Unrestrained kids etc. will trample out anything small except a secure fence. If she gets lots of early morning sunshine with a big shadow coming out from the building in the afternoon then apparently she actually faces east to a large extent rather than true north.

Broadleaf evergreen shrubs are the best overall value. Plant a hardy evergreen bush to furnish and decorate the space and then install a fence or other effective barrier to re-direct foot traffic. It could even be something that is removed later, as long as it is something that won't be knocked or climbing over. Including a sign asking them to go around might be adequate, depending on what the attitude you are dealing with is.