My friend has something very similiar to this on a large tree trunk out side her kitchen window. It really is very sweet...she actually also has a few small windows and door lamp that lights up. I just find the whole thing charming and I am sure a small child would find delightful.
Baking soda neutralizes the ph in the soil and nothing will grow there. use baking soda around all of the edges of flower beds to keep the grass and weeds from growing into beds. Just sprinkle it onto the soil so that it covers it lightly. Do this twice a year - spring and fall.