to start indoors in late May and transplant in early June to ensure a successful crop before the first frosts.
How long until I can harvest?
Brussels sprouts typically take around 80 to 110 days from transplanting to harvest. In Colorado, depending on your zone, this could mean harvests starting from late September to mid-October, especially after a few frosts.
What if my plants are struggling?
If your Brussels sprouts appear stunted, check for issues with soil fertility or moisture levels. They may need more nitrogen early on, and ensuring good drainage during heavy rains is crucial to avoid root rot.
Should I remove lower yellowing leaves?
Yes, progressively remove yellowing leaves as they appear. This practice helps to improve airflow around the developing sprouts and reduces disease pressure, which can be crucial in Colorado's variable climate.
Keep Learning
City guides in Colorado
Other crops in Colorado
Typical fall sowing window for Brussels Sprouts in Colorado: July 27 – July 27.