My photinia is close to 18 feet tall and is planted in xeriscape. It has been losing a lot of leaves lately since blooming this spring. Living in NV, our temps get very high in the summer. When do I fertilize, how much water with a drip system and how often to water? How often do you prune and when? The bark on the tree is getting all wrinkled and weathered looking. Do I have a disease in the tree and, if so, what do I do to fix the problem? Thank you for any help.
Red Tip Photinia
Certified GKH Gardening Expert
It is really hard to say exactly how much water you need to give them in order to be watered enough, due to the fact that many factors can influence this. I will say that it does sound like the plant is under watered. This would cause almost all of the symptoms you describe. So increase water to the plant and, as the heat increases, continue to increase the water. As for fertilizer, how often will depend on the product you use for how often you apply it. This should be on the directions on the fertilizer you buy. But, in general, a water soluble fertilizer is applied once every 2-4 weeks and a slow release fertilizer will be every 3 months. Pruning should be done when the plant is dormant (i.e. winter). This article will help: https://www.gardeningknowhow.com/ornamental/shrubs/photinia/pruning-photinia-shrubs.htm