The Jolly Yellow Giants
Some say that Cup Plant (Silphium perfoliatum), or any perennial that can top 10 feet in height, is unsuitable for a small suburban garden. I disagree.
First of all, Cup Plants add drama to our otherwise flat landscape. Not ominous drama like some noir detective show, but happy drama like a family celebration. Also, I like a flower you can look up to. We can’t have mountains and breathtaking views here in Chicago, but we can have Cup Plant!
Second, Cup Plant is a real magnet for wildlife. The blooms begin around mid-July, but by early August there are Goldfinches gorging on the seeds.
And the flowers themselves attract lots of butterflies, especially the smaller ones, not to mention all kinds of bees.
Some charge Cup Plant with spreading aggressively, mostly by self-sowing. Those messy Goldfinches don’t help in this regard. However, I have not found this plant to be difficult to control. Just yank out the unwanted stems. However, it’s true that if you leave this plant to its own devices, you may have a forest of Cup Plant.
Cup Plant flowers are simple yellow daisies, a bit like small Sunflowers. The common name comes from the fact that the perfoliate leaves join around the stem to form cups that fill with rain water.
Another of the Jolly Yellow Giants is Golden Glow (Rudbeckia laciniata). Above you can see Cup Plant on the left (in the Front Island Bed) and Golden Glow on the right (in the Driveway Border), with a narrow grass path between them. I like how the Mexican Sunflower (Tithonia rotundifolia) makes little orange dots to punctuate all the yellow.
Golden Glow starts blooming a bit later than Cup Plant. The flowers look more sophisticated to my eye, with green cones and soft, droopy rays that are more richly colored. Golden Glow tends to be a bit shorter than Cup Plant.
Here’s a view from the sidewalk. You can see some Sweet Joe Pye Weed (Eutrochium pupureum) over at the far right along with the Bee Balm (Monarda didyma) in the foreground.
Yellow Coneflower (Ratibida pinnata) is tall, about 5 feet, but not really a giant. However it blooms around the same time as these two other giants, and adds another variation on the theme of yellow daisies. The big dark central cone is endearing, it reminds me of a clown’s nose.
All three of these plants attract lots of bees. They also seem to tolerate fairly dry conditions without much stress – at least once they’ve become established. However, both Cup Plant and Golden Glow normally enjoy moist soil.
Incidentally, in my experience Yellow Coneflower responds well to cutting back hard, but Golden Glow not so much.
No, this is not a drawing that the little girl next door did in kindergarten. This is my very own hand-drawn illustration of my method for staking Cup Plants. I’ve tried a variety of approaches, but this one has worked best. Basically, it involves one 10 foot length of rebar as the starting point for overlapping circles of twine. The main idea is that this makes the Cup Plant stems hold each other up. I can’t explain it better than that.
Cup Plants do tend to lean over at alarming angles, and plants flopping over makes me break out in an itchy rash. If you have the same affliction, you might give my approach a try.
There are other very tall plants out there that I’d like to try, if only I had room.
Do you have a favorite jolly giant in the garden, yellow or otherwise? And just how tall does it get?