Why are my holly leaves turning yellow? ASK THE HORT AGENT
Question Why are my holly leaves turning yellow?
Answer Hopefully, only a few of your holly leaves are dying. Some evergreen plants drop their leaves in the spring. As the new leaves open up, the old leaves make room by dropping off.
Evergreen plants have leaves that stay green all year long. However, that does not mean each leaf lives forever. The life of an individual leaf varies from plant to plant.
For example, Southern magnolias are evergreen. Each leaf lives for 3 years; therefore, one third of the leaves on a Southern magnolia drop off each spring. A live oak is also evergreen. However, it has leaves that only live one or two years. This means a live oak drops nearly all it's leaves when the new leaves start popping out in the spring.
Plants like camellias, hollies, azaleas, and abelias are all evergreen (or at least semi-evergreen). The age of their leaves may vary from 1 to 5 years. However, all these plants will drop some leaves in the spring. The leaves they drop will turn yellow prior to turning loose and floating to the ground.
Not all evergreen plants drop their leaves in the spring. Narrow-leaved evergreens, such as junipers, pines and arborvitae, may shed their oldest leaves or needles in the late summer or early fall. The needles on narrow-leaved evergreens usually last about three years, although some juniper needles may live for 10 years or more.
Additional stress will often cause plants to drop more leaves than usual. If the environment is too dry, wet, hot, or cold, then more leaves will turn yellow and hit the ground. Other stresses like soil compaction, nematodes, diseases, and insects can also trigger additional leaf drop.
Leaf drop (as a result of stress) is a plant's way of saving its own life. Every plant has a certain ratio of leaves to roots (let’s say 1 to 1). All of these stresses damage the roots of a plant. If a plant has root damage, then the ratio of leaves to roots gets high. Plants have to drop leaves in order to regain the correct leaf to shoot ratio. If a plant can not regain its proper leaf to shoot ratio fast enough, then it will probably die.
Leaves loose water, and roots take in water. If water is leaving the plant at a faster rate than it is coming in, then we have a deficit situation. In the plant world, deficit means death. In the political world, deficit simply means election issue (or accountant's manipulation).
Your holly is probably not suffering from anything abnormal. You need to mulch, water, and fertilize properly. Do not over fertilize a stressed plant. It will only make things worse. Give it another week or two before digging a grave.
For more info on leaf drop, visit http://hgic.clemson.edu/factsheets/HGIC2353.htm If you have further questions, call me at 910-893-7533 or email me at gpierce@harnett.org If all the leaves fall off your holly, call your local priest for Last Rites (which are ironically considered the “seed of eternal life” by Catholics).
Gary L. Pierce
Horticulture Extension Agent
Harnett County | 
