This is the perfect time of year to buy 'power perennials' because they are likely on sale and will still have enough time to establish roots if planted in the ground soon.
Here's a list of blooming perennials that should thrive for years in your garden and are deer-resistant:
Baptisia (False Indigo)
Blazing Star (Liatris)
To see pictures of these plants and to look up planting requirements, click here.
The image above shows Baptisia (False Indigo)