For five years, Colorado State University Extension Master Gardeners in Larimer County have conducted variety trials to determine which tomato and sweet pepper varieties perform best in Northern Colorado’s short growing season.

So far, the project has trialed 12 varieties of in-ground tomatoes, three varieties of container tomatoes and 15 varieties of sweet peppers. As weather conditions vary from season to season, each trial was repeated over two years.

Master Gardeners collected multiple data points from the earliest to produce fruit, the average number of fruits per plant, the weight of fruit and even the flavor profile, which is based on texture and sweetness.

Jon Weiss, the Master Gardener volunteer coordinating the project, is passionate about seeds and gardening.

“We have a short growing season in Larimer County, and that creates challenges for backyard gardeners,” said Weiss, who selected early and mid-season varieties for the trial to best match the region’s climate. “I want to see backyard gardeners have success.”

The in-ground tomato plants in the 2019 trial were damaged by a hailstorm on July 5, with some plant yields more significantly impacted.

“Hail is always a threat, but growing early-maturing varieties may allow the plants to recover and still produce a crop if they suffer damage,” Weiss said. 

Although regional differences and unpredictable weather variables could lead a home gardener to see different results, Weiss believes the basic criteria for selecting better performing varieties applies anywhere in the state. The Larimer County Master Gardeners are not done with trials. Next, they will evaluate cut flowers and winter squash.

Top performers

Looking for fruit early in the season? Ace bell peppers, Hybrid New Girl tomatoes and Hybrid Patio Choice Yellow tomatoes had the earliest maturing fruit. 

Looking for the highest yield? Once again, Hybrid New Girl tomatoes and Hybrid Patio Choice Yellow tomatoes performed well, and Olympus produced the most out of the bell peppers.

“These trials showcase the benefits Colorado State University Extension brings to Larimer County,” said Alison O’Connor, Extension professor of horticulture. “Extension brings the resources of a Tier 1 research university to all of Larimer County.”

In-ground tomato results

Tomatoes were grown in the greenhouse and transplanted on June 5, 2019, and June 10, 2021. In 2019, tomatoes were planted into ground beds covered with black plastic and irrigated with drip irrigation. In 2021, tomatoes were planted into ground beds without black plastic and irrigated via furrow irrigation. Harvesting was done as needed as individual varieties ripened. Yields are a result of the combined harvest from nine plants per variety.