Perennials that walk the walk

Features - Varieties

From heuchera to hibiscus: horticulture professionals discuss some of their favorite perennial varieties.

October 25, 2017

Veronica, Hibiscus, Coreopsis and Heuchera photos courtesy of Walters Gardens; Echinacea photo courtesy of Saunders Brothers

When it comes to perennials, it seems like growers and consumers are pretty much on the same page. Consumers want plants with low maintenance, a long bloom time and a more compact habit. Growers share these sentiments and take it one step further, searching for plants that don’t require any more labor and costly inputs than necessary.

“We’re looking for plants that are hardy with a long bloom time for multi-season interest,” says Fred Higginbotham, growing operations manager at Millcreek Gardens. “It’s also important that they’re readily available from suppliers, a plus if they don’t require vernalization, don’t need many shearings to bulk up, are somewhat compact and have unique bloom or foliage.”

The flowers that are making their way to the front of the pack this year seem to fit this bill. They’re not necessarily new for 2017, but rather plants that are, by their very nature, proving they have potential to become reliable staples for the industry.

Keeping it compact

Higginbotham shared several of his new favorites in perennials, taking about 100 varieties new to Millcreek this year and narrowing them down to just a handful. For instance, Millcreek has started growing Nepeta × faassenii ‘Purrsian Blue’ as an improvement over perennial bestseller Nepeta ‘Walker’s Low.’

‘Purrsian Blue’ is attractive, in part, because it doesn’t flop as it grows, says Higginbotham. “One of the really interesting things is, as it was finishing in the spring, the stems had this really cool purple color to them, which gave it some added value.”

Higginbotham is also impressed with some fairly new Echinacea varieties on the market. This year, he added Echinacea Butterfly ‘Rainbow Marcella’ to his offerings. “They are very well branched and we didn’t have to use any PGRs on them to get them to bulk up,” he says. They finished quickly and provided great summer color. The multi-colored flowers that attract butterflies should also appeal to consumers.

Heuchera villosa ‘Black Pearl’ may become quite popular with consumers and landscapers with its “really nice big leaves” and deep rich black foliage, Higginbotham says. The plant also holds up well over the summer months, which is an improvement over many other Heuchera varieties.

Another Heuchera that has made its way to Millcreek is Heuchera × hybrida Carnival ‘Watermelon.’ The leaves of this coral bells variety are an interesting mix of colors, displaying peach and green, as well as pink undersides. “Cool nights bring out the nice venation,” Higginbotham says. “That’s one we’re really excited about for next year as well.” It also has a tidy mounding habit and exceptional heat and humidity tolerance.

Coreopsis is at the top of the list when it comes to the attributes of low maintenance, heat tolerance and adding a little sparkle in the landscape. New this year at Millcreek is Coreopsis verticillata Sizzle & Spice ‘Curry Up,’ an upright heavy bloomer. “It’s a great solid plant for some summer color,” he says. “It’s pretty maintenance-free, and you don’t have to do a lot of shearing to bulk it up, which is always a big benefit.”

Veronica ‘Blue Skywalker’ is starting to draw the attention of a lot of growers, including Higginbotham. He says ‘Blue Skywalker’ did well in true 1-gallon pots and stayed mostly disease free. Consumers will like that it is a little shorter than some of its siblings, thus ideal for smaller urban gardens.

Agastache aurantiaca ‘Rosie Posie’
Photo courtesy of Walters Gardens

Critically acclaimed

Many people in the industry are familiar with perennial enthusiast Stephanie Cohen, the “Perennial Diva.” Cohen is an author and speaker at many events and provides a critical eye for the industry. She’ll only recommend plants with a proven track record.

“Through the years it seems that customers want the perfect plant — long season of bloom, no insects or diseases, no critters eat them and no maintenance — there is no such plant,” Cohen says. “However, when I sift through all the new selections that I like, I have grown some that come very close. Some of the most touted don’t make my cut and some of the really great plants just fall through the cracks.”

