With over 800 species of trees and shrubs, the acacia genus is one of the largest in the plant kingdom. Acacias are easily grown from seed, but getting seeds to germinate in a controlled environment can sometimes be tricky. As members of the legume family, acacias grow pods containing the seeds. When ripe, the pods split open to release the seeds. For the best seeds, collect the pods when they have turned brown but are still closed.
Squeeze the ripe pods to make them split open and release the seeds. The seed coatings are very hard and must be softened or broken down to allow water to penetrate. In nature the hard coating is broken down by the heat of grass and brush fires. This effect is simulated by using boiling water.
Place the seeds in a shallow bowl and cover with boiling water. Some species only require a very short exposure to heat to soften the coating. This is usually true of acacias native to grassland areas where fires burn through very quickly. In this case the seeds should only be exposed to the boiling water for a minute or two and then cooled off. Seeds from species native to wooded areas can be left in the bowl for 12 to 24 hours.
Examine the seeds after the heat treatment. The seeds will become swollen if the coating has been penetrated. These seeds are ready for planting. The boiling water method can be repeated with any seeds that are still hard. If the heat method fails to soften the coating, try rubbing the seeds gently between a folded piece of fine-grit sandpaper. This will scarify the coating and make it easier for water to get through.