Rio Red Grapefruits
Large, fragrant blooms and nearly white flesh make the Rio Red a standout variety. Sweeter than most grapefruit and great for juicing, ëRio Redísí juicy red flesh is a favorite at breakfast. Importantly, it is more tolerant of cold than other varieties. You can enjoy these citrus trees indoors in winter and on the patio all summer long. Hardy in Zones 9ñ10
The Rio Red a relatively new variety was introduced in 1984. It has few to no seeds, and is more vigorous and hardy than the Star Ruby and the fruit is sweeter than the Ruby Red.
In 1993 the Texas Legislature designated red grapefruit as the State Fruit of Texas. The Texas citrus industry annually produces more tonnage, about 80% of which is grapefruit, than all other tree fruits and nuts in Texas combined. The quality and importance of Texas red seedless grapefruit helped it obtain this prestigious designation.
Grapefruit apparently originated as a natural mutation of the shaddock or pummelo somewhere in the West Indies. The first record of the term grapefruit occurred in 1814 in Jamaica. Count Odette Phillipe, a Spanish don, is credited for its introduction to the United States who planted it in Pinellas County, FL, about 1823.
The major grapefruit varieties in Texas are Rio Red, Ruby Red, and Henderson/Ray. All were discovered in Texas and all are red-fleshed, seedless and have varying degrees of redness in the peel.
Rio Red was discovered in 1976 by R. A. Hensz as a limb sport on a tree being grown from 'Ruby Red' budwood. Released in 1984, Rio Red has interior color that is twice as red as the "Henderson" and its color persists throughout the season. 'Rio Red' has an overall reddish tinge on the peel & a lighter colored halo in the flesh when viewed in cross-section.
Mature Tree Care
Watering of your Rio Red should be slow and thorough; probably every week or two would suffice in any but the very sandy soils. Nutrition should continue at about 1 cup of ammonium sulfate per year of tree age annually with split applications in February, May and September. You'll need to adjust the rate for other fertilizers based upon the relative nitrogen content.
No pruning should be necessary, as the grapefruit tree will develop its natural shape without pruning. While mulching is not recommended for citrus trees, if you must mulch, keep the mulch at least one foot away from the tree trunk.