The right time to water is when the flowers start to bloom. It is important that the entire root ball remains moist. In spring, the top layer is often a bit drier, and as summer nears the root ball could dry out fairly quickly. Ensure enough watering in the run-up to summer to make sure that the root ball is sufficiently watered. Try to keep the moisture level even. Otherwise, this could result in root rot (Phytoftora).
All Rhododendrons need nourishment, in particular during the growth season from April to September. The best option would be an organic fertiliser; not in excessive quantities, but regular doses. The smaller varieties will need less. In the event of prolonged rain, the dosage can be increased. Artificial fertiliser is also an option; read the instructions on the packaging and be careful in respect of quantity and frequency.
Mulching is important because of the plant’s shallow roots. Mulching is the application of a layer of organic material on the soil above the root ball. This could be peat or finely-cut tree bark. The maximum thickness of this layer should not exceed 5 cm. Mulching has a protective function. It makes the plant weed-resistant and prevents the loss of moisture.
Although the plant generally requires no pruning, it could be a good and necessary thing to do for various reasons. After blooming, the flower stems should be removed to preserve the shape. Another option is to prune back to the last-blossomed ring of leaves. Removing the end buds is also an option, as it will force the plant to produce more runners. You could also apply crude pruning to large plants if they are verging on too lage. This needs to be done in two stages. For example, you could prune the left half this year and the right half next year. It is important to mulch after pruning and to reduce the application of fertiliser. After crude pruning, it could take a while before the flowers return, up to a few years, so you have to be patient.
