GLENCOE, IL (May 8, 2014) – The robust and showy native perennial Joe-Pye weed (Eutrochium spp.) is often relegated to larger more naturalized landscapes, but certain species can make a fantastic addition to smaller or more formal garden spaces, says Richard Hawke, plant evaluation manager at the Chicago Botanic Garden. Hawke speaks with authority. He’s recently completed an evaluation of 26 varieties of Eutrochium and relatives of the Joe-Pye Weed over a 12-year span.
“Many gardeners dismiss Joe-Pye weeds, but they’re native wildflowers with many great garden qualities,” he said. “It’s true that some varieties are titans and should command the back of the perennial border, but more compact and shorter varieties combine beautifully with other flowering perennials and annuals.”
Joe-Pye weeds produce large, airy flower clusters mid-summer through September, and are valuable for attracting an assortment of butterflies late into the growing season. The domed to flattened inflorescence can span up to 18 inches and grow in a range of colors from purple to lavender to pink and white. Large whorled leaves give the plants a strong architectural aspect, and stems can be especially colorful, ranging from solid red-purple to pink-tinged to purple-spotted. The leaves of sweet-scented Joe-Pye weed (Eutrochium purpureum) are often described as smelling like vanilla.
The comparative trial of Eutrochium and other closely related members of the aster family is part of the Garden’s ongoing Plant Evaluation Program, the scientific study of perennials, annuals, vines, shrubs and trees to identify plants superior for gardens in the Upper Midwest. Plants are grown side-by-side for an easy comparison of ornamental traits and landscape performance. Each taxon in the Joe-Pye weed trial was evaluated for four to six years.
Four of the plants under study received five-star excellent ratings: a white snakeroot (Ageratina altissima ‘Chocolate’), a smaller coastal plain Joe-Pye weed (Eutrochium dubium ‘Little Joe’), andtwo types of hollow-stemmed Joe-Pye weed (E. fistulosum ‘Carin’) and (E. fistulosum f.albidum ‘BarteredBride’).
“The top-rated plants showed strong disease resistance, winter hardiness and robust growing habits, and also produced the most beautiful floral displays,” Hawke said.
Additionally, six taxa received four-star good ratings for their strong performances: two types of mistflower (Conoclinium coelestinum) and (Conoclinium coelestinum ‘Cori’),late boneset (Eupatorium serotinum), coastal plain Joe-Pye weed ‘Baby Joe’ (Eutrochium dubium ‘Baby Joe’),two types of spotted Joe-Pye weed (Eutrochium maculatum ‘Phantom’) and (E. maculatum ‘Purple Bush’), andsweet-scented Joe-Pye weed (Eutrochium purpureum).
‘Chocolate’ has deep purple leaves that fade to green with purple undersides by late season. The variety displayed strong, uniform growing habits, reaching roughly 3-feet in both height and width, and produced prolific white inflorescences. The plant shows excellence resistance to powdery mildew, a susceptibility of Joe-Pye weeds.
‘Little Joe’ has rugose, or wrinkled leaves, purple stems and a heavy show of purple flowers from early August to mid-September. The plant can reach up to 5 feet in height and shows excellent mildew resistance.
‘Carin,’ a tall beauty reaching 85 inches, offers dusky purple stems and a bounty of pink flower clusters, measuring 9 inches across, from early August to early September. The sturdy stems of ‘Bartered Bride’ reach heights of 90 inches and produce white flowers from late July to early Septembers. Excellent disease-resistance contributes to its five-star rating.
Joe-Pye weeds and close relatives are relatively easy to grow, though the plants may need additional water in the hottest periods of summer to avoid wilting. They prefer moist average-to-rich soil in full sun or light shade. Deadheading can help keep plants looking neat after flowering, and also deters seedlings. Larger varieties can be cut back to 2 feet in late spring and early summer, though the practice can reduce the size of flower heads.
“Joe-Pye weeds can be used in formal and informal perennial borders, wildflower gardens and naturalized landscapes,” said Hawke. “They combine beautifully with coneflowers, garden phlox, sunflowers, daylilies and grasses in a variety of garden settings.”
To download the complete study go to chicagobotanic.org/research/plant_evaluation and select Issue 37, “A Comparative Study of Joe-Pye Weeds (Eutrochium spp.) and Their Relatives.”