The Earleaf Acacia, Acacia auriculiformis, is hardy in the U.S. Department of Agriculture zones 10 and higher. It is a fast growing tree, attaining heights of 95 feet in a short amount of time. This tree can grow around 8 feet per year. The yellow flowers grow on short spikes and the leaves are flat, 8 inches in length.
Earleaf Acacia trees are used for tropical reforestation. When planted, this tree puts nitrogen in the soil and it smothers imperata grass. People often use this tree for firewood or pulpwood because it grows so quickly.
Earleaf Acacia trees will grow in almost any type of soil. The pH levels can vary between 9.0 and 3.0 and the Acacia grows strong. Even moisture whether lack or abundance can stop this tree from growing once it starts.
Find a location that offers the full sun exposure. Because this is a large tree, you need to make sure it has enough room to grow without doing damage to buildings, highline wires, fences or other structures.
Preparing the Site
Clear an area of weeds and grass in a 4-foot diameter circle. Place 3 to 4-inches of organic compost over the cleared area and then dig or til the soil until it is fine and loose. The compost helps with drainage, and provides nutrients for the tree. If the soil is dense, add more compost along with builder’s sand to lighten it up.
Dig a hole that is twice as wide and twice as deep as the Earleaf Acacia’s container. Scuff the sides and bottom of the hole with the edge of your spade so the roots can easily penetrate beyond the walls of the hole.
Backfill the hole with soil until it is two-thirds full.
Remove the Earleaf Acacia plant from the container. Be careful so you don’t break the soil around the roots or this can set the plant back and cause it stress.
Before placing the rootball into the hole, examine it for roots. If the roots are visible, tease them away from the sides and bottom with your fingers. If the roots have begun to curl, simply trim them back with sterilized pruning shears. Remove any roots that are broken or mushy because if left on the tree, they are an entryway for disease.
Place the Earleaf Acacia’s root section in the center of the hole. The top of the rootball should be 1/4 to 1/2 inch above the surrounding soil, but not lower. The soil beneath it will settle bringing the rootball level with the ground. Adjust the soil as necessary.
Check that your tree is standing straight and then begin backfilling the hole with soil. Tamp the soil with your hands as you go to remove air pockets.
Water the Earleaf Acacia thoroughly. This will further collapse air pockets in the soil and bring the rootball level with the ground. Keep the soil evenly moist until the tree is mature. For those living in a dry climate or if your area is going through a drought, provide an inch of water each week.
Place a 2 to 4-inch layer of organic mulch over the soil. Keep the mulch 1.5 to 2 inches away from the bark of the tree. If the mulch is allowed to remain against the bark, it will keep the area damp, which can lead to rot of disease.
Fertilize newly planted Earleaf Acacia trees every 15 to 20 days with a low-nitrogen fertilizer. After the tree becomes established, continue using the low nitrogen fertilizer, but feed it every 4 to 6 weeks.
Check the Earleaf Acacia tree for pests like mites, flies, wooly aphids, thrips, and goat moths. See your county extension agent for the best way to deal with these pests.
Watch for anthracnose. This fungus can quickly claim a tree if left unnoticed or untreated. It attacks young stems and phyllodes. The signs of this disease are dark brown, circular, or irregular spots with gray centers. To treat your tree, spray it with a fungicide that is safe for Earleaf Acacia trees.