By far my favorite perennial is the iris. There are so many different types: I have some where the flower is no bigger than a nickel - others have blossoms as tall as my hand from fingertip to wrist! Irises come in every colour of the rainbow, in fact, rainbow is what "iris" means. And the iris is probably the flower that has been cultivated for the longest time of all, going back thousands of years. Some people like the latest hybrids with their extravagent colours and ruffles, but my favorites are the older varieties which I find more elegant in form.

My favorite perennial is Hardy Hibiscus over 5'tall with dinner plate size blooms.

my favorite is angel's fishing rod (dierama) and almost any salvia.

Liatris, Coreopsis, ornamental grasses, daylilies, roses (they count right?) and lilies. I cant pick just one, the others will hear!

Jen

Hostas, lilies, daylilies,ornamental grasses, peonies,heucheras, masterwort.... Oops it was supposed to be just one wasn't it, guess I'm with Jen.

Right now? Ummmmmm..... Arisaema candidissima..... ask me again in 30 seconds!

Perennial geraniums are my favourites. They look great when they are green, when they are in flower, and in the fall when they get their fall colours - the leaves turn that lovely red. I have tons of them - my mother never fails to comment "gee, you really like geraniums hmmm?" when I say I've bought another one.

tess

Platycodon (Balloon Flower), Brunerra Macrophylla (False forget me nots), echinops ritro (globe thistle), Baptisia Australis.

Any of the Hakonechloa grasses, so graceful.
Canna 'Pretoria,' so bright.
Corydalis 'Blackberry Wine'
Euphorbia 'Helena' love the variegation
Variegated liriopes
Tricyrtis hirta, mine has a gold edge, beautiful all year.
Polygonatum 'Red Dragon'
Geranium 'Rozanne'
Dianella tasmanica ?, love variegated and colorful foliage, as you can see from my list
and probably at least 10 more that I've forgotten about for now, oh, oh, such as Hellebores and Autumn Fern, like dirtunderthenails listed.

My favorites:

Perennial geraniums (right on Tess) for their length of bloom, beautiful colors, mounding/weaving forms which tie and anchor a garden together, lovely foliage. I have dozens.
Clematis -- they are nothing more than big vining perennials --most abundant long bloomers in a garden, add height when grown on structures (or structural plants), take a few years to get going but then are anchors of the garden for years
Hellebores -- for their very classy gorgeous late winter early spring flowers, tough constitution, beautiful foliage
Epimediums -- gorgeous delicate flower belies toughness and beautiful foliage, great variety still virtually unknown to most gardeners
Salvias - gorgeous colors and long bloom, both hardy and tender types
Veronicastrums -- the candleabras of the summer garden
Nepetas -- who would not love those long lasting blues
Monardas --anchors of the July garden, so many colors, hummers!
Asters -- premier plants of fall (along with grasses), I love A. oblongifolius because it is a tidy mound and is browse resistant, unlike its brethren
Siberian iris -- so elegant in bloom, so many great varieties
Patrinia scabiosifolia -- what a great airy sulphur yellow.

and on and on....

Other "favorite perennial" and related threads.

Heuchera, perennial geranium (my favorite is "new hampshire"), daylilies, coneflowers, hardy hibiscus, dianthus superbus "rainbow loveliness" (for it's sweet smell)and hosta.
I'm getting ideas from all of you--hope I can get the employee discount again next spring!

How could I forget my beloved very huge Baptisia! Now I'm in trouble...

Jen

Daffodils, daylillies and garden phlox - all passalong plants from my family and my in-laws.

Becky

The Salvias . . . Black & Blue, Snow Hill, Henry Duelberg, etc. etc.