How to Care for and Prune Satsuma Mandarin

Mound the soil around the base of the tree 5 inches away from the trunk and 2 inches high. Create a moat around the mound to hold water. This keeps the roots from becoming soggy and allows you to fill the moat so the water can drain slowly and evenly to the roots when watering does take place.

Water every couple of weeks with the equivalent of 2 inches of water. Add it slowly to the moat so it has time to soak in before it runs off.

Apply ammonium sulfate to increase nitrogen and keep the soil slightly acidic. The plant should be established by the time of the first feeding. Fertilize in early spring before bud break. Use 1 cup per year of the tree's life. Mix it into the soil from 2 inches away from the trunk out to the drip line. Water after fertilizing until the soil puddles.

Keep weeds and other competing plants away from the base of the tree. Spread 3 inches of organic mulch from 3 inches away from the trunk out to the drip line. Keeping the mulch away from the trunk helps prevent rot.

Train the tree at planting to a central leader. Choose the straightest and strongest vertical growth and encourage evenly spaced lateral branches. Remove any suckers or other vertical growth.

Prune in August to September. Prune off water spouts, suckers and dead wood. Encourage the formation of a structurally even tree with room between branches. Leave horizontal wood.

Thin the fruit just as it begins to set. Each fruit needs to have 20 to 25 leaves near it to provide the energy for the fruit. Estimate the number of leaves on the trees and thin the fruit by hand to a corresponding amount. For instance, for a small tree with only 100 leaves, leave only 4 to 5 oranges to develop.