Yes it's Silphium perfoliatum. I wouldnt move it now. It will overtake the zebra grass, but the zebra grass will help keep the Cup Plant somewhat under controll. I wish I had planted prairie grasses around my Cup Plant, but I didn't and it grew as big as an army tank. Cup Plants will seed everywhere. I have a small garden, so I deadhead my Silphiums now. I grow Cup Plant, Compass Plant, Prairie Dock and Cut Leaved Prairie Dock. I pulled out my Rosinweed a week ago because all it's leaves were turning brown for the past 2 years. I like to watch insects and birds drink from the cups.

Wait, the cup plant will overtake the ZEBRA GRASS!?!? DH had to take a pickaxe to the other clumps of ZG to get them out, this is the last remaining clump of that grouping. IDK how anything could overtake it.

When should I move it?

My rosinweed is doing great. I only have one clump, but she's a stellar performer. I wonder why yours had been turning brown. I'm having the same problem with culver's root -- they look terrible after blooming. I can't bear to take them out because the pollinators absolutely adore them, and I get such joy from looking out the window at the buzzers feasting (they're right outside my window).

In a small garden you can manage cup plant by cutting it to the ground after it flowers. Never let the plant set seed!

Nice pics, Jay. The compass plant leaves look so good in your pic, makes me wish I would have bought one yesterday, they had them at the nursery but they looked kinda ratty in the pots so I passed.

I had a cup plant a few years ago and re-located it to the meadow. Never saw it again. Same with some helianthus divisions I moved back there. Go figure {shrug}.

My pasture-turned-meadow out back is at least 1/2 acre, maybe a little more. We keep the rest of the 3 acres mowed. If I didn't have fruit trees back there I'd let the area where the fruit is do it's thing and revert to meadow. Not much is blooming now back there, DH did a cut in mid-June to take down the grasses (I still don't know what the crop is - maybe oats or rye, or both, whatever the horses pooped out, I guess), which of course sets back blooming. Still, last year I had more in bloom at this time so IDK what's going on. After the cut, a nice clump of stiff goldenrod disappeared, which surprised me - goldenrods are pretty tough. Eh, she'll poke her head back up next year. I think maybe next year I'll have DH cut back at the beginning of June to see what happens. The only reason he cuts back once early in the season is because the crop (whatever it is) will get over 6-foot tall if he doesn't, and we don't want that.

So porkchop, the tall Silphium flower stalks always exceed 6 ft? Is that permissable for you? They don't really obstruct the view. You and your husband are probably partially megalophobic like me, and feel threatened by overly large plants. I also experienced that disorder with Angelica atropurpurea in the past.

I once killed a stiff goldenrod with a root prune and a chelsea chop. I was shocked, because it had been a vigorous monster. I killed 2 Early Goldenrod plants and 1 Cliff Goldenrod plant this spring when I cut them all the way back to the ground. I'm theorizing the plants put so much energy into their foliar growth, that the roots were depleted of energy reserves. Pity, because I was emotionally attached to my Cliff Goldenrod, S. drumondii.😪 I guess the moral of the story is 'don't overdo it wirh your chelcea chops, when it comes to goldenrods, no matter how deranged you are' Lol. I have quite a few species, so if there is any species you need in a broadcasting quantity, Im happy to share with you. I will have tons of Rattlesnake Master seeds. They add interesting color and texture. Do you grow Lead Plant? Goat's Rue, Tephrosia is a beautiful legume subshrub. Lead Plant is woody.

Laceyvail, Im happy to hear you deadhead your Silphiums, very smart. I wish I could leave the seeds for the goldfinches, but those coniving goldfinches never eat them all because they are conspiring to mass propagate them in my little garden. The seedlings grow deep roots very quickly, requiring the use of a trowl. I chopped my Cup Plant all the way to the ground, at least 3 times last year, and it still bore flowers at less than a foot tall.

https://www.facebook.com/share/r/19aG3iMFZD/

Actually, I left that Silphium at my old garden because it was too much to tend to at my age, but I did bring a start of a Silphium gracile that is always well behaved.

"You and your husband are probably partially megalophobic like me, and feel threatened by overly large plants."

Oh heavens no -- I love big-*ss plants!

Here's what was out of frame in the post above:

Yes, I know the Joe Pye covers part of the window and many people think that's a no-no, but I planned it that way -- the house sits higher than the surrounding ground, and on the other side of the window is the long view from the kitchen across the great room to the outside = I have something to look at out the window, particularly enjoyable when the birds start nibbling on the seeds.

Here's my native hibiscus, over 5-foot tall:

You can see I have more big-*ss plants off in the distance. LOL!

"I'm theorizing the plants put so much energy into their foliar growth, that the roots were depleted of energy reserves."

That's interesting, and makes sense. I'll see what mine does next spring - if it comes back I'll tell DH to cut closely around it and not take it down (I'll have to mark it with a flag or something, he pays no attention to this sort of thing). Thanks for the offer of the goldenrods, I'll keep it in mind.

"Never let the plant set seed!"

I'll have to keep that in mind, also. :0)

“Yes, I know the Joe Pye covers part of the window and many people think that's a no-no, but I planned it that way”

I do this as well, porkchop. I deliberately planted a tall monarda in front of my great room windows so that I could enjoy the view of the flowers and the pollinators when I’m inside. As far as I’m concerned, my garden doesn’t have to please anyone but me.

I took a walk around the pasture and what did I see? Another cup plant! It was only about hip-height which is why I didn't see it from the house, probably due to the mow-down the pasture got in mid-June. Anyway, was happy to have another volunteer. It's kinda fun to go back there every so often to see what's popped up -- although it's also sometimes disappointing not to see stuff I know I planted, but then again my outlook on that area is the plants have to duke it out for themselves, it's survival of the fittest.