pruning magnolias

Magnolias don't respond well to pruning unless they are young as they don't heal over well. It's best to prune only what is necessary in summer right after bloom.

I once read that you shouldn't prune magnolias unless really necessary, as once pruned, they send out straight 'water shoots', and you have to keep on pruning them. Don't know about whether this is true or not, as my magnolias are small & I haven't pruned them!