WARNING! DO NOT DO THIS! ASPHALT ROOFING SHINGLES
ARE TREATED WITH HERBICIDES AND FUNGICIDES! Also,
particulates, many of them poisonous, collect on
roofs during dry spells. Here in Southern California,
we have had fatal incidents of poisoning by collected
rainwater runoff from roofs. Trying to use shingles
as garden mulch is not a good idea to say the least.