Satsuma Ripening Problems

Optimum Temperatures

• Satsuma mandarins originated in Japan, probably on the northernmost island of Kyushu, sometime before the 1600s. Satsuma needs different growing conditions from most other citrus trees, thriving in areas with warm summers and winters too cold for other citrus. It does not grow in typical mild-winter citrus areas of California, Arizona and Florida because of its sensitivity to hot weather, but grows best in subtropical areas that have colder temperatures or higher elevations. The warm but not hot summers allow early fruit maturation, and colder night temperatures promote ripening.

Fruit Color Change

• The color of ripe satsumas varies depending on the variety. Under good conditions, "Owari" and "Wase" have orange skins. "Kara" can have either a deep orange or yellow-orange skin. "Brown Select" has a yellow-orange color, and "Early St. Ann" has a yellow exterior. In humid subtropical conditions, the skin doesn't change color when the pulp is mature, sweet and edible. Sometimes mature, internally ripe but externally green satsumas are marketed as "Emerald Green" satsumas. When the fruit retains a green exterior, a common occurrence with "Owari," it's more difficult to tell when it is ripe and ready for picking. The Louisiana State University Agriculture Center recommends picking satsumas as soon as they show some yellow color.

Ripening Season

• Satsumas are the earliest citrus fruit to ripen. Cultivars differ in length of time to fruit maturity, and the expected dates of harvest can help determine when they are ready even if the fruits are still green. Satsumas don't keep well on the tree once they are ripe, becoming insipid and puffy. Pick mature fruits immediately, cutting the stems rather than pulling them loose to avoid harm to the thin skins. Satsumas keep well off the tree if stored properly. An exception is the variety "Kimbrough," which keeps fruit well on the tree when they ripen in early to mid-November. "Owari," the most widely planted variety, has fruits ready to pick from early November into December in Louisiana. "Wase" ripens very early. "Kara" matures late in the season. "Armstrong Early" ripens 30 to 40 days earlier than "Owari." Two other early cultivars are "Early St. Ann" and "Louisiana Early," both ripening in early September into October. "Brown's Select" is ready midseason.

Other Problems

• Occasionally the fruits are threatened by early hard freezes while they're still maturing. Use different techniques to protect fruit from harm so it can finish ripening. Often trees are planted on hillsides so the coldest air can drain away. You can plan a wooded shelter belt above the satsumas for a windbreak and to deflect cold air from the citrus. Plant a backyard tree in the most protected, favorable microclimate available. Cover individual trees with frost blankets or burlap during freezing weather, taking care not to let the material touch the branches. Another problem is sensitivity to rainfall, with fruits spoiling rather than ripening after heavy rains. The variety "Armstrong Early" is especially susceptible to rain damage. Plan to harvest satsumas in advance of rainstorms.