Annuals vs. Perennials: What’s the Difference, Anyway?

Annuals complete their life cycle in one year, which means they flower and die in a single growing season. They usually bloom from spring until frost. Some annuals, such as violas, sweet alyssum and pansies, drop seeds that produce baby plants again next spring without any help from you.

Perennials, such as irises and peonies, come back year after year if they have the right conditions. Just make sure the plant is suited to your USDA Hardiness zone (check yours here). The foliage also may die back any time from mid-summer to early winter, with new growth appearing from the same root system next spring. A “tender perennial” means a plant that acts like an annual in cold climates but a perennial in warm climates.

Annuals have showy blooms all season long, while perennials generally have less flashy flowers for a period of two to eight weeks (which may appear in the beginning, middle or end of the growing season). Perennials, such as hellebores and bleeding hearts, also offer late winter or early spring color when it still would be too cold for annuals. So, you absolutely need a mix of both types to round out your garden!

No matter what type of plant you choose, follow the plant tag or description for sun requirements. For example, full sun means six or more hours of direct sunlight, while part sun is about half that. Full shade means no direct sunlight. There’s no way to fudge this: Plants that need full sun, such as marigolds and geraniums, won’t perform or bloom reliably in shade, and shade lovers will sizzle in hot sun.

Annuals, such as calibrachoa and impatiens, can go in the ground or pots at any time, even during the heat of summer when your garden needs some sprucing up (just keep them watered!). Perennials should be planted in either spring or fall, as long as it’s no later than six weeks before the first frost in your area. Check with your university coop extension service to find out the estimated date here.

Perennials such as asters, daylilies and irises often do better if you divide them every 3 to 5 years. You can tell it’s time because they seem crowded, less healthy or stop blooming. Simply break off a piece along the edge with your garden spade, and replant at the same depth elsewhere in your garden. Now you’ve got more free plants! It’s fine to divide in spring or fall, but try not to do it when the plant is blooming so its energy can go to root and leaf growth.

Annuals give it their all in one season, but perennials, such as clematis and columbine, take a few years to really get going. Don’t give up on them the first year or two. A common saying is “crawl, walk, run” when it comes to perennials, because they really don’t start to take off until their third season in the ground. But hang in there; we promise they’re worth the wait!