Azaleas and rhododendrons are flowering shrubs that need very little care. These plants should be pruned in order to shape the shrub and to reduce the size. Because the plants produce flower buds on the previous year's growth, you should prune azaleas and rhododendrons in early summer, after the spring season flowers fade, but before July, when the buds for the next spring's flowering form. Azaleas should never be trimmed with electric hedge trimmers. This gives the azalea an unnatural flowering habit known as a whiffle cut.
Sharpen your pruning shears prior to pruning azaleas by drawing a sharpening stone along the blades.
Sterilise the blades with a solution of 1 part bleach and 9 parts water. Soak a cloth in this solution and use it to clean the blades of your hand pruners.
Select long branches that you wish to shorten.
Grasp a branch with one hand at a point 12 inches above where you will cut. Prune the branch with your other hand.
Remove broken, diseased branches or those that rub one another or grow inward by cutting them back to the closest healthy branch.
To hide branch stubs, cut each branch so that the stub is below the foliage. Azaleas and rhododendrons will sprout new growth along the trimmed branches immediately. The new growth appears a few inches below the cut. Make cuts a few inches above a sparse area where you want you want additional foliage.
Remove no more than one-third of the shrub's total growth during a single pruning. Azaleas and rhododendrons that have had more than one-third of their total growth removed may never recover and may die.