I get confused between annuals and perennials.  Which needs planting every year and how long do the blooms last?
Annuals need to be planted every year or "annually", and most die out at the first frost in the fall.  They will however bloom all summer with some maintenance on your behalf - watering, deadheading, feeding.  Perennials on the other hand will return each year, most times bigger that the prior year and/or with a companion plant in some cases.  On average, perennials will bloom two to three weeks (some shorter and some longer) at varying times throughout the season.  Some perennials bloom once while others may bloom multiple times.
 
How often should I divide my perennials?
Different perennials have different needs. Peonies don't require division at all and are only divided when more plants are needed. Daylilies develop a dead spot in the center of the clump with age and should be divided every five to seven years. Some perennials like chrysanthemums and yarrow grow best if divided even more frequently; as often as every two years. Check your favorite book on perennials to find out when each of the perennials in your garden should be divided.

I have ants all over the buds of my peonies. What should I do?
Nothing. The ants are only on the buds to collect sugars excreted by tiny nectaries on the surface of the petals. While they need not be present for the buds to open properly, they won't hurt your peonies either.