Satsumas are known for their ease of peel removal and their virtual absence of albedo, that fleshy white layer that comes between peel and pulp in many citrus types, especially grapefruit. As you may have surmised, the origin of ‘Satsuma’ is Japanese.
The fact that Satsumas grow in both Japan and Korea is evidence of their cold tolerance and they can be found in Northern California gardens, too, as long as temperatures stay above 20 degrees centigrade. Their fall ripening period, before winter cold sets in, is also in their favor when it comes to finding a home in areas where other citrus fruit, whose ripening period includes winter months, would freeze.
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.
Prune your mandarin orange tree, as needed, to remove broken, diseased or dead branches. Use only sharpened and sterilized pruning shears when pruning your mandarin orange tree to avoid the possible spread of disease.