Perennial plants, those that live for more than one growing season, typically have short bloom periods. They may last a week or two, perhaps up to a month. The trick is to have a variety of plants in the perennial flower bed so that something is blooming all season long.
Here are three plants native to Wisconsin that are similar in looks and in soil and light requirements that will provide bloom from June through September. Although all three plants have “weed” in their common names, these plants are anything but weeds. Like most native plants, they need little care once established and are important in the ecological web, providing food for many insects and birds.
The first to bloom, in June and July, is swamp milkweed, Asclepias incarnata. It prefers full sun and moist soils, although it doesn’t necessarily need to be in a “swamp.” Low wet areas, bog gardens or rain gardens are ideal, but any sunny spot will do if spring and early summer rainfall is sufficient.
Swamp milkweed grows three to five feet tall and stems are topped with vibrant pale rose to rose-purple flowers in flat clusters. The flowers are pretty from a distance, but viewed close-up are absolutely amazing. Lance-shaped leaves climb the stems.
You probably know that monarch butterflies lay eggs only on milkweed species. Swamp milkweed attracts twenty other species of butterflies as well, including the pipevine swallowtail and Baltimore checkerspot. Bees and wasps arrive to pollinate the flowers and American goldfinches eat the seeds.
Next to bloom, from July through August, is Joe-Pye weed, Eupatorium purpureum. Depending on soil conditions and the weather, plants grow from three to seven feet tall. Flowers are dusty rose, not as brilliant as those of swamp milkweed, befitting their mid-summer bloom season when days are bright and hot and a bit of cooler color is welcome. Joe-Pye weed blooms are more mounded in profile than those of swamp milkweed. Leaves whorl around stems which are often deep purple in color. It does fine in drier conditions and can take some light shade. Many butterflies visit Joe-Pye weed for nectar, and goldfinches, towhees, mourning doves and juncos eat the seeds.
The final bloomer is ironweed, Vernonia fasciculata, whose flowers provide an electric magenta finale to the bloom season. Blooming from late July into September, the flowers are in flat, dense clusters atop stems from two to six feet tall. Leaves are coarsely toothed and lance-shaped.
Ironweed prefers partial sun and moist conditions but will also grow in full sun and mostly shade. Ironweed hosts many late summer butterflies including the great spangled fritillary, monarch and tiger swallowtail. Bees visit ironweed for pollen and nectar and the plant hosts the ironweed borer moth whose larvae are eaten by small mammals and woodpeckers. The common name of the plant comes from its tough stems.
All three plants can be propagated by division in spring or fall.