Inspect portulaca plants in the morning for spent blooms. Flowers close in late afternoon and overnight, so flowers may appear spent at these times when they are not. All active flowers are open in the morning.
Pinch off the withered blossoms. Remove the blossoms and the top ¼ inch of stem, so that the entire seed producing structure is removed from the plant.
Cut out any dead or damaged stems or leaves completely. Remove these at the base of the plant.
Dispose of or compost the removed flowers and leaves. Old plant matter left in the bed may provide bedding for insects or disease organisms.