Trial tested: top perennials

Editor's note: In our July issue, Susan Martin wrote about the role of plant trials in plant introductions. She also surveyed trial managers and growers about perennials that have stood out to them over the last few years as must-haves. They also shared which perennials they think more people should be growing in their region. Here's an excerpt of that article. Click here to read the full version.

Q: Tell me about a few perennials that have really impressed you in your trials over the last few years.

Zone 5b: Richard Hawke, Plant evaluation manager and associate scientist, Chicago Botanic Garden

A massive number of perennials are trialed every year at the CBG, but inevitably a few favorites rise to the top. Baptisia Decadence ‘Lemon Meringue’ is one of those standout perennials.

“I love the beautiful bright yellow flowers on dusky stems—it’s an eye-catching combination. We’re growing this variety in our trials and on our green roof, where it has excelled for the past three years. It’s almost as large there as plants in the ground trials.”

Sapphire Indigo clematis is another favorite of Hawke’s because of its “insane flower power.” This non-climbing selection is covered in large, deep purple-blue flowers from June to September in the Chicago trials. Agastache ‘Rosie Posie’ was another star of the 2015 trials, blooming endlessly with bright rosy pink flowers and magenta calyces. Hawke reports that it has survived its first winter in the trial garden.

Zone 6a: Jeremy Windemuller, Trial manager, Walters Gardens; owner of Windridge Perennials and Landscaping

Windemuller has been extremely impressed with Hibiscus ‘Midnight Marvel,’ one of the first hardy selections with dark foliage and a great compact size of 3-4 feet. This plant shines when so many others are struggling from the summer heat, producing large 8-9 inch, red flowers from top to bottom due to its indeterminate bloom habit.

“I have found it very easy to grow perennial hibiscus using bare root plants to produce 2-3 gallon finished plants in just 8-10 weeks with flowers in 12-14 weeks.”

Zone 6b: June Hutson, Supervisor of Demonstration Gardens, Missouri Botanical Garden

Lesser known perennials such as Amsonia ‘Blue Ice’ and Kalimeris incisa ‘Blue Star’ have impressed June Hutson and her team at the Missouri Botanical Garden. ‘Blue Ice’ makes a terrific groundcover as it is one of the only spreading types of Amsonia, and it blooms over a longer period than most. ‘Blue Star’ is a good choice for rain gardens and is long blooming too.

Zone 8a: John Ruter, Professor of horticulture and trial gardens director, University of Georgia-Athens

Ruter is impressed by the vibrant yellow bloom power of Baptisia sphaerocarpa ‘Screamin’ Yellow’ every spring, and likes that it is more compact than many other Baptisias. The new Cannova Cannas have been impressive as well, overwintering well for them in-ground. Setcreasea pallida ‘Blue Sue,’ which is an annual in most zones but a perennial at UGA, is another interesting and versatile plant favored by Ruter.

Click here to read more in our July issue.