Cohen adds that trialing can be a tricky business because of the different climatic and soil conditions where the plants will eventually be planted. She suggests growers take their time releasing plants so that a variety with the aggressiveness of “Attila the Hun” doesn’t end up in a garden bed and become problematic, an experience she says she’s all too familiar with.

Here are some plants that made Cohen’s cut:

Hibiscus ‘Mars Madness,’ a native rose mallow, exhibits foliage that looks good from spring right into fall. Cohen says its maple-like leaves are large and impressive. The new growth has a “spectacular” purple growth, while the old growth has a contrasting khaki green color. A large, 6-inch flower is sure to please, and the plant grows to only 4 feet tall. Because it starts flowering a little later in the season, it will continue doing so up until the fall-flowering asters and goldenrods start to bloom. Cohen cautions, however, that it is susceptible to Japanese beetles and shouldn’t be planted near roses.

An outstanding native that is welcome in Cohen’s garden is a variety of anise hyssop, Agastache aurantiaca ‘Rosie Posie.’ It’s easy to grow but does require full sun and ample drainage. Deer will turn up their nose at it, but butterflies and hummingbirds love it. It’s a compact plant that grows to about 2 feet tall and blooms all summer.

Another compact plant that will add interest and texture to a garden is a new salvia Cohen says will rival her beloved ‘Caradonna.’ Salvia x sylvestris ‘Violet Sage’ is a compact salvia variety that begins flowering in late spring. Keep it deadheaded for continued flowering throughout the summer.

Of course, no garden is complete without some grasses. Cohen recommends a couple of hardy Schizachyrium scoparium, also known as little bluestems: ‘Prairie Blues’ and ‘Standing Ovation.’ These tried and tested varieties are shorter and more upright than some of the other bluestems. She says they’re clump-forming and will blend in nicely with mums, asters, sedums and other fall beauties.

Perennial standouts

Another enthusiastic grower, Paul Westervelt, annual and perennial production manager at Saunders Brothers, had no trouble picking plants that he says “walk the walk.”

Echinacea Kismet Intense Orange is everything Westervelt says he looks for in an Echinacea. “It’s visually striking, easy to grow and hardy,” Westervelt says. “From a spring planting, it bulked well before blooming, making it easy to finish a full plant.” He adds that vibrant orange colors rise above the foliage without growing too tall. They fade somewhat with age but do hold their color well. He said the plant overwintered well in several sites in the Northeast as well as in the trial gardens at Colorado State University.

Another plant that stands out to Westervelt is Heuchera Primo ‘Wild Rose.’ Although this one was released at the 2017 California Spring Trials, Saunders had it in its own trials for more than a year prior to its official debut. Westervelt says it has looked “outstanding” every week of the growing season for two straight years. “The vibrant color caught my eye first, but its relatively fast growth rate, great form and year-over-year performance make it outstanding,” he says.

As the trend toward more compact plants continues, Westervelt and his crew say they have been pleasantly surprised with the Phlox paniculata Bambini series. “The hot pink Primadonna and pink and white striped flowers of Candy Crush were the two standouts,” he says. “They were as compact as advertised and we didn’t see a hint of powdery mildew all year in production or our in-ground trials.”

Miscanthus has become a problematic reseeder in some areas so Westervelt was glad to acquire Miscanthus sinensis ‘Scout.’ It’s a Gracillimus lookalike that blooms earlier than its popular doppelgänger and is non-fertile. Slender green blades with white midribs are also a standout.

Last but not least is prairie dock (Silphium terebinthinaceum). “This plant rocks my socks,” Westervelt says. “Prairie dock is native to the grasslands of middle America and is bold and dramatic and wildly underused.” It has huge, raspy leaves that form an impressive clump in early summer and serve as a launching pad for thin flower stems that can reach 6 to 9 feet tall.

So there you have it — several perennials that have proven themselves beyond the trials and hype and hyperbole. Now all you have to do is decide how many to order for the next growing season.

Neil is a horticulturist and freelance copywriter for the green industry, assisting businesses with advertising copy, blog posts, articles, and other digital content.