When to Plant in Fort Collins, CO

Fort Collins, Colorado, is characterized by a significant gardening calendar defined by the last spring frost date of May 5 and the first fall frost occurring on September 28. With 146 frost-free days on average, the growing season is ample but requires careful planning around early and late frosts to ensure successful gardening. Local gardeners must adapt their planting schedules to accommodate these specific frost dates for optimal crop yields.

The local microclimate of Fort Collins, identified as continental mountain (cold nights, intense sun), offers unique growing conditions. Crops like tomatoes, peppers, and squash thrive in this environment due to the intense sunlight and ample daytime heat, which contribute to strong growth and fruit development. However, crops such as lettuce and broccoli may struggle, particularly in the heat of mid-summer, because they prefer cooler night temperatures and can bolt prematurely.

What to plant now in Fort Collins

Spring: As the frost date of May 5 approaches, consider starting cool-season crops like peas and spinach outdoors in mid-March. These crops can handle the cooler temperatures and will be ready for harvest before the warmer growing season begins.
Summer: After the last frost on May 5, sow warm-season crops such as beans, corn, and tomatoes. Begin planting these in late May to take full advantage of the frost-free days, ensuring they grow steadily through the summer heat.
Fall: With the first fall frost on September 28, it's ideal to plant fall crops like kale and carrots in early September. These vegetables can withstand the cooler temperatures and provide harvests even as the nights grow colder.
Winter: Consider planning and preparing your garden in the winter months. This is when you can gather seeds, plan crop rotations, and research varieties that will do well once the frost dates of spring arrive.

In Fort Collins (146 frost-free days, a moderate season), 37 of 56 planner crops fit outright, 18 get two plantings, 1 crop is perennial.

Month by month in Fort Collins

Month	What to do
January	In January, gardening is largely dormant, but it's a good time to evaluate your previous year's garden successes and failures. Start sketching your garden layout and decide on what crops to grow this season.
February	February is preparing month. Begin organizing seeds and ordering any plants you wish to grow, particularly cool-weather crops like lettuce and peas that you can start planting in March.
March	In March, start sowing seeds for cool-season crops indoors or in a greenhouse. Beginning outdoor planting of peas and spinach is advisable as the last frost on May 5 approaches.
April	April is critical for preparation as warmer days come. Harden off seedlings started indoors and prepare garden beds for planting your cool-weather crops before the last frost date.
May	May signals the lifting of frost concerns after May 5. It’s time to plant warm-season crops such as tomatoes, peppers, and squash outdoors. Be vigilant about nightly temperatures and frosts.
June	June is the apex of growing season; monitor plants closely for water needs due to warmer temperatures. This is prime time for caring for tomatoes, corn, and other summer crops.
July	In July, maintain consistent watering and mulching as temperatures rise. Begin harvesting early summer crops and consider planting a second round of crops that can mature before the first frost.
August	August is the peak season for harvesting summer crops like beans and tomatoes, while also preparing for fall plantings. Start transplants for fall crops like kale for the cooler months.
September	As September rolls in, anticipate cooler nights and prepare for the first fall frost on September 28. Finish harvesting summer crops and plant fall crops to maximize your garden's yield.
October	October often brings the first frost threats; if you have late-maturing crops, consider using row covers or cloches. Start cleaning up your garden and plan for winterizing tasks.
November	In November, review the past growing season. Clean tools and prepare gardening supplies for winter storage. Consider researching crops for the next spring season and plotting your garden layout.
December	December is all about planning. Use this time to research new varieties of plants, gather seed catalogs, and dream about the upcoming growing season as winter holds its grip.

Frost dates for Fort Collins ZIP codes

ZIP	Last spring frost (50%)	First fall frost (50%)	Zone
80525	May 5	September 28	5b
80526	May 5	September 28	5b
80524	May 4	October 1	5b
80521	May 5	September 28	5b
80528	May 4	October 1	5b

FAQ

When is the last frost in Fort Collins?

The last frost in Fort Collins typically occurs around May 5. Gardeners should plan their planting around this date to ensure a successful growing season.

What vegetables grow best in Fort Collins?

Vegetables like tomatoes, peppers, and squash thrive under the intense sun and warmth of Fort Collins' continental mountain climate, making them ideal choices for local gardens.

When should I plant tomatoes in Fort Collins?

Tomatoes should be planted outdoors after the last frost date of May 5, typically around late May, to ensure they grow well in the warmer temperatures.

Can I garden year-round in Fort Collins?

Gardening year-round is challenging in Fort Collins due to its continental mountain climate, but cool-season crops can be grown in early spring and late fall. Indoor gardening or using greenhouses can extend options.

How does Plan My Garden help Fort Collins gardeners?

Plan My Garden provides tailored advice, resources, and tools specifically for Fort Collins gardeners, helping them maximize their growing potential while navigating the unique challenges of a continental mountain microclimate.