Rhododendrons add lasting beauty to gardens. There are hundreds of species, from 80 feet trees to rockery dwarfs, of every color except clear blue.
Where is the best place to plant a rhododendron?
In Australia rhododendrons reach the height of their splendor in Tasmania and Victoria and in the cooler districts in other States. They are not recommended for growing north of Toowoomba, Queensland.
In most locations it will be found that shade from the midday sun and protection from strong cold southerlies and westerlies are advisable.
Rhododendrons thrive in natural conditions where the soil is acid. They are lime-haters.
Soils should be cool with plenty of humus or leaf mold and should be loosened to a depth of 3 feet before planting.
Avoid cold, heavy clay soils, lime, ashes, and most artificial manures, also areas that get very dry in the summer.
Some of the roots of rhododendrons are small and fibrous, and feed close to the surface. Don’t disturb these by hoeing and digging, but give food and protection by mulching in summer with well-rotted cow manure, leaf mold, or other cool humus.
How to care for rhododendron
Move established plants in autumn or spring. New plants obtained from nurseries should have a good ball of soil all round.
Dig holes big enough to take the ball and drop in so that the top of the soil is level with the surrounding ground. Don’t tramp or tread heavily all round; merely firm the soil enough to keep the plants from wobbling; then water well.
Mulch the surface with 2 inches or more of peat-moss or leaf mold to prevent drying out and heating of the ground. The mulch feeds the roots as it ages, and should not be dug in or disturbed.
In very cold and frosty districts double or treble the depth of the mulch in early June.
Flowering periods vary according to the species, but most flower from about May to early December. When the flower clusters die break them off with your fingers, removing only the dead wood or any tops that appear to be diseased.
What to spray on rhododendrons for bugs?
The rhododendron family is allergic to attack by various insect pests. Lace bugs should be sprayed repeatedly with Malathion or D.D.T. emulsion, which also kills thrips. Red spider mites should be sprayed with Malathion.
How to prune rhododendrons
Pruning rhododendrons is tricky.
If the shrubs indicate that they require cutting back by throwing out tall, lanky wood, do this in early spring; if the shrubs are healthy but show much dead wood, do this after flowering ends.
Tall, over-vigorous shrubs can be cut back fairly severely in early spring, but it is usual with this family to thin out only to preserve shape. Few of them need pruning until they reach an advanced age.
Consult your nurseryman as to the rhododendron variety which would be most suitable for your soil and the position of your garden and climate.