Rhododendrons and Azaleas - Planting and Care Guide
Rhododendrons are very popular flowering bushes as well as a foundation plant with beautiful, stunning blooms. Rhododendron bushes can grow up to 70 feet tall. They are also closely related to Azaleas however the difference between the rhododendron and an Azalea is that the Rhododendron is an evergreen bush (there are some deciduous) and it is the evergreen varieties that are most popular with home owners. Rhododendrons are larger in height, leaves and blooms compared to Azaleas.
Azaleas are usually classed as a specific group and also are deciduous or evergreen. The deciduous Azaleas can grow to a height of 6ft. The evergreen Azaleas are smaller and grow to a height of 1-2ft and are low spreading.
How to Grow
Rhododendrons are acid loving plants and grow best in dappled shade and need protection from midday sun and winter sun. They prefer a moist, well drained soil with a pH of 5.5 therefore it is important that the pH of the soil is tested before planting and adjusted if needed. Mix in plenty of organic matter or ericaceous compost if needed, and well rotted manure.
Selection of planting site is important as Rhododendrons can be harmed or killed by too much wind and too much direct sunlight. Select a position that has dappled sunlight otherwise the leaves can dry out or burn. A northern site is ideal as the Rhododendron is protected from all elements and will brighten up that dark area of your garden. Planting under a hedgerow is perfect as it will allow for protection of the Rhododendron.
Make sure that water is provided as they prefer a moist soil especially during dry spells. The use of Pine Needles is ideal as a covering as it works as an acidic mulch and helps keep the soil moist as well as keeping the weeds down without harming or disturbing the root system.
Azaleas prefer a sheltered spot in partial (dappled) shade and also need the acid soil as Rhododendrons
If you have a favourite Azalea that needs transplanting, early Autumn is the best time for deciduous and evergreen Azaleas to be transplanted. They can be replanted in early spring, but it must be before the deciduous Azaleas come into leaf
How to Prune
This is always a bit tricky, as pinching back young plants will promote bushy growth. Pruning should be done early in spring, but it may also result in cutting off next year's blooms. If you prune a bush heavily, it may not bloom again for two to three years and therefore it is recommended that you do not prune established plants at all – just let it grow naturally and enjoy the spectacular explosion of its blooms! However if the rhododendron becomes too tall after a number of years, then consider pruning.
Azaleas can be pruned right before the shrub flushes out with the new growth in the spring. Cut the stems cleanly with a sharp lopper or saw and do not fertilise. New growth should sprout in the spring. To keep Azaleas full, prune a portion of the branches to the ground forcing foliage to emerge lower on the plant.
Site selection of rhododendrons is important, as some protection is needed from cold, windy situations and winter sun. There are some varieties that may not tolerate extreme cold so check for hardiness before buying
Insects and Diseases
There are not many insect and disease problems with Rhododendrons, and they should only be treated if needed.