When do you prune photinia and how long and what time does it stay red?
Prune photinia sometime during early spring through early fall. Late spring, early summer being the best time. Unruly plants can be cut back 6 inches to the ground and will come back--annual pruning will help keep them maintained and manageable. Photinia sends out its first flush of bright red leaves in spring and lasts two to four weeks before maturing to green.
I would like to know what kind of fertilizer to use on my Photinias and when is the best time to use it.
Feed it with a balanced fertilizer (8-8-8 would be good) and one that is aimed at acid-loving plants. Fertilize once in spring and once in early fall.
All the large leaves on my photinia are dying. They start turning brown at the bottom of the leaf and continue to the top until the entire leaf is dead. What would cause this?
It is most likely a fungus. Remove and destroy the dead or dying leaves and treat with a fungicide.
Can you propagate from a dying plant (photinia) if the stems have green leaves and it is still a healthy stem?
As long as the stem you are cutting is healthy, you should not have any problems propagating it. Here is an article or two that you may find helpful: https://www.gardeningknowhow.com/ornamental/shrubs/photinia/growing-red-tip-photinia.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/how-to-root-cuttings-from-various-shrubs-bushes-and-trees.htm
We have a thin layer of good soil, but it turns into dense clay.
Few plants can tolerate compacted clay soil; therefore, your best bet is to amend it. Here is an article or two that you may find helpful: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/how-to-improve-clay-soil.htm
https://www.gardeningknowhow.com/ornamental/shrubs/photinia/growing-red-tip-photinia.htm
We have 20 some photinias as a hedge, all about 4 years old and all were doing well until now. One out in the middle is dying (leaves drying up). We have gophers, but I don't think they would do this. Please help with your thoughts on this.
It is likely a fungus. This article will help: https://www.gardeningknowhow.com/ornamental/shrubs/photinia/photinia-leaf-spot.htm
My photinia robusta plants I purchased a month ago are getting brown leaves then defoliating. I am not sure if they will bud again? Advice anybody? Thanks Jock
If they are newly planted, I would say that they are in shock. This article will help:
https://www.gardeningknowhow.com/plant-problems/environmental/learn-how-to-avoid-and-repair-transplant-shock-in-plants.htm
If you can pull them through the shock, they will be fine.