Acacia dealbata is a hardy, fast-growing evergreen tree that produces lovely, fragrant yellow flowers. Its common name -- silver wattle -- comes from its silvery grey leaves. However, the amount of pollen this tree produces may trigger an allergic reaction in asthma sufferers. Prune a young silver wattle regularly to promote vigour, shape it to the desired size and keep it looking bushy and attractive. Pruning also prevents seed development and hampers its invasive tendency.
Prune in late spring after the silver wattle flowers. First, cut off the spent flowers with a cut 6.5 mm (1/4 inch) above the base of the flower.
Cut off any portions of the silver wattle that have been damaged by winter weather or shading. Cut at an angle with the sharp point facing the outside of the plant, the direction in which you want to encourage growth.
Remove any crossing branches or branches growing toward the centre of the tree. Thin the plant as needed by selectively cutting off branches to promote light penetration and improve air circulation for the leaves.
Cut off up to one-third of the oldest, thickest branches if your silver wattle has grown too large or become badly damaged. The silver wattle responds well to hard pruning and should thrive after you have cut it back.
Continue with constant minor pruning, or tip pruning, throughout the growing season to encourage a compact, bushy tree.
Cut off the very top of the main vertical leader when your silver wattle reaches the height you want.
Expect your silver wattle to last 10 to 12 years.