Q.Is there a method to determine the approximate age of a Christmas Cactus? The largest stems are about an inch in diameter.
My hibiscus tree is aged, few flowers and a hard crusted fungus on the branches. I plan to prune it in the spring then spray with what? I would appreciate you help – Audrey Boston
Certified GKH Gardening Expert
Unlike counting rings on a tree, I'm not certain there's any scientific way to determine the age of a Christmas cactus, but if the plant has grown large and the stems are woody, you can bet it's been around a while. It may have been trimmed back in the past, which can trigger more growth than one that's never been pruned. Please read our article about how to take care of an old Christmas Cactus.
https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/woody-christmas-cactus.htm
Certainly, pruning is a good idea for your aging hibiscus. Since there are a number of invaders that like to reside on hibiscus plants, your best bet is to take a piece of branch and leaf to your local nursery to determine what kind of spray it requires.
https://www.gardeningknowhow.com/ornamental/shrubs/rose-of-sharon/rose-of-sharon-problems.htm