Santa Fe landscaping in mid August is the time of year when we are never sure what to cut back. Without cutting anything, many of the perennials and even annuals are likely to flop, or just to fade. How far to go usually depends on preference, and how well you have nursed your plants along the way.
Many containers are now at their full glory. Petunias are now in huge masses. They do need to be dead headed though. Ofter they are so big that it is too much to pinch off each individual seed head, just take off whole stems in areas where there is enough left not to show. The underlayer is going to need the light and the plant needs to put its energy into flowering not creating seeds. Geraniums, marigolds and snap dragons can also use vigorous trimming. Remember, we have three months to go, don’t let the plants out grow themselves too early.