When to Plant in Broomfield, CO

Broomfield, Colorado features a growing season defined by a median last spring frost date of May 5 and a median first fall frost date of October 1, resulting in approximately 149 frost-free days. This limited window necessitates careful planning and selection of crops that can thrive in this unique timeline, optimizing growth within this specific region.

The microclimate of Broomfield is characterized as continental mountain (cold nights, intense sun), which significantly influences local gardening. Crops such as tomatoes and peppers flourish in the intense sunlight, benefiting from the heat during the day and leveraging the cooler nights to prevent stress. However, cool-weather crops like lettuce and spinach may struggle due to heat stress during the peak of summer.

What to plant now in Broomfield

In early spring (March to early April), plant cool-season crops like peas, spinach, and kale. Start these seeds indoors or direct sow them outside before the last frost on May 5 to ensure a robust harvest.
From mid to late April, begin planting hardy vegetables such as broccoli and cabbage outdoors. These crops can withstand the cooler temperatures as the last frost date approaches to maximize their growth potential.
After the last frost on May 5, it's time to plant warm-season crops like tomatoes, peppers, and cucumbers. These can be sown directly into the garden or transplanted from indoors for optimal growth.
As summer progresses into August, consider planting a second round of cool-season crops. Start sowing crops like beets and carrots that will be ready for harvest before the first fall frost on October 1.

In Broomfield (149 frost-free days, a moderate season), 34 of 56 planner crops fit outright, 21 get two plantings, 1 crop is perennial.

Month by month in Broomfield

Month	What to do
January	While winter holds Broomfield in its grip, now is a great time to plan your spring garden. Research what crops thrive in the continental mountain climate to prepare for sowing.
February	Start sowing seeds indoors for tomatoes, peppers, and eggplants. This is critical because these plants need a longer growing season, taking advantage of the frost-free days after May 5.
March	As temperatures begin to rise, sow cool-season crops like peas and spinach outside. Early March is the ideal time to get these crops in the ground ahead of the last frost.
April	Continue planting cool-season crops and prepare for the warmer planting season ahead. Mid-April is ideal for transplanting hardy vegetables such as broccoli before the frost transition.
May	With the last spring frost on May 5, it's time to plant warm-season crops like tomatoes and peppers. Ensure that soil temperatures are appropriate for their growth.
June	June is the peak growing season with longer days. Maintain your warm crops, ensuring they receive enough water during the hot days typical of the continental mountain climate.
July	Continue harvesting your summer crops like tomatoes and cucumbers. Fertilization and pest management are crucial during this hot month, given the intense sun exposure.
August	As the summer heat continues, consider planting a second crop of cool-season vegetables like beets and carrots. This will allow harvesting before the first frost on October 1.
September	September marks the transition period toward fall. Keep an eye on temperatures, and prepare to harvest any late summer crops before the first fall frost approaches.
October	With the first fall frost on October 1, it’s time to wrap up your gardening activities. Clear out dead plants and prepare your garden for the winter months ahead.
November	This month is focused on cleanup. Start mulching your garden beds to protect the soil during winter. Use this time to plan for next year's planting schedule.
December	Take a break from gardening and prepare for next year's plan. Use this time for research and inventory to ensure you’re ready when spring planting arrives.

Frost dates for Broomfield ZIP codes

ZIP	Last spring frost (50%)	First fall frost (50%)	Zone
80020	May 5	October 1	6a
80021	May 4	October 2	6a
80023	May 5	October 1	6a

FAQ

When is the last frost in Broomfield?

The last frost date in Broomfield is typically May 5, which helps gardeners determine when to safely start planting their crops.

What vegetables grow best in Broomfield?

Vegetables like tomatoes and peppers do exceptionally well in Broomfield due to the continental mountain climate, benefiting from the intense sun and cooler nights.

When should I plant tomatoes in Broomfield?

Tomatoes should be planted after the last frost date of May 5, ideally around mid to late May for the best growth.

Can I garden year-round in Broomfield?

Gardening year-round is challenging due to cold winters and frost dates; however, some indoor gardening or cold frames can extend the season.

How does Plan My Garden help Broomfield gardeners?

Plan My Garden provides tailored advice considering Broomfield's unique climate, helping you plan effectively based on local frost dates and growing conditions.