Geraniums can be pruned back hard in spring if they survived the winter and are tall and leggy. Shorten them to about eight inches but leave some foliage. Apply Osmocote around the base of each plant and water it in following the instructions on the fertilizer label. Do not overwater geraniums. Poke your finger into the soil and water only when the top inch of soil is dry. Full sun and warm days are what geraniums crave for flower production but older plants may need to be replaced with fresh young plants after a few years in the ground. If your older geranium does not respond with fresh new growth and flower buds by mid summer yank it out and start with a new plant. Perennials like people do not last forever. Keep growing, Marianne Binetti  P.S. I am assuming you live in a mild climate where geraniums can survive the winter. In cold climate areas geraniums are treated like annuals and replaced each year.