ASK THE HORT AGENT
Question Why are holly leaves turning yellow and dropping off?
Answer Hopefully, not all of your holly leaves are dropping. It is natural for evergreen plants to drop some 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 that 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. That means that 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 from one to two years. This means that a live oak drops nearly all its leaves when the new leaves start popping out in the spring.
Plants like camellias, gardenias, 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.
Additional stress will often cause plants to drop more leaves than usual. If the environment is too dry, too wet, too hot, or too 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. All of these stresses affect a plant's roots. 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 greater 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. If your holly is not shooting out new leaves or swelling buds, then you may want to be thinking of a replacement plant. Give it another week or two before digging a grave.
Remember, last summer was too dry. The drought is considered a stress that could cause excessive leaf drop. If you have any further questions, then call me at 910-893-7533 or email me at firstname.lastname@example.org If your plant dies, then call your local priest for Last Rites (which are ironically considered the “seed of eternal life” by Catholics).
Gary L. Pierce
Horticulture Extension Agent