Mandarins, prized for their sweetness and bright peels, are low-maintenance citrus fruits that are among the most cold-tolerant of citrus. Field research by the Texas Cooperative Extension identified the satsuma mandarin as the best quality and most cold-tolerant of all mandarins. Mandarins usually alternate bearing years, with a light crop followed by a heavier crop the next season. When growing a satsuma mandarin orange tree, you should care for the plant with cautious watering, light feeding, some weed control and protection from severe freezing.
Build a "watering ring" around very young satsuma trees to help with watering. Use good quality garden soil to construct a ring about two feet across and several inches high. Fill the water ring slowly with water from a garden hose and allow it to soak in. Do not remove soil from around the tree to create a watering basin--this will cause foot rot (a disease that causes the stem base to rot) and kill the satsuma.
Supply one cup of ammonium sulfate (21-0-0) divided into three applications over a year for just-planted trees. Sprinkle the fertilizer over the ground around the tree and water it in. Use two cups the second year and three cups the third year. Use one cup per year for older trees; apply fertilizer in February, May and September.
Remove grass and weeds within the watering ring around young trees; mandarins do not compete well with weeds and grass. Use a systemic herbicide if necessary, but don't let it touch the bark or leaves of the tree. Avoid using mulch around your satsuma mandarin; mulch increases the odds of foot rot in citrus trees.
Provide support for the branches of a satsuma mandarin; they grow into a more erect shape than most citrus trees, and the branches may droop. Protect the brittle branches from breakage by propping them up with poles or boards.
Protect your tree from hard freezes. According to Texas A&M University, mandarins should be planted on the south or southeast side of a building for maximum protection. Use a tarp or protective cover--or a portable heater--during unusually cold weather.
Move a potted satsuma to at least a 20-gallon container if you plan to keep it potted. Satsumas do well as container plants but do not grow much taller than six feet in containers.