Green ash trees grow very quickly. Hardy in USDA zones 2 to 9, they do well over a large part of the United States, according to the Arbor Day Foundation. Green ash trees are useful as shade trees. A tree can grow to 50 or 60 feet, with a spread of 25 feet.
Plant your green ash tree in full sun. Green ash trees can tolerate almost any soil--acidic, alkaline, loamy, moist, sandy, well drained or wet, according to the Arbor Day Foundation. Dig a hole as deep as the root ball and two times as wide. Place the tree in the hole and fill the hole with soil. Build a 4-inch-high barrier around the tree about a foot from the trunk. Fill it with mulch, and water it until it reaches the top of the barrier. Keep the soil around the tree moist at all times while it is getting established.
Water the green ash tree well. It is not very drought tolerant, and in areas with little rainfall it needs to be watered for 15 minutes once a week.
Prune the tree in the spring, after it starts to sprout leaves. Remove any broken, diseased or dead branches at the base of the tree. Prune any crossing or vertical branches, as well. A good green ash tree should be shaped with a strong central leader. All other branches around it should be pruned.
Fertilize the green ash tree once a year in the spring with a 10-10-10 water-soluble fertilizer.