The biggest problem with shade gardens are the tree seedlings, woody weeds. Red bud are the worst because their roots go so deep so soon. A six inch seedling can be impossible to pull by hand with roots somewhere down in the Carboniferous. Sugar maple seeds like only a truly mammoth tree can produce are a somewhat different type of problem; they're easy enough to pull but at a density of a couple of dozen per square foot it's a major chore. Same goes for have a couple of dozen red bud trees; pretty and pretty prolific. Hackberry and cherry are concentrated under roost trees where their bird dispersers leave the seeds. When very young hackberry are easy enough, but give them enough of a start and they have a deep root too. The weed wrench only helps when the seedlings are big enough and you don't want them to grow that long. Even the kitchen garden is not immune and the maple seedling weeds are so thick you have to look close to find smaller garden plants. And the squirrels just couldn't get much fatter, and no, more squirrels is not any sort of solution. Between us we've clear cut a forests of trees, just at a seedling stage. Whew!