Horticulturist brings patience and perseverance to development of new plant cultivars

The original plant selected in 2012 to be Prunus x cistena ‘UCONNP001’. The cross was made in 2012. In 2016, the final decision was made to introduce and license the plant, and Brand was able to provide hundreds of plants generated via tissue culture to Monrovia Nursery, the licensee.

It takes years of perseverance and patience to bring a new plant cultivar to market. Mark Brand, professor in the Department of Plant Science and Landscape Architecture, has what it takes to plod through this lengthy process. To date, his lab has introduced twenty-seven new cultivars and currently has about a half dozen others in trials, of which he is optimistic several will be licensed in the next year or two.

The first step in launching a new cultivar is choosing a particular species of plant. Some ideas come from grower suggestions, others from a specific need. The latter was the case for Berberis (barberry), a plant that used extensively in commercial landscaping that had become an invasive. Brand developed a sterile version of the plant. Other new plant cultivars come about when an unusual seedling or plant habit is observed, such as a different growth pattern or color, presenting an opportunity to produce something special.

“Occasionally, you find these serendipitous things about a plant,” Brand says. “We originally started working on Buddleia [butterfly bush] because we wanted a sterile version. In Connecticut overwintering Buddleia can be problematic, but in milder climates butterfly bush can be weedy and invasive. With Buddleia, that was our original tactic. But our mutation breeding program produced a dwarf mutant that had a cool form and habit but so-so flower color, so we bred it with other cultivars with strong flower color to get dwarf plants in a range of colors. These plants have been introduced as the Better Homes and Gardens Soda Pop series.” The same mutation breeding program also produced the variegated ‘Summer Skies’ butterfly bush that is part of the Proven Winners® program.

Step two is to grow the parent plants. In the case of hybridization or controlled crosses, the parent plants must be grown to the age where they produce flowers. Pollination is completed in the greenhouse to control the environment as much as possible, so parent plants are usually grown in containers to facilitate moving them around. Brand works mostly with woody shrubs, which need a cold, dormant period. Container plants receive their dormancy-breaking cold treatment in an unheated plastic-covered overwintering hoop house. Then they are brought into a warm greenhouse to grow out and flower. To ensure that the plants flower at the same time, it may be necessary to control the temperature by placing one of the parent plants in a cooler or delaying the time one plant goes from the overwinter house to the greenhouse.

“There’s a lot of tinkering around to get the plants synchronized for cross-pollination,” Brand explains.

Tissue cultured plantlets of the newly licensed dwarf purple-leaf sand cherry Prunus x cistena ‘UCONNPC001’. Brand sometimes uses tissue culture to rapidly build up numbers of new plants for distribution, either for trialing or for growers who then license new material.
Tissue cultured plantlets of the newly licensed dwarf purple-leaf sand cherry Prunus x cistena ‘UCONNPC001’. Brand sometimes uses tissue culture to rapidly build up numbers of new plants for distribution, either for trialing or for growers who then license new material.

It may take two to three years to go from obtaining parent plants to having seed in hand. Once ripe fruits are gathered, the seeds are cleaned from the fruits and the dormant seeds are pre-treated to allow germination. They need about three months of cold, moist stratification, in which the clean seeds are mixed with slightly damp sand, placed in baggies and refrigerated.

Step three requires planting and growing out large populations of seedlings, often several hundred. The initial greenhouse work is done at the floriculture greenhouses. Seedlings that do not meet the selection criterion are culled from the group.

Brand says, “With the Buddleia seedlings, we noticed very early in the process that half were clearly going to be standard height, so we removed those to carry on the dwarf part of the population. With the compact version of the purple leaf sand cherry [Prunus × cistena], one parent is green-leafed and one purple. One quarter to a third turn out to be green-leafed in the seedling stage. You only grow forward the seedlings with good purple foliage color. The first cut helps to control the number of plants.” This culling process is repeated until there are enough young plants with the desired traits.

Step four is moving the plants outdoors in containers or in the field, at the plant research farm. The young plants are grown to quart or one-gallon container size before they are planted in the field. Butterfly bushes might grow from seed in two years, but slower growing plants such as barberry or chokeberry (Aronia) take three years.

