I hope someone answers you. Mine flopped too, except for the moonshine, which stayed very compact. I tied mine up to get it out of another plant's way. This is the second year for my plants. Last year they stayed much more compact. They are in a raised bed and the soil was amended with compost and peatmoss.

Yarrow flops. I stopped growing it. The only one that stays upright is the old fashioned, tall yellow one (forgot the name) with stiff stems. You can cut it back to the ground after flowering, and it will make some new growth. Next year, put one of those metal plant rings around it before it sends up stems. Or dig it up and throw it out like I did.

The flopping grasses need another year to get sturdy. Mine flopped too, the first year. Again, prop it up. Also, it could be rodents tunneling around the roots in the nice soft soil...like mine do.

The only miscanthus that hasn't flopped for me is giganteus (a/k/a floridulous) which is about 12-14' high.
Suspect the answer to your questions is yes, the rain helped it to flop, the rich soil helped it to flop and some perennials just flop.
Those beautiful perennial borders you see in books, are very carefully staked. However, there are some things that don't flop: echinacea, anise hyssop, most daylilies (but not all), verbena bonarensis..... OTOH, from spring to fall I seem to be going around in circles moving those wire stakes with rings on the top - from iris to campanula, to lilies, to daylilies to asters to...
Cutting back some of the perennials when they are half grown helps by making them branch and become stiffer. i do this to iris, phlox, asters, sedum Autumn Joy.....

Oldroser, you cut back iris? How do you do this and not lose the flowers?? You cut the flower stalk?

Oldroser, when do you cut back your sedums, mine flop when they bloom (the bees still love them - and so do I), but unflopped ones would be even nicer.

The only Iris I have are Siberian, and the deer like them (almost as much as the daylillies (that I used to enjoy circa1990), I can't fence everything.

Philomena,

I'm guessing that you live in Rockland County. Your yard description equals mine ( I'm convinced that little pebbles want to grow up to be rocks or boulders), reality check glacial till - contains many rocks and boulders, reality doesn't matter - they keep growing! Our weather was atrocious, started out nice - got hot and dry (weekly storm) then August (virtually no rain - until last week - then a month's worth in a week, followed by Ernesto's remnants).

Susan, thank you for the tip about older yellow yarrow! I like the older perrennials (so I'm old fashioned (sort of).

Oldroser, I need your guidance/expertise. I have a relatively deer free area(privet hedge + fence) - that supports a perennial garden and some roses. The roses don't do as well as I'd like them to(DW wants to oust the roses(nurtured for her - she likes Tropicanas).I trid.

The perennial garden, the same area as the roses, supports: Aurellian lillies, orange poppies, Liantris, Gailardia, Lavendula, Shasta Daisey's,Cardinal Flower, Monarda(hummers love it).

DW wants to axe the roses, I want to keep them! She loves roses: especilly theTroicana's, what do I do?

hi dadgardens!

No, I'm not in Rockland - I'm a little further north, up in Dutchess county, in Beacon. I'm about 1/2 mile from the base of Mt. Beacon, so there are rocks, rocks, and more rocks everywhere - handy for making borders for flowerbeds !

I have that same question for oldroser, about cutting back sedums and also iris- when and how ?

Philomnea, I took a guess as to your location, your area sounded like my yard - I've cleared areas of rocks, sieves work wonders, but I had them re-appear, I joke about rock re-growth(and their desire to become big rocks); hydrostatic pressure and glacially formed geology keep the rocks moving to the topsoil.

Oldroser - please help us out! When and how do you cut back Irises and Sedums?

Better still, how do I save the roses, that my wife loves? They are now fenced (inside the hedge) and get almost full sun, but the Tropicanas don't like the area, why? Please help me!

The deer can't get at them, they have full sun, but they constantly die (mostly in the August/September) - what I am doing wrong! Pink Perfection seems to thrive, but other species like to give up!

Don

Don, Tropicana is a hybrid tea rose and those are like annuals in this region. If you get a few good years out of them, you're lucky. Prolong their lives by hilling soil up over the top of the crown before frost (about a foot deep). The stems underground will stay green till late spring when you uncover the plant. I've gotten rid of the teas...they always die.

For carefree roses with delicious scent, stick with the old fashioned kind, the grandifloras and the floribundas. David Austin roses are good, too. In catalogs and at the garden centers, look for the ones that say "disease-free" and hardy to zone 4.

Susan

Sorry for the slow response, life interefered.

Do you know of any grandifloras or floribundas similar in color/scent to Tropicana's? They are my wife's favorite, which is why I keep trying to grow them.

If not, I'll follow up on your suggestion about switching varieties (mounding doesn't help all that much - for me).
Don