An easy way is the deadheading of rhododendron bush on a regular basis. You can remove the old seeds and flowers from top of the bushes and they will continue to grow naturally in a shape. Also, it will give more space to growth of new branches and flowers to blossom. On the other hand, it will also help you to keep your garden clean and tidy.
Checking Shape Regularly
While doing deadheading regularly, you can also check for the shape of rhododendron bushes, and if you feel they are some branches that are getting crowded, you can cut them from the stem. Also, pluck or remove old leaves or buds so that they do not force the bush out of the shape. If you think certain branches are growing into different direction, you can cut them out to let the plant grow in the shape you want.
If you do not check the bushes for regular shape and prune them, you will need drastic trimming after they have blossomed.It is likely that they have got themselves crowded with other plants in the garden. You will need to clear them thoroughly to create more space for branches for their future growth, as a crowded bush can grow wild and all over the place.
Do not move all the branches from the bushes so that they are not able to grow again. This will destroy the beauty of your garden while damaging the bushes altogether. To avoid over-cutting the bushes, regular pruning is the best solution for shaping them. Regular pruning can also help you to plan the shape of the bush alongside its growth.