I want to plant some wide and short trees/shrub (grows to about 5 feet tall and wide) with large colorful flowers like rhododendron.

However, all the rhodies in my yard have powdery mildrew on them. I don't want to plant a new one that eventually get sick.

What is a good alternative that's low maintenance (including not getting sick easily) and have colorful flowers? The area gets partial sun, perhaps 3 hours per day in the summer, and almost no direct sun in winter.

Just so I don't have to keep asking similar type of question, is there a plant database that I can enter some requirements (e.g. size, amount of sun..) and get a list of recommendations?

zone 8B
WA state (king county)

 

I would recommend that you talk with the master gardener at any quality nursery, this does NOT include just any salesperson at a big box mega-mart homecenter. I personally like Molbak's in Woodinville.

There is also the King County Extension Agent of Washington State University. The office is in Renton and just Googling king county extension service will get you started. Here is their page on gardening. Gardening | King County | Washington State University

 

How have your rhodies been doing in past years with the mildew ? Does it go away on its own ?
Are you sure it is not pollen from trees coating the leafs ?

 

Good point. I'm not sure if they are powdery mildrew or just pollen. Attached some photos, could someone take a look?