In Defense of Cup Plant

Just recently I read an informative post entitled “3 Problematic Plants in Native Plant Gardens and 3 Native Alternatives”. The post was on the Facebook page of Indigenous Landscapes, a native plant landscaping company based in Cincinnati. While the arguments made in the post were reasonable, I had a somewhat different take on the plants in question.

New England Aster
New England Aster

First, the authors recommend Aromatic Aster (Symphiotrichum oblongifolium) as a substitute for New England Aster (S. novae-angliae). Aromatic Aster, they argue, has a much neater and tidier habit than its New England cousin.

Certainly it is true that the straight species New England Aster can be very tall, gangly and bare-kneed. Even after being cut back, I find that it needs staking. One way to deal with this, of course, is to put it behind shorter plants.

Aromatic Aster, Symphyotrichum oblongifolius, Anise Scented Goldenrod, Solidago odora
Aromatic Aster with Anise Scented Goldenrod.

In my experience Aromatic Aster is rather short-lived in soil that is rich and moist, where it can also get just a bit gangly and floppy, though not nearly to the same extent as New England Aster. Under these conditions, I would go with Short’s Aster (S. shortii), which has a shrubby, upright habit and abundant blue flowers. Short’s Aster will also tolerate a fair amount of shade.

One problem with Short’s Aster, though, is that it is hard to find – the only place I know of where it is available is Prairie Moon Nursery.

2014-09-28 15.42.20 Short's Aster
Short’s Aster

The authors also recommend Prairie Dock (Silphium terebinthinaceum) as a substitute for Cup Plant (S. perfoliatum). Both these plants are extraordinarily tall. They argue that Prairie Dock is less likely to flop and self-sows less aggressively than Cup Plant. What’s more, Prairie Dock has big striking leaves at the base and tall, almost leafless stems that give the upper part of the plant a transparent quality.

DSC_0460 cup plant and wild bergamot
Cup Plant with Wild Bergamot to lower left

This is a valid argument to an extent, but I would argue that if Cup Plant is too big for someone’s garden, the odds are decent that Prairie Dock is as well. To be honest, to my eye Prairie Dock has an almost skeletal look which is not always appealing.

prairie dock
Prairie Dock. Photo from Prairie Nursery.

In our garden, I have not found Cup Plant terribly difficult to control, though it certainly can self-sow. And it can require staking to keep it upright, but that’s something I’m willing to live with in exchange for its many virtues – particularly the bold leaves that create small pools of rainwater, of great value to wildlife, where they clasp the stout stems. 

Cup Plant does nicely placed behind plants that are tall but not towering. In our garden we have it growing behind New England Aster.

Early sunflower prairie sun
Early Sunflower

If the Silphiums are too overpowering for a smaller garden, an alternative to consider is Early (or Ox Eye) Sunflower (Heliopsis helianthoides), a bushy plant that only grows 3-6 feet tall.

bluestem goldenrod
Bluestem Goldenrod

Finally, the folks from Indigenous Landscapes recommend Showy Goldenrod (Solidago speciosa) as a replacement for Canada Goldenrod (S. canadensis). Not that anyone ever plants Canada Goldenrod, but it will sometimes crash the garden party on its own.

anise scented goldenrod
Anise-Scented Goldenrod

I have no quarrel with this suggestion, but I would mention two others that are shorter have more shade tolerance: Bluestem Goldenrod (S. caesia) and Anise Scented Goldenrod (S. odora). Of these, Bluestem Goldenrod has flowers spread along arching stems, Anise Scented Goldenrod is more upright.

Would you plant Cup Plant in your garden? What about Prairie Dock or New England Aster?

56 Comments on “In Defense of Cup Plant”

  1. I have New England Aster, but it is in the back of the garden, so I see its lovely blooms but not its naked stems. I plan to plant cup plant in the southwest corner of my yard, downwind, so the seeds will be the neighbors’ problem – although since they just have treated lawn, I don’t expect to see any volunteers over there. Any golden rod that shows up in my yard is welcome.

