I haven't grown oleanders in a pot. But when I lived in Boston I had an Italian neighbor that grew several oleanders in pots and overwintered them in her garage.

As for gardenia's, try growing "Kleim's hardy" or "Chuck Hayes." While I haven't grown Kleim's hardy, I do have a couple of Chuck Hayes that do OK in my zone 6 garden. It takes a beating in the harsh winter wind here where I live but it bounces back in spring. A fellow that lives near me grows Chuck Hayes in a more protected area than mine and his seems to fare better.

I'm also a tarheel transplanted in Maryland and I got my gardenia's there. There's nothing like the whiff of a gardenia on a humid Carolina night.

Here is a link that might be useful: Chuck Hayes

Another tarheel missing gardenias-I'm definitely getting some this year. Someone told me that the 'Chuck Hayes' smelled more like a gardenia to her than the 'Kleims Hardy', but it would be easier for me to get the Kleims. I have a couple of weigela, 'Wine & Roses' at the front (eastern exposure, raised bed)that are going to get ousted!

I've never grown oleander but I've been growing gardenias for years. They stay outside Apr-Oct and go inside the rest of the year. They don't look great while they are inside but they bounce back as soon as they go out. I also have a number of jasmines that I treat the same way, though they do better inside over the winter. I don't know what variety my gardenias are, the regular florist variety, I guess. I've had one of them for about 7 years.
Karyn

Aah, the smell of gardenia; I'm going to get some chuck Hayes!

Tarheels, I don't miss the pollen though, do you?

In Durham, I used to have kleims hardy. For some reason, they never really thrived. Could have been the placement -- the garden was mostly filtered shade because of several large pin oaks. I think I'll try chuch hayes here.

Karyn, the jasmine is on my list for inside the house. Maybe i'll put it in the bathroom and the humidity might help.
deepti

I grew oleander for years and wintered them in an unheated porch. The common varieties made it: the dwarf oleanders didn't.

The problem I had was that the oleander grew spindly on the porch so that the branches flopped as soon as they were put outside and exposed to the elements in the spring. I'd cut them way back and then had to wait for flowers.

After a while it didn't seem worth it. I am now cured of my zone denial. My gardenia stays in the yard in the ground. It doesn't look so pretty and there are a lot of burned leaves, but it takes care of itself.

I have two oleanders that stay inside all winter long and stay outside from about April onwards. Oleanders are somewhat cold hardy so I can leave them out as long as it doesn't go too far below freezing.

I have problems with scale in the winter. You really need to watch out for that, it can decimate a plant.

I have my two outside now (have for awhile now) and they are flowering. One had a particular bad case of scale this year so it is still recovering but the other one seems indestructible.

I read somewhere that many people keep them in pots for the summer. The only problem is, in winter, they still need lots of light. Fortunately, I have a sunroom that gets loads of light (and four skylights) so mine survive the winter. Forget about growing them outside, however, I am in zone 7a in NOVA and thought I might try some that were cold hardy to 7b in my micro-climate. They didn't make it. One disappeared entirely and the other grew up from the roots with all new growth. I dug it up and gave it to my MIL who lives in Florida.