I heard you're not supposed to plant until after May. Is that true?
If you live in the northernmost part of Arkansas, zone 6, then wait 'til the middle of May. If you live in zone 7 or 8, then you don't have to wait that long.
I agree with
@Becky. At least, in the photo the lighter colors are hard to see. And I like the dark ones!
When you say you want a longer blooming period, do you mean the individual plants keep blooming? Deadhead, and they'll bloom all summer? Or do you mean you want flowers spring, summer, and fall - something is always in bloom? Or a bit of both?
You want perennials, full sun, hardy to zone(s) 6, 7, or 8. What colors do you like? For that matter, what kind of plants do you like? Do you want go native, and have your yard visited by butterflies and hummingbirds?
If you want to find your zone, you can find it here:
http://planthardiness.ars.usda.gov/PHZMWeb/Default.aspx#
Once you've found it, you can enter it in your user profile page (
here)
Welcome to the forum!