Annuals versus Perennials

My husband and I are new to this gardening thing and want to know what the difference is between annuals and perennials. Can you clarify this for us?
Oak Point, Tx. (zone 7b)

I’m glad you asked this question because it is a good one. One way to classify plants is by their life span. An annual completes its life cycle in a year or less, while a perennial will come back year after year. Examples of annuals are zinnias, petunias, marigolds and impatiens. Some common perennials are purple coneflower, aster, and phlox.

Not all perennials thrive everywhere in the country. Regions are divided into winter hardiness zones and heat zones based on the coldest winter temperature and the hottest summer temperature. Whenever you select a perennial for your garden it is important to compare its winter hardiness and heat tolerance to your zone.
Now that I’ve covered the basics of annuals versus perennials there are some other terms that you should know that further define a plant by its life span.

Biennial – This is a plant that completes its life cycle over two years. The first year it produces only foliage and the second year it flowers, fruits and dies. Foxgloves and hollyhocks are both biennials.

Tender Perennial – A tender perennial is especially susceptible to cold weather and should be treated as an annual in most areas of the country. For instance, purple fountain grass is technically a perennial, but it will not survive temperatures below 20 degrees F.

Hardy Volunteer – A hardy volunteer is an annual that reseeds itself in the garden each year making almost like a perennial. Larkspur is a hardy volunteer that I grow in my garden. To encourage hardy volunteers, allow the flowers to die back and form seed heads. Once mature, shake them over the area to be reseeded, or just leave them alone and they’ll fall to the ground. In the spring, identify the seedlings so you don’t pull them up as weeds, and avoid smothering them with a heavy layer of mulch. Also resist using any pre-emergent herbicides in the area.