Things You'll Need
Alcohol or another disinfectant
Gardenias (Gardenia jasminoides) are excellent specimen or accent plants with glossy evergreen foliage and waxy, white flowers. During early summer, the sweet fragrance of the blooms drifts throughout the garden. A gardenia grows up to 6 feet wide and tall, depending on the variety, and usually does not require extensive pruning unless it has grown too large for the area where it is located. General pruning should be done in early spring before the new growth begins; this will avoid interfering with the development of the flowers. Removal of damaged, diseased or dead branches can be done any time of the year. Gardenias grow in U.S. Department of Agriculture plant hardiness zones 7b through 10.
Check for crossed, broken, diseased or dead branches that need to be removed. Assess the size and shape of the gardenia to determine where it needs to be cut back and how much should be removed. If the shrub is overgrown, decide if it needs to be severely cut back to rejuvenate it.
Remove limbs and branches that show signs of disease, such as fungal growth, cankers, or wilted and dead leaves. Cut limbs and branches on a slight slant about 1/4 inch above a bud that faces in the direction you want the new growth to grow. After removing diseased plant material, clean the pruners with alcohol or 1 part bleach to 9 parts water to prevent the spread of disease to healthy plant material.
Cut back limbs and branches that are crossed and rubbing another branch, as well as those that are spilt, cracked or damaged.
Trim long limbs and branches that affect the shape of the gardenia. Remove weak, thin or drooping limbs, or shorten them so the other branches hide them.
Thin out dense growth by removing older branches close to the trunk of the shrub.
Rejuvenate overgrown or straggly-looking gardenias by cutting all of the branches and stems back to 12 inches long. When the new growth is 6 to 12 inches long, trim the tips to encourage the growth of side stems so the plant will be fuller.
Use bypass hand pruners for small stems and limbs, and anvil pruners for larger branches that measure 1/2 to 1 inch in diameter or for dead branches. Use loppers for branches that are more than 1 inch in diameter.
Gardenias may freeze back to the ground if the temperature drops to 0 degrees Fahrenheit. When new growth sprouts from the roots in the spring, cut out all of the dead branches.