Vireya Tropical Rhododendron
I have a Vireya Rhododendron Tropical Glow in a container plant in a semi shaded area and is about 1 m high. I would like to know when is the best time to prune back the plant and how, so it can continue to bloom. Also, I sometimes notice some of the green leaves partially go brown. How can I remedy this?
Vireya rhododendrons are generally very rewarding plants to grow, producing large numbers of brightly coloured flowers. However, they do have a tendency to become quite long and leggy. Vireyas really benefit from a good hard prune, just as long as you know what you are doing.
If you start when the plant is young, and pinch out the growing tips of branches, you will encourage the growth of more branches further down the plant. This will result in a bushier plant and more flowers in the long run, although it will probably delay the first flowers.
If however, your plant is a little older, and has already become straggly, then remedial action is required. Pruning can be done at any time of the year in warmer parts of the country, but avoid pruning in cold conditions. Some growers recommend late spring and early summer after flowering has finished. Prune to just above a healthy whorl of leaves at the desired height. If extensive pruning is required, you may want to do it over a longer period of time rather than all at once, to allow the plant to recover. After flowering, remove spent flowers and seed pods.
Healthy and happy plants tend to be bushier — so make sure your vireya is in well-drained soil with lots of bark or other fibrous material. Vireyas prefer semi-shaded conditions, but the more light they have, the bushier they will be.
As for the leaves going brown, this could be due to erratic watering (either too much or not enough), poor drainage (vireyas do not like to sit in clay and much prefer very free-draining mixes with lots of bark), or possibly a fungal disease such as powdery mildew or an attack by thrips. I suggest you start by looking at the medium your plant is in and your watering regime. Then check the leaves for signs of a fungus, or of insect damage (which might include silvering or bronzing). If either of these are the case, then spray with an appropriate fungicide/insectide.