a pic or two will probably get you the best suggestions ... as well as big city location ....

zone only tells us min winter temps on the coldest day .... its otherwise useless ....

ken

What is the actual location of your zone 8b? That designation tells us aboutyour winters but not your summers. How hot does it get? Is it humid? Do you get good rainfall?

In the absence of that information you could look at white cultivars of hardy geraniums.

I live in Tacoma, WA. Very mild climate. Lots of rain in the winter and spring. I recently extended my borders, I don't have pictures of the plants in bloom with the extension. I can look for a few pictures of my current plants in bloom, however I've moved a few plants around.

Here are a few pictures. Again these don't reflect the wider beds I now have. I also took out the dogwood. These photos were taken in late August, so things look a little spent.

I live in the same general vicinity and one plant I like to use as a summer filler for pots or the front of the border is Euphorbia 'Diamond Frost'. It's an annual but will be in bloom continuously throughout the summer and even through a couple of mild frosts.

If you want something a bit more permanent, I'd consider Parahebe lyallii or catarractae or Iberis sempervirens (candytuft). All are low growing, spreading evergreen subshrubs.

sweet alyssum

lambs ears

jasmine

tobacco plant

pansies

purple and white passiflora to train on your wall

blue morning glory to train on the wall

four oclock

sweet peas in white blues and purples to climb up strings attached to your wall

sprinkle cosmos seeds everywhere

for more purples which just glow especially at dusk, and butterflies love them,

there is the dwarf buddleia, nepeta, sage, lavender

There are several white varieties of zinnias, in plants ranging from short to fairly tall, depending on the variety. Zinnias come in essentially every color except blue.