  2. I do have cup plants in the garden and love them! They do spread out a bit but I don’t find them to be particularly aggressive…in fact, I’m trying to get them to take over a spot behind our shed which is rather bare so I grabbed several seed heads last fall and scattered them in that area. Hopefully, they will do their thing in that spot. And, in my opinion, it’s far more aesthetically pleasing than Prairie Dock.

  3. I commented, and saw several other comments, about cup plant on his post. It has been growing in my rain garden for five years and has never flopped. The pollinators love it. I have a native plant nursery in northeast Indiana and sell cup plant, compass plant, smooth blue Aster and both showy and blue-stemmed goldenrod for gardens and landscapes. I decided not to offer prairie dock, New England Aster and, of course, Canada goldenrod!

  4. I don’t have Cup Plant or Prairie Dock. I have been a bit shy of planting them due to having Jerusalem Artichoke and hating the way it is so invasive. I have been trying to get rid of it for 20 years. I love the look and the wildlife benefits of it but it is so unruly. It runs through, over and around every plant near it. The best asters in my garden have been the ones that have just shown up. I don’t think any are the New England Aster. One is white. The other is a blue but I just don’t remember where it came from.

  5. I’ve grown and grow Cup Plant for years and never had it flop. I like it a lot. Last year I had a volunteer Prairie Dock that reached about 10 ft. tall. It was a conversation piece. I like the basal leaves even though they are so rough. I am thinking of keeping it from getting skeletal. Thanks for your alternatives. Canada Goldenrod will take over your neighborhood.

  6. Absolutely no prairie dock! Yes, dock plants are pretty, and the individual flowers are pretty, but there’s that in between part! Possibly 9′ of in between. I like cup plant. It’s one of the “100 Plants to Feed the Bees” (book from the Xerces Society). It grows tall, but not 9′. Plus, it has leaves up and down the stem!

    I tried New England asters once, they all died. Probably my fault though. If we’re talking about planting for pollinators, the same book recommends smooth blue aster, New England aster, western silver aster, New York aster, and arrow-leaved aster for the East and Midwest.

    I’m growing Canadian goldenrod! A compact one, Baby Gold.

  7. I’ve got every intention of adding some Cup Plants to our hillside this year- and Prairie Dock would look hideous by comparison so I’ll stick with Cup Plant! I’ll also go to bat for New England Asters as I’m convinced no other Aster would look as good as it does where I have it planted. Of course it needs facer plants (but that’s not unique), but i love the height and drama it brings and suggestions of shorter Asters leave me asking, whats the point? The again, I’m constantly thinking many of the plant selections available are just too short- perhaps that’s the problem not having any trees in your garden!

  8. I write for the indigenous landscapes page. Don’t take it personal, the reality is MANY gardeners don’t have the skill to properly design with cup plant, New England aster, and Canadian goldenrod. I never denied their ecological value, this post was just to help Gardners prevent the horticultural messes they can easily get into with those less garden friendly plants. Poor looking native plant gardens give native plants negative publicity specifically to people who don’t understand what they are looking at. Prairie dock, aromatic aster, and showy goldenrod or simply easier for the average person to understand and design with than their mentioned counter parts and many people appreciated this guidance. I’m going to copy and paste a comment I provide when people wonder why I believe native plant gardens must be aesthetically correct to be effective for conservation. It lies in the fact that their footprint is so tiny, their main value is in creating awareness and new advocacy for conservation. Even if every lawn in the u.s. was turned into native plants, let alone gardens, their footprint would compromise just 2% of the land. This is why their main value is cultural enguagement, and for it to be culturally effective it must look good. There are many gardeners who can’t so easily make those plants look good, so consider that post for them if not for you.

    • Hi Solomon. Don’t worry, I’m not taking it personally. My response was mainly about how there are other good native alternatives than the ones you mention. The ones you mention are mostly fine, though I would not recommend Prairie Dock to the kind of gardener you talk about in your comment. Anyhow, best of luck to you in promoting native plants, whichever they are.

