A number of issues can cause small or stunted rhododendrons, so it’s hard to know what could be causing yours to be small. If you suspect your rhododendrons are drying out too much, try adding a layer of mulch and compost, which will feed and insulate roots. Rhododendrons like partial shade, but too much shade can inhibit growth. They also enjoy a more acidic soil, so try working in some more acidic soil amendments.
A number of issues can cause small or stunted rhododendrons, so it’s hard to know what could be causing yours to be small. If you suspect your rhododendrons are drying out too much, try adding a layer of mulch and compost, which will feed and insulate roots. Rhododendrons like partial shade, but too much shade can inhibit growth. They also enjoy a more acidic soil, so try working in some more acidic soil amendments.