Petri plates are incubated upside - down to lessen the risk of contamination from airborne particles settling on them and to prevent the accumulation of any water condensation that may otherwise disturb or compromise a culture.
why do inoculated plates need to be incubated in the inverted position
to lessen the risk of contamination from airborne particles settling on them to prevent the accumulation of any water condensation that may otherwise disturb or compromise a culture