Thanks for using Ask an Expert. Moss generally grows on compacted (hard surfaces), overly moist surfaces (soil with poor drainage), and shady areas (under trees, north side of trees, under shade-loving plants). You need to take care of the situations that cause the moss to flourish and the best way is to remove or improve those conditions. Compacted areas in flower beds can be aerated by piercing the soil with a spading fork. Check the amount of water you are putting on the beds and the drainage situation that exists. You can improve drainage by amending the soil with organics, utilizing drain lines, or planting in raised mounds. Make certain that leaves, especially oak and other acidic leaves, are not left in the flower beds; overly acidic soils favor moss. You can scrape the paved areas and check for drainage or low spots that aren't draining properly. Chemical treatments must be used with caution: always read the labels and follow instructions carefully. Many moss killers stain concrete and wood surlaces if improperly used. It is difficult to use chemicals in the flower gardens because of potential harm to desirable plants. Good luck treating this problem and keep in mind summer is coming when moss is less lilkely to grow aggressively.