When is it best to prune them? Why do geraniums in Europe have 80% flowers and 20% leaves, and here in Midwest Australia it is the other way around?
I think the flowers and flowering vary with the cultivators that are grown.
Also Geraniums that are grown from seed vs plugs vary quite a bit.
You can prune your Geraniums back really when even it is necessary.
Here are some links to help you.