  9. You’ve written about the virtues of cup plant before. I’ve admired those photos online and just have to make the leap to plant my own.
    I have New England aster and they do look great in late summer, but I do have to cut them back severely or they’d take over that garden patch. I also have Short’s aster (from Shooting Star in Georgetown, KY before they went out of business). Short’s aster is very pleasing.

  10. I’ve always enjoyed seeing your cup plant in bloom and reading of your admiration for it. Every gardener should have one or a dozen plants they’re willing to go to bat for to defend. The Prairie Dock photo doesn’t make it seem very appealing.

  11. Wow, you lost me on this one. In regard to your last two questions about three plants, I would grow any one of them that I happen to like as long as it not invasive. What is invasive in your regions may not be invasive here. I have never been one to take recommendations from others who know less about what I want in my garden than I do. There are a few things, like you native black elderberry or goldenrod, that I would not be likely to grow, just because I believe (but do not know for certain) that they can be invasive, and potentially naturalize.

  12. If anyone has a deer problem, I recommend they try Cup Plant and NE Aster! The deer do chomp on them early in the season, but tend to leave them alone after summer appears. This free “trimming” doesn’t hurt the plants and the blooms grow at about 4 feet and later in the season.

  13. I would love to plant all of these in my garden, but I have too much shade for the Silphiums and too many rabbits for the Asters and Goldenrods. I love to see all of them in the wild, however. I think all have places in various types of gardens–depending on the conditions and the spaces. Wonderful plants!

  14. Here in our small corner lot in SE Nebraska, 1 or 2 cup plants, 1 or 2 prairie docks, several New England asters, and a number of kinds of goldenrod grow and do fine. I do cut some of them back a bit when they are about half grown so they will be less lanky. I also have a number of other kinds of asters, some cultivars, but can’t remember what kind. I am thankful to live in our neighborhood, where people walking by compliment the yard, and we have never had complaints. We are blessed to have lots of pollinator visitors to the blooms and caterpillars find the plants they need to thrive on. Oh, and I have some Jerusalem artichokes in a raised bed across the street, where the neighbors allow me to garden.

  15. Heartily endorse your recommendations of blue-stem and sweet goldenrod (whose foliage is much smoother than most Solidago, tolerates more shade, and smells like anise when bruised).

    I’m a big fan of aromatic asters, which among other virtues extend bloom at the late end, but agree that if your soil is rich and moist, you’ll be happier with New England varieties. Both kinds self-sow here (western Va, clay soil), and some of the New Eng. progeny have larger and more vivid blooms than the parents (deep purple ‘Treasurer’ & magenta ‘September Ruby’).

    In all except the worst drought years, both N.E. and aromatic asters, as well as phlox, benefit from being cut back at least once — around Memorial Day, and most seasons again near the 4th of July. Beats staking, which I just won’t do, and keeps them upright while increasing (and delaying) bloom.

    Haven’t experienced deer “helping” with the aster cutback; they’re too busy chowing down on lily and daylily buds.

    Does anyone reading grow Silphium mohrii? I’m always attracted to anything with pale/light yellow flowers, so have put it on my second-tier wishlist, but have no actual garden reports.

  16. This was an interesting read. There may be gardeners who attempt cup plant here, but it’s not native; we have other Silphium species, but not that one, and I’ve never seen it. I was interested to read about the Canada goldenrod, too. Down here, that’s a common name for Solidago altissima — also very tall, and often found in great masses in the countryside.

  17. Great suggestions, Jason. I think it’s all a matter of personal preference and what space you have in your garden. I haven’t had any luck yet in getting cup plant to grow here, but I agree it’s much prettier than the prairie dock. I do have both New England Aster and the Aromatic aster, however. I cut back the New Englands in the spring so they aren’t so floppy, and I really enjoy them. The aromatic asters are a little tidier. As for goldenrod, I’ve never planted any, but have plenty of volunteers every fall!

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