Dianne, I strongly urge you NOT to do this.
NOT because the barrel is insufficient for the rose, long-term (it actually IS insuffient, but that's not the problem) . . . but because the barrel itself will fail.

In California, you will find that the barrel will rot out right about the time the rose begins to mature. I know this, because we went through a period when we thought this was a good idea, and we had at least a half-dozen roses so planted.

We were warned.
Kitty Belendez at one time had at least 20 roses in barrels, in Santa Clarita. A few years later, she was writing articles outlining why this is a bad idea.
Did we listen? NOPE. We "barreled" right ahead. :-(

If you really want to do something like this, find a rot-proof container: Plastic. Fiberglass. Ceramic, even. NOT wood.

Jeri

Thanks Jeri. However I had planned on putting a 15gal plastic pot inside the barrel with lots of extra holes drilled in it. Then fill in around it with dirt so the roots could extend out of the pot. But it sounds as if even this method might not be a good idea.

Diane

No. I think that would not be big enough. We grow roses in 15-G squats, with many holes, in the ground, because of gophers. We know when the roses make it out of the squats, because they improve noticeably. I think you won't be happy with what you get.

Jeri

indeed, been there myself, eventually having to dismantle the enormous whiskey barrel piecemeal (not that it was difficult, it practically fell apart). It looked dreadful as well, once the staves of the barrel started to go snaggle-toothed and rotten. Maybe in some deep woodland garden....but absolutely not in a minute urban yard.

Thanks all. Will give up on this plan.

Not quite so minute camanula, just wanting to squeeze in as many roses as possible.

Diane

You can get faux "wine barrels" made out of plastic. Not near so purdy, but they don't rot.

No. They wouldn't rot, but I don't think they're big enough for that rose, other than temporarily. :-(

Jeri

There is something about the look of old wine barrels that also appeals to me. However, when we bought this house there were 2 old ones that were falling apart. So wisdom prevailed and we did not replace them for use in this manner.
We instead use them to house 200 feet of garden hose which is coiled around inside them. My husband drilled a hole near the bottom to pass through the end that goes to the water spigot. This has proven to be a much better use for these rustic beauties. And they are sure easier to use than those plastic thigamajigs they sell to wind away hoses.
We only have one and hopefully can get a second next spring to use down at the barn.
Just another thought.
Jeannie

Jeannie -- I LOVE that idea.

I like it SO much, I am going to suggest it to DH. It's a GREAT way to make use of those barrels, and when the barrel goes bad, you can just replace it.

One thing we have done, when a barrel reached the point of no return, and the rose was going strong, was to remove what's left of the strapping (it always rusts out anyhow) then remove the barrel staves. THEN, you have to get hands UNDER the plant to remove the bottom.

THEN you can use stackable blocks to build a raised bed AROUND the rose.

It's a h*lluva lot of work, but it can be done, and it's better in some cases than transplanting the rose.

Jeri

My experience has been identical to Jeri's with half wine barrels - very bad idea for anything. I still have one daphne odorata growing in a collapsed barrel - luckily the daphne has obviously rooted itself in the dirt - it is large and healthy, after 25 years, although I keep being told they do not live that long! The barrel is literally a horizontal collection of rotted wood - I have planted roses & stuff around it, and my garden is formal nowhere, so it is not a tragedy, but never again.

I have had great luck planting trailing flowers such as petunias, etc, in plastic half barrels or VERY large clay pots in top of huge old tree stumps - they look great, and to my amazement in our climate (I live in SR) the flowers come back every Spring for 3-4 years all by themselves without any action by me. I love old tree stumps!

Jackie

Somewhere, I've seen a huge old tree stump hollowed out enough that flowers were just planted IN it. Petunias, I think. It was really attractive. And there were several brightly-colored glazed pots clustered about it, so the whole thing was very nice.
I think you could maybe plant a Micro-Miniature that way . . . IN a stump.

Jeri

If you are looking for barrels, try a local winery, they often sell them for a good price.

Personally, when I have need for a LARGE pot, I look for a galvanized wash tub with a rust hole or two in the bottom. They too rust out, but it does take more time than a wine barrel