Step five is identifying the best plants. Once in the field, the plants are tended and watched. For fast growing plants like Buddleia, Brand was able to make preliminary selections in their first season growing in the field. After that, the Buddleia were left to see how well they overwinter, cut back in early spring, and during the second summer of observation, the team narrowed it down to about twelve or fifteen plants with superior growth and color, out of five or six hundred. This process takes longer with slower growing plants.

Step six involves taking cuttings from these exceptional plants. And then more cuttings. The cuttings are treated with rooting hormone and intermittent mist to encourage growth, and then grown to a quart-sized pot.

The next step is to look for growers to trial the plant variety. The object is to find one or more growers that agree to trial the plant with the goal of licensing the plant and applying for a patent. The patent application must occur within the first year of the first sales.

Young Prunus plants that will go to market.
Young Prunus plants ready for market.

“UConn will not agree to patent a plant unless there is confidence that the plant will generate enough royalty monies to cover the cost of the patent,” Brand points out. In some cases, a minimum royalty agreement is required of licensees to protect the developer, in this case UConn.

A patent application may cost anywhere from five to ten thousand dollars, in a lengthy process requiring extensive data and documentation. When the plants are first sent to a grower for trials, they are not patented, so the growers must sign a material transfer agreement. This requires that a grower does due diligence to evaluate and produce the plant.

Growers will propagate and grow trial plants in containers under their specific production methods, that include container growing and landscape trials. “In most cases we send hundreds of plants to growers to speed up this process,” Brand says.

“In the past, we would send trial plants to several growers for licensing. The marketplace has changed recently, so most larger growers have their own branded product lines and they want exclusive licensing. For instance, our Panicum grass went exclusively to Ball Horticultural. The downside to trialing with a single grower is that in the end they may not choose to license the plant. Then we have to start over with another grower.”

Most growers need two to five seasons to evaluate a plant, which includes multiple winters. But occasionally, a plant will stand out as a winner in a couple of years.

The entire process takes between seven and fifteen years, depending on how quickly the plant grows. Initially, the plant is put to market in small numbers. It takes a while for the commercial growers to develop a larger inventory for wide retail distribution.

“It was a slower process with the barberry, because we had to watch it for a protracted amount of time to make sure it was sterile,” Brand notes. “We watched it in the field for a decade before we went to trials. The grower was able to see our field process and then say they wanted it for production. The Buddleia developed more quickly, totaling about eight or nine years from seed to retail market.”

“If you’re going to work with perennial woody plants, you have to be committed for an extended period, five to ten years minimum,” Brand says. “It takes that long for the process.”

He admits that the long-term duration of working with a plant can wear him down over time. He says, “After ten plus years working on a plant, your interest in that plant begins to wane, because you are now more actively working on new projects. At this point you have force yourself to remain committed because you still need to maintain the plant, collect patent data, take photos, and continually have a plant on hand in case you have to prove that you created it.”

Additionally, if the plant is a success, Brand must write a refereed journal article about the development of the plant and introduction of this new cultivar.

When asked why he continues the search for new plants, he says, “What I find interesting, is making these crosses and waiting to see what comes from them. It’s like opening a present. Sometimes it bombs. Sometimes you get amazing things. It’s also very rewarding when you have a really good plant that makes it to the market, and serves a purpose for growers, landscapers and homeowners.”

Brand has been at the College since 1988 and actively involved in his plant breeding program for the past fifteen years. He relies on his graduate students to assist with the day-to-day work involved in developing new plant cultivars. “It’s virtually essential to have graduate student funding to develop these plants because they are available year-round for several years,” he says. “There is a lot of hands-on work, monitoring and data collection.”

The first group of plants to go to market were not patented, which means there will not be royalties paid to UConn. However, several recently marketed plants are starting to bring royalty monies to the university, with much larger returns yet to come. “Our Aronia Low Scape® Mound and Low Scape® Hedger are Proven Winners®. They had substantial sales this year,” Brand says.

It is likely that the dwarf butterfly bushes and sterile barberries will also generate a significant royalty stream. Royalties are split between the College, the university, and the inventor.

By Kim Colavito Markesich