Steven H.
BOTANIC NAME
Acacia
COMMON NAME
Wattle
NOTE
Acacias are trees and shrubs highly sort after for their small yellow flowers, which grow profusely in fluffy little pom-poms. Possibly the best for bonsai are A. paradoxa (Kangaroo Thorn) and A.podalyriifolia (Queensland silver wattle), which will tolerate higher winter temperatures. Acacia has a bad reputation as being a short lived tree however with care, regular repotting in good soil and correct watering it can live for many years.
BACKGROUND
Acacia is a genus of around 1200 species, 954 of which are currently recognised as occurring in Australia. The next largest occurrence is in Africa. The plants occur in all Australian states from coastal zones to mountains to the dry inland. Collectively the Australian species are known as "wattles" and one of them, Acacia pycnantha, is the national floral emblem. The green and gold colours of the foliage and flowers has provided Australia's official colors.
SUN
Full sun to part shade. Turn plants regularly to achieve even growth.
TEMPERATURE
Wattle will handle light frosts and even coastal conditions.
WATERING
They like a lot of water and fertilizer when in active growth. They require less water in winter, although they should never be allowed to dry completely. Good drainage is essential.
TRAINING
Wattle must be pruned back hard in early spring (after flowering) as they are prolific growers and will quickly loose their shape. Upright styles are more suited to Wattles as some die back and loss of vigour has been noticed when branches are bent below horizontal. Cut back to bare wood at repotting time if required.
FERTILIZING
They like a lot of water and fertilizer when in active growth. Use standard native fertilizers like Osmocote Native etc.
REPOTTING
Be cautious of the long tap root on collected stock. Can be root pruned without difficulty if a healthy and fibrous root mass has been obtained. Repotting is best done immediately before regrowth.
PROPAGATION
"Acacias are best propagated from seed. This is a reliable method which, with most commonly grown species, presents few problems. The seed of Acacia species is shed annually. When the seed is ripe the pods turn brown and split to release the seeds. By keeping watch on the ripening pods it is fairly easy to collect the seed before it is shed.
Acacia seeds have a hard coat which, in most cases, is impervious to water and germination will normally not occur unless some sort of pre-treatment is first carried out. In nature this hard coating is designed to be broken down by the heat of a bushfire to allow the species to re-colonize burnt out areas.
This effect can be replicated in a number of ways but, for most species, the easiest is to pour boiling water over the seeds and allow them to stand overnight. The next day any seeds which have swollen are ready for sowing and can be removed; the remainder of the seeds can be treated with boiling water again and the process repeated for as long as necessary. "
PESTS OR DISEASES
Borers can be a problem with some of the tree species, particularly those in the "Black wattle" group which includes A.decurrens, A.parramattensis and A.mearnsii. These trees often grow very rapidly but then deteriorate after 7-8 years as the damage inflicted by borers becomes more than the plant can cope with.
COMMENTS
Despite having a reputation as a short lived tree, Acacia make a wonderful bonsai specimen. A mass of beautiful yellow flowers in late winter to early spring make for a superb show piece. They back-shoot well and handle cutting back to bare wood so total reshaping is possible. Not only are they good looking but they are also our national floral emblem!
