Aglaonema Pictum Tricolor should be pruned by gently cutting off any yellowing or brown leaves at the base of the stem using sharp, clean pruning shears. It is important not to remove more than one-third of the total vegetation at a time, as this can cause stress to the plant and hinder its growth. Pruning should be done in the spring or early summer when the plant is actively growing, as this is when new growth is most likely to occur. After pruning, the plant should be fertilized and watered regularly to encourage healthy growth.