ideally, outside the 'drip line' which allows you to have access to the house when you need it (like to paint, or wash windows)

though part of it depends on your soil, part of it depends on your foundation, and part of it on your gutter/eaves set up.

I have hostas and corydalis living in the 'hell strip' under our eaves, and haven't had a water retention problem- but I also don't water them, the seem to live just fine on what splashes on to them from the walkway.