Rhododendrum questions

Is it in ericaceous compost? I am asking as they only thrive in acid soil. I also know that some years they have a rest... mine used to, anyway!

Clay soils tend to be acidic so Rhododendrons should be quite at home in it . Id be tempted to take it out of pot and plant it out.

I also have a large rhododendron that is having a rest this year. It's flowered every May. However, my wife dead-headed the flowers quite brutally last year ... perhaps this is a facor.

Rhododendrons and azaleas need a fair amount of light after they bloom to stimulate them to produce flower buds for the next year. If kept in the shade, they seldom bloom or bloom poorly.

To much nitrogen from fertilizing too much will stimulate vegetative growth but prevent flower bud production. Liquid fertilizers are not good. They us chemical nitrogen which kills microorganisms in the soil which rhododendrons need to absorb nutrients. They need very little fertilizer, but a powdered fertilizer with organic fertilizer such as cottonseed meal is ideal. I would only fertilize once each year in the spring after they bloom.

Since they start producing flower buds several weeks after they bloom, any pruning must be done immediately after they finish blooming or you will be removing flower buds for the following year.

If the leaves are yellow with green veins, the plant is chlorotic and the soil may not be acidic enough and/or may be deficient in iron, phosphorus, and/or magnesium.

If there are flower buds but they don't open, that may be caused by drought or very cold weather.