When it comes to the backyard wildlife habitat, the cup plant has it all. To me, it is the flag bearer perennial for bees, butterflies, and birds. It is a stalwart native in 34 states from Louisiana north to Canada crossing every border east. Alas however its size is quite imposing. It is big, bold and wonderful, and this is the time of the year it shines the most.
If you are getting interested but are not familiar with the cup plant, it is known botanically as Silphium perfoliatum and as I alluded above cold hardy from zones 3-9. It can grow tall, 4 to 10 feet, and colonize, so it is a plant for the back of the border. Here at the Coastal Georgia Botanical Gardens ours are around 7 feet.
Though it may be hard to imagine, they can dwarf a brown-eyed Susan, Rudbeckia triloba, or a Brazilan sage, Salvia guaranitica, both also considered large plants and terrific partners for the cup plant. Close by, we have the pagoda flower Clerodendrum paniculatum, Java glory bower, Clerodendrum speciosissimum, as well as Baby Lace, Hydrangea paniculata, all of which do their part to bring in hummingbirds, bees, and butterflies.
You may be asking, why it’s called a cup plant. This is one of the magical attributes of the plant. As the plant grows, it develops large square stems that give the impression of piercing the center of the large leaves. It has two leaves without petioles that are attached to the stem, forming a perfect cup to collect rainwater. Small birds like finches take advantage of this natural reservoir of water. These same birds also feed on the seeds as they mature and get ready to disperse.
You’ll find the blooms to be covered in what may best be described as a pollinating frenzy. Every kind of bee, including honey bees by the hundreds, bumble bees, and wasps are there doing their thing. A quick glance on a recent morning visit showed eastern tiger swallowtails, long-tailed skippers, fiery skippers and yellow sulphur butterflies. It was like a Serengeti for pollinators. Though I didn’t see any, everyone reports hummingbirds on the plants as well.
The nature lover will find this to be one of the most thrilling plants to incorporate in the landscape. Get a chair, a pair of binoculars and a camera, and you are ready for a day of journaling. It will take some attitude adjustment for most gardeners before planting.
First, are you ready to incorporate such a tall, aster-family member into the back of the border? Second, can you accept a colonizing racehorse of a plant so to speak? Not only will you have rhizome spread but you will have reseeding. So, in other words, there will be some maintenance to confine to space allotted.
Native plant nurseries sell the plants, but they are also easy to start from seeds. Sow non-stratified seeds in the fall or stratified seeds in the spring. If you want to stratify, moisten coarse sand and seeds in a plastic bag and store in the refrigerator for three months.
Since this plant will be the backbone of your wildlife habitat or pollinator garden choose companions that are not only beautiful but will bring them in too. I’ve mentioned salvias and brown-eyed Susan’s, but Joe Pye weeds, milkweeds, and ironweeds native to your region would partner well.
Other favorites would be anise hyssops like Blue Fortune, Blue Boa, and Black Adder. They would give that complementary sizzle of opposite colors. Lastly, use the cup plant to create mystery in the garden by blocking a view and forming an area of transition.
The cup plant amazingly does it all for both wildlife and pollinators all the while showing out with dazzling 3 ½-inch yellow blossoms. You have to agree that is pretty doggone special.
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(Norman Winter is director of the Coastal Georgia Botanical Gardens at the Historic Bamboo Farm, University of Georgia Cooperative Extension, and author of “Tough-as-Nails Flowers for the South” and “Captivating Combinations: Color and Style in the Garden.” Follow him at: @CGBGgardenguru
