RHododendron 'Catawb Grandiflorum'

Jmairlot68

My rhodendron is in its third season and is in a large pot. The first year it flowered, the second year it had only one bloom and this year it has buds but they are not opening. Also the leaves are looking pale and are drooping. I have replaced the compost (ericaceous) and fed it with seaweed and sequestrine but it is definitely not happy. I think the buds may have been affected by the late snow but am not sure how to treat the plant to help it survive.