Wow! What an interesting list. I never thought about counting the days. My bleeding heart never lasts that long although sometimes it reblooms. I think our heat and humidity in the South makes for shorter bloom times...and the heavy rains that we occasionally get knocks off many blooms. One plant that I have that stays in bloom for a long time IF the deer do not eat it is Trillium cuneatum. It usually starts in February, and there are still a few showing now, although most have gone down. I will pay more attention this season. "How do I love thee? Let me count the ways"...er, days. Anyway, thanks for sharing.

WOW!! Great idea. I'm a novice perennial gardener, this is my third year. I've got some of the same plants, and some not on your list. I tend toward deer-resistant gardening! I'm going to count the bloom days this summer, and get back to you! I'm near Vancouver WA, but up in the Cascade foothills.

Ncrescue, thanks for letting me know about Trillium cuneatum. Now that I know it blooms a long time, I've put it at the top of my list of Trilliums to look for. As for the bleeding heart, mine are in a lot of sun, which is probably a factor in their blooming a long time for me. I find they do well in full sun, as long as their soil isn't too dry.

Agretz, welcome to perennial gardening! My method for keeping track of bloom times is a spreadsheet. For each type of plant I grow, I record the day it starts blooming and the day it stops. In another column, I subtract the first date from the second, and that gives me days of bloom. The spreadsheet can also be used to average the bloom time over multiple years. This system works really well for me. Having the spreadsheet to fill out means I pay more attention to my plants.

This list is very, very helpful. Thank you!

Is spiderwort (tradescantia) native? Once it starts blooming (it started last week in Michigan) it doesn't stop until a hard freeze.

Oxeye sunflower, Heliopsis helianthoides, is another -- big, bushy, full of yellow flowers for a couple of months or more.

These are plants that seem to bloom for a long time but I am not sure they are native though they do grow wild.
White violets bloom then stop them bloom again. Helleborus bloom for a long time. Spring beauty are still blooming although past their peak and they started in Mar. Ground ivy blooms continually if it is not shaded out. Fleabanes both common and daisy bloom a long time although the common starts blooming first. I think all of these flowers bloom at least 2 months which seems like a long time to me. This is an interesting list

Spiderwort (Tradescantia) is native. Hellebores and ground ivy aren't, although the latter has escaped and spread so much you'd think it is.

One of my favorite long-blooming natives is prairie or downy phlox, Phlox pilosa. Here in middle TN it begins blooming in late April or early May and quits sometime in July, depending on rainfall. It's fragrant, too. And unlike so many long-blooming plants, it lives more than a couple of years.

Another fave is Aster (now Symphiotrichon) oblongifolius 'Raydon's Favorite'. In my garden this cultivar begins blooming in September and keeps going until mowed down by a hard freeze, which is often late Nov.