In Central and South Florida, people leave out tree-ripened tangerines alongside the cookies and milk for Santa Claus. Ripening in late fall and early winter, tangerines (Citrus reticulata) are also called Mandarin oranges. Their flattened globe shapes are very easy to peel. The fruits become ornamental as they turn orange and decorate and linger on the tree. Tangerine trees grows about 20 to 25 feet tall at maturity and are best in frost-free areas in U.S. Department of Agriculture hardiness zones 9b and warmer in Florida.
Choose quality slow-release citrus fertilizer from your garden center. Try to find fertilizers especially labeled for citrus trees as they contain different nutrient proportions based on Florida's typically sandy, lightly acidic soils. In South Florida, choose a citrus fertilizer with a formula like 8-3-9-3, according to the "Florida Gardener's Guide." Such a formula includes key micro-nutrients like iron or manganese to prevent leaf yellowing in more alkaline soils.
Read the product label directions to determine the amount of fertilizer required for the size of your tangerine tree. The size is determined either by tree height or canopy width or thickness of the trunk.
Scatter the recommended dosage of fertilizer granules around the base of the tangerine, focusing it most on an area 2 feet from the trunk outwards to 3 feet beyond the extent of the tree branches. Sprinkle it evenly and widely. Do this once in March, May, late August and early October.
Consider spraying the foliage of tangerine trees growing on alkaline soils with a chelated citrus spray each January. Trees in alkaline soils (pH over 7.0) tend to develop yellow leaves from nutrient deficiencies. Saturate the new growth and older leaves with the chelated nutrient spray as directed by the label directions. Do this only in January. Pour excess liquid around the trunk of the tangerine tree.
Sprinkle epsom salts (magnesium sulfate) around the tree's root zone every two months from March to September. You can't over-apply epsom salts, but scatter it on the ground in a consistency similar to how sugar is sprinkled on sugar cookies.