Growers Chris Williams of K&W Greenery and Brian Karthauser of Karthauser & Sons view flower trial gardens at West Madison Agriculture Research Station. Both serve on the Commercial Growers of Wisconsin Board of Directors. Photo courtesy of John Esser of CGW

by Gail March Yerke

Trial gardens across the country offer a great opportunity for greenhouse growers to see firsthand how plant varieties perform in gardens of their region’s growing conditions. Seed companies and innovative plant breeders have long promoted such trials to introduce and evaluate their newest varieties. University horticulture departments often work with individual companies for their state’s trial garden programs. There is a unique partnership in the Midwest, however, between a university and greenhouse growers that takes place at a research station in Verona, WI, each year.

For the past 20 years, the Commercial Growers of Wisconsin (CGW) has selected varieties of annual flowers to be trialed there at the University of Wisconsin’s West Madison Agricultural Research Station. What’s different about this collaboration is that the greenhouse growers have direct input into what plant varieties are chosen for trials. They also sponsor a field day each year with speakers from the university to explain plant pathology and entomology.

Executive Director John Esser of the commercial grower group explained how the trials are just one facet of the trade association’s function. “We are an educational organization and the trials are just one part of that. We host speakers at our meetings on disease and insect control as well as plant varieties and culture.” The trade group’s meetings typically include a tour of the host member’s greenhouse, networking and hearing the latest news from industry experts.

The Wisconsin growers’ group was founded in 1953, when very little information was provided to greenhouse growers on varieties and culture. While later years saw both home and commercial Extension horticulturists added to many counties in Wisconsin, today there are just a few commercial horticulture agents left in the entire state. In many ways, the group is trying to provide that continuing education for greenhouse growers. “Everybody needs to be kept up to date in what is happening in the industry,” said Esser. “I think that we are providing that education on a non-biased basis for greenhouse growers.”

The group partners with ag research stations from the University of Wisconsin for their flower trials. Located in the south-central part of the state, the West Madison Agricultural Research Station boasts 510 tillable acres with plant breeding trials that feature corn, soybeans, alfalfa, vegetables and flowers. The site also includes 30 acres of certified organic fields. Display gardens are open to the public and the property also hosts industry events along with the university’s own numerous trial gardens. In addition, the research station is used by most disciplines in the Wisconsin College of Agricultural and Life Sciences. Their focuses include agronomic and horticultural plant breeding, community outreach and student training.

Field day attendee John Lewandowski of Milwaukee’s Bluemel’s Garden and Landscape Center commented, “As growers, we’re really familiar with how plants look before they end up in people’s homes. A lot of times things look great in the container but don’t do well in the ground. Seeing how they grow for weeks, months down the line gives us a different perspective. I find these trials very valuable. The whole idea is picking out varieties that your customer will be successful with.”

CGW board member Tom Hartman of Hartman’s Towne and Country Greenhouse in Manitowoc, WI, is one of the driving forces behind the group’s annual flower trials. So how does this university/grower partnership work? He explained that the CGW board meets in autumn to determine what species and varieties of plants are selected for the following year. Plants for this year’s trial are sourced from seven different plant breeders. “This year we got vegetative cuttings from Ball, Danziger, Dumen, Selecta, Syngenta, Vivero and Proven Winners,” said Hartman. “In return, we relay the growing data and they send representatives to tour the gardens as well. I like going to trials that have multiple companies involved.”

In early March, 25 unrooted cuttings of each variety are shipped to Hartman’s greenhouse from the various plant breeders. There, they grow under his watchful eye until they are transferred to the UW Arlington Research Station in mid-April. (Of note, the Proven Winners stock is received already rooted due to licensing.) The rooted cuttings are then transferred to containers for the next six weeks. In late May, they are sent to the West Madison Agricultural Research Station where they are grouped and planted in the field trial gardens. CGW contracts with the University of Wisconsin to plant and care for the gardens throughout the summer growing season.

The 2021 trials featured over 240 varieties from seven different breeder sources and included Lobelia, Angelonia, Scaveola, Coleus, Bidens, Euphorbia and Argyranthemum. Multiple varieties of the same flower can be compared side by side, such as with more than 40 varieties of Lobelia and 48 varieties of Angelonia, one of the largest such trials in the country. Comparison ratings include foliage appearance, uniformity of flowers, flower display (abundance of flowers), weather tolerance, disease and insect resistance, volume/fullness and aesthetics. The flower trial performance results are recorded monthly with a season summary as well. Trial results data are available to the public through the West Madison Agricultural Research Station.

Looking ahead, Hartmann commented on what might be considered for trials in the next few years. “The container garden thing keeps going. People enjoy their flower pots on the patio. With more and more varieties being introduced for that purpose, it would be good to have a container garden trial some time.”

For more information on the flower trial results at the West Madison Agricultural Research Station, visit and