The next time your garden needs a stand-out star, consider tall perennials and be prepared to look skyward, said a University of Illinois Extension horticulture educator.
"Every so often you need a plant that can stand out and make a statement," said Greg Stack. "The plant has to have size so it can be noticed at least half-a-block away."
But when such a need exists, which plant do you select?
"Looking for that tall plant is like looking for a tall center on the basketball team," he said. "The plant has to be well over six feet tall or better and be able to hold its own in the garden.
"There are a number of first-round draft choices to choose from that offer show-stopping color, and stunning performance in an enormous perennial as the focal point of the garden."
All of these full-figured perennials can be considered as a specimen plant, a background feature of the border, a high point in an island bed, or just an eye-catching focal point anywhere in the garden, he added.
Alcea rosea "Nigra" or black hollyhock is a plant six to eight feet in height. It prefers moist, well-drained soils in a sun location. During June and July it produces dark, chocolate-red flowers that are three to four inches in diameter. Even though hollyhock is biennial, once established there are always some showy blooms every year. They are also great for the old-fashioned garden.
"Also in the large category are two Eupatorium or Joe-Pye-Weed," said Stack. "'Gateway' and 'Selection' easily grow to six to eight feet in height and are almost five feet wide. Because of their size, give them room and understand one plant will cover a lot of space.
"Both varieties produce flat-top cluster of mauve to lavender flower. They bloom from late August to September and prefer a moist, sunny site. In addition to their size, they are excellent butterfly plants, making them a must stop for all kinds of butterflies late in the season."
Ligularia stenocephala "The Rocket" or Golden Ray is an imposing specimen for the moist, shady garden. Big, bold, heart-shaped leaves one foot across are the first thing one notices. During July and August, tall spikes of yellow daisy-like flowers are produced.
"One thing to note is that these plants will wilt during the heat of a very hot day," Stack said. "They will, however, quickly recover as cooler temperatures return at the end of the day."
Rudbeckia are popular perennial garden selections and when it comes to big, there are two to consider.
"Rudbeckia maxima, the Great Rudbeckia, grows to six to seven feet tall. It prefers a sunny location in a well-drained soil," he said. "In addition to producing large, daisy-like yellow flowers on tall stems, the foliage is also noteworthy. Most of the foliage is clustered toward the base of the plant and is a stunning silver-blue all season.
"The other tall rudbeckia, Rudbeckia nitida 'Herbstone,' tops out at seven to eight feet. Flowers are yellow and bloom in July and August. Foliage is green and not as striking as with maxima."
For something that is both tall but often called a "see-through plant," Stack suggests Thalictrum rochebrunianum or Meadow Rue. At five to six feet tall, this perennial has an open, wiry habit. Purple flowers are produced in May and June. Because of this open, wiry habit it can be used with other shorter perennials, allowing them to be seen through the stems of the Thalictrum. This perennial prefers a sun-to-light-shade site in moist, rich soil.
"As with all plants, be sure you have ample space to accommodate any of these perennials so that they can give 110 percent in the garden," said Stack.
