Perennial flowers bloom briefly and abundantly for a short time, from two to six weeks, and remain green the rest of the season. The plant dies back at the end of the growing season, then resumes growth in the spring. In areas with warm winters, some perennials like geraniums and camellias stay green all year. It takes some effort to care for your perennials if you're growing many varieties that have different needs.
Sketch a map of your garden, using pencil and paper, with notations to where the perennials are, their name, color, description and bloom time. When it's time to plant new perennials, you'll know what you have. This will also save you the grief of accidentally digging up a perennial because you forgot it was there.
Compile a notebook with a page for each of your plants. Paste the plant tag or label on the page when you acquire new perennials. Photograph the plant when it's blooming, dormant and has died back at the end of the season, using a digital camera. Note anything you did differently or variations in weather that may affect the perennial's growth.
Move perennials that don't seem to be doing well. Cut them back with shears and replant them. Spring and fall are the best times to do this. If you choose fall, make sure at least six weeks are left before the first frost in the autumn. The moved perennial needs time to grow new roots.
Plant perennials that thrive in your hardiness zone. Roses, for example are difficult to grow in Zone 4 and below because the root system freezes. Others, like peonies, require a chilling period they won't get in zones 8 and higher.
Prune the perennials when necessary, using pruning shears. Some, like clematis and lilacs, bloom better when pruned. Others, like hibiscus, don't require any pruning other than tidying up. Pruning at the wrong time or in the wrong way may mean your perennial won't bloom that season.
Fertilize on a regular basis with the appropriate plant food. Azaleas, hydrangeas and gardenias, for example, prefer acidic soil, so feed them with a plant food made for them. Perennials do better with regular watering. If rainfall is less than an inch a week, supplement the rainfall by watering.
Add fresh compost as a mulch every year in the spring. The organic matter in the soil decomposes and is utilized by the perennials. Refresh the soil every spring with a fresh 3- to 4-inch layer.