It would very much depend on which Hibiscus you have Eric.....

Meanie's right - the only one that's reliably hardy outside are cultivars of Hibiscus syriacus, which makes a large, woody shrub or small tree eventually. They require a sheltered, sunny situation, preferably southfacing with a wall or fence behind them. If the soil is light, incorporate some humus rich material before planting (garden compost, leafmould, well rotted manure, etc.) Plant in Spring, not now.

I have a Rose of Sharon - Hibiscus Syriacus and find mine disappointing as the leaves appear very late in spring and the blooms do not show until later in summer. Pretty blue when it does flower but there are much better freer flowering shrubs. I wonder Ericb if yours came to nothing because the leaves are so late? what time of year was it when you decided yours were dead?

Drc, Rose of Sharon is Hypericum, not Hibiscus, leastways, it is usually. Is that a common name round your way for Hibiscus too?

Sorry Bamboo but it is Rose of Sharon - Hibiscus Syriacus. Rose of Sharon is a common name nationally that applies to several different species of flowering plants. Hypericum calycinum is another one called Rose of Sharon and I also have that too.

Never heard it applied to Hibiscus before - that's more commonly known as Rose Mallow. Just goes to show that the common names are, in fact, even more useless than I originally thought, if that's possible...

I only learnt it when I bought the shrub a few years ago now. until then like you I thought it was just for Hypericum, and yes 'rose mallow, shrubby mallow' is another name for it.

We've always known Hibiscus syriacus as Rose of Sharon, here in the States. Hypericum is known as Aaron's Beard, here. Bamboo's probably right in them needing extra heat in the UK, though! If I were planting one there, I would put it on the south side of a wall (or boulders), about a meter from the wall--to keep it from pushing the wall over, later.