While avocado trees can grow quite large (30 to 60 feet), dwarf avocado trees exist that are suitable for container growing. The trees should be planted in the spring or fall and left outside in a sunny location. Container avocado trees will bear full-sized fruit. Different types vary widely in their fruiting time; avocados ripen from spring to winter, depending on the type of tree. Dwarf avocados require the same care and attention as standard trees.
Cut a piece of mesh screen to fit in the bottom of the 5-gallon container. This prevents soil from washing out of the bottom of the container. Then fill the container one-third to half of the way full with a mixture of equal parts topsoil and potting mix.
Pull your dwarf avocado tree from its container. Break apart the root ball by rubbing it between your hands. Untangle roots, and break up any soil clods. Check the roots and clip the ends of any broken or damaged ones.
Place the dwarf avocado tree in the container, spreading the roots out against the soil. Fill in the container with your potting mix/topsoil blend. The tree should be vertically straight, and planted at the same depth as it was in the container.
Water the newly planted avocado tree until the soil becomes saturated, and water flows out the drainage holes at the bottom of the container. Place the container in a location where it receives full sun; avocado trees need sun to ripen.
Fertilize a young avocado tree with two tsp. of a balanced fertilizer (such as 10-10-10) per year. Divide this up into four applications of half a tsp. each. Scatter the fertilizer around the container, then water to work it into the soil.
Water the avocado tree whenever the soil becomes dry and crumbly to the touch. Stick your finger a couple of inches into the soil to test the moisture there.
Move the container avocado indoors in the winter if you expect a frost. Avocado trees are cold sensitive. The most cold-tolerant avocado (Mexican) gets damaged at 19 to 24 degrees Fahrenheit.
Prune dwarf avocado trees annually, using anvil pruners. Remove dead or damaged branches and suckers sprouting from the base. Clip off branches that crisscross or compress other limbs. Remove vertically growing branches that shade the tree. Trim back long branches to the desired height.