Seeing you are in Melbourne you should never prune till you are sure the last of the frosts have gone, towards the end of September or even later if you are not too sure. And if the weather is tempermental well wait till you see the new leaf buds starting to swell then do it.

Prune off 1/3, bring it back to 2mts every few years you can cut it back even harder if the bush is very old and scraggy.

Do not fertlise after pruning wait at least three weeks or until the new shoots start coming, do it lightly and repeat every four weeks through the growing season whatever fertliser you use just make sure it has a good percentage of Potash for better flowering

Cheers ....MM

We have two large hibiscus trees which have gone all woody as the previous owners never pruned them. Should I prune them right back to encourage new growth or will that kill them?

Thanks

I have what I would call a 'stunted' Hibiscus. It's been the same size (about 2 feet) since we moved in nearly 3 years ago and is growing in rather lousy clay soil. I've never pruned it as the poor thing seemed to small to prune. It seems healthy and flowers well. Will pruning help it also?

Many Thanks

Shame about the clay soil, that would most likely be your problem, Hibiscus need an open sunny position a raised bed would be ideal in your clay as they prefer a well drained, open soil enriched with organic matter, the ph should be 6.2-6.8, fertilise around the drip line and add some sulphate of potash at the recommended rate every four weeks also it will inrich the colour and abundance of the blooms, hope this helps ...Cheers..MM.