The squirrels are much better at burying and germinating black walnuts than I am, so when mowing I watch for the fresh seedlings coming up, then transplant them to where I want them. Of course, those I found last night were sprouting in the gravel soil by the road -- so, I made several Onewheel trips with shovel and bucket to transplant them to the avenue. And then, watering the seedlings and young trees by dribbling irrigation from a tank of pond water, I time it by Onewheel passes up and back on the quarter mile of grass.