Acacias are warm weather trees with compound leaves, and, usually, with nasty thorns. They must be wintered indoors, although they generally like it somewhat cool -- under 64 degrees; however, there are tropical varieties which prefer it quite toasty year round. Acacias are sometimes called wattles or golden mimosa. Lesniewicz says that the term mimosa applied to acacia is mistaken; Ainsworth labels his acacia a mimosa. I'd trust Lesniewicz over Ainsworth any day. Most acacias will bear golden flowers followed by legume pods, but getting acacia to flower in bonsai culture is reputedly difficult.
Lighting: Acacias love lots and lots of light. Move them outside when the weather permits.
Watering: Moderate to slightly dry; allow the soil to dry between waterings. Simon & Shuster's recommends daily misting.
Feeding: Every 15-20 days during the growth period. Use a standard bonsai fertilizer, or a low nitrogen fertilizer to encourage flowering.
Repotting: Every 2-4 years, depending on the age and vigor of the tree. Use a fast-draining soil mix, low in organic material. Reduce top growth in proportion to roots that have been pruned. Best to repot before acclimating the tree to warmer weather.
Styling: Wiring can be done from spring to autumn, every other year. Use caution when wiring, as the branches can be delicate. (and I would add, the tree can fight back! Watch out for those thorns!) In my experience, acacias can become leggy quickly, and tend towards top growth at the expense of lower branches, which sometimes die back. It's essential, therefore, to keep up with constant minor pruning. Acacias have compound leaves, so leaf pruning is futile.
Propagation: Seed or cuttings. Cuttings should be taken in summer and supplied with bottom warmth and rooting hormone. Frankly, I've never gotten any of mine to take. Propagation from seeds seems a better bet, as acacias germinate in high numbers. The seeds do need some special treatment, however, due to their hard shells. Nick the bottom ends of the seeds with a knife or pair of clippers, then place the seeds in a bath of hot (not boiling!) water. Allow them to soak for two days, then sow.
Pests etc.: Aphids, flies, thrips, mites etc..
