Q.Rhododendrons
Some of the leaves of our rhododendron are going brown in the centre. We have been having an extremely hot summer with very little rain. I gave our shrubs a good soaking about three days ago and am wondering if this shrub is suffering from lack of water. There is a good covering of bark chips over all of the garden plot.

Certified GKH Gardening Expert
This could be the issue, but if you overwater, then this could be the issue as well.. It never hurts to put wettable sulfur into the soil as well as dolomitic lime. This will correct the pH and re-condition the soil, as well as kill off anything that may be lurking around in it.
This article will give you more information on the care of these: https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/rhododendron-care.htm

Thank you for your advice, Bush Doctor, and for the website link.