A perennial is a plant that lives for more than two years. The term is often used to differetiate a plant from shorter lived annuals and biennials. Perennials grow and bloom over the spring and summer and then die back every autumn and winter, returning in the spring from their root-stock rather than seeding themselves as an annual does. A great way to expand the color in your garden!
Successful perennial gardens start with thorough and thoughtful bed prep and planning. Key points include: choosing a sun or shade plant, eliminating perennial weeds before turning the soil; insuring a well drained soil yet having it retain moisture for plant growth; providing for sufficient organic matter; and adding needed fertilizer.
Most of these plants come in 3" pots unless they state that they are bare root divisions.