On this site I've flaunted some of the Southern plants that Northerners are unable to grow, but the tables can be turned. Lilacs are one of the plants that I envy. They absolutely will not grow where I live, but smell wonderful and are easy up north. Here's a picture of a lilac in my mother-in-law's yard. (Also note the nice redbud in the background. We
can grow redbuds down here!)
There are several shrubs/trees that we can use as possible substitutes for lilacs. I have seen crape myrtles touted as the Southern lilac. They start blooming in June and put on a spectacle for the next month or so. Here's a picture of mine. I don't know which variety this is, but it looks nice growing in my front yard. As much as I love crape myrtles though, they don't seem like a lilac sub to me because they have no smell, which is one of the most notable traits of lilacs.
Buddleias, which are better known as butterfly bushes, can also be something of a substitute for lilacs. They have similar-looking panicles of flowers which smell very sweet. This is the only picture I have of my Royal Red buddleia. These fellows are great here in the South. They are a must have for attracting butterflies. There are many colors to choose from. They are also easy and grow just about anywhere in the United States. In the South, they get big enough to be small trees. Deadhead the blooms when they fade and you get a second flush.
There is one other candidate for a lilac substitute down here, and that would be the vitex or chaste tree. I just got one of these late last year and have no pictures yet. You can look it up on Floridata or Google to see what it looks like. It's another old favorite that is not seen often anymore. Vitex comes in colors blue, purple, and white. Blue is its best color. It has a nice fragrance, gets to be a small tree about the size of a crape myrtle, and will also rebloom if deadheaded. I would import some pictures of it, but I'm worried about copyright infringement. Just trust me, vitex is a
very worthy Southern plant. It's said to be hardy to zone 7. One other great thing about the vitex is that it's very drought tolerant. Check it out and try it. By the way, if anyone reading this has a picture of their vitex tree, I'd love to get a copy to post.
PS - Thanks to another blogger for sending me this picture of a vitex tree to include. Check out his web page at www.phillipoliver.net.
Red Double Knockout rose. Blooming as prolifically as ever.
The little China rose Ducher with some plumbago behind it. This rose loves our Louisiana heat.
Julia Child rose. Healthy and cute!
Gertrude Jekyll. Much more repeat bloom this year than last.
Pink crape myrtle. Just beginning the summer flush of bloom.
Westerland rose. Orange and fragrant.
Belinda's Dream. What a wonderful rose variety!
Telstar Picotee dianthus, still blooming into the heat of summer. I sheared them back a few weeks ago hoping to keep them going till next fall.
Rose penta. This plant seems to get better as the weather gets more miserable. It loves heat and humidity.
Incense passiflora. Such a unique bloom.
Luna Swirl hardy hibiscus. 
Thunbergia alate - Black-eyed Susan vine. 
