Perennials that have been hardened off properly can be planted now. If they've been mollycoddled indoors then they won't take it very well and you will have to start exposing them gradually to outdoor conditions. The osteospermum you will have to wait on; they are native to South Africa and are not going to appreciate frost at all. Mind you, if you don't mind hauling the containers in on a regular basis, you could go for it, again, providing they have been hardened off.

Thanks for the help. I am putting the flowers out only during the day and bringing them in at night. I haven't put any in the ground yet. It will be in the low 30's later this week at night so I had thought better to wait.

If they've been staying out all day, you could start leaving them out on warmer nights, IMHO. Mind you, I am terribly impatient when it comes to hardening things off, and on occasion, it has cost me. Anyway, better to wait a bit too long than to jump the gun.