In 1934, Ruby Red Grapefruit was the first grapefruit to be granted a U.S. patent. Following freezes in 1949, 1951, and 1962, Texas eliminated its white and pink varieties, and set out to establish its reputation for growing red grapefruit.
Ruby Red grapefruit is of excellent quality, seedless (0 to 6 seeds), red-fleshed, oblate and thin skinned. The fruit usually has a red blush on an otherwise yellow peel. Also known as “Redblush” grapefruit or just “Ruby” grapefruit, Ruby Red is a fast growing tree that can reach 20 to 25 feet tall and wide when planted in well-drained loam to sandy loam soil. Like other varieties of grapefruit, it is particularly frost sensitive, and its fruit can be damaged when temperatures drop below 29 degrees Fahrenheit. Because of this, “Ruby Red” should be grown in full sun in USDA plant hardiness zones 9 through 10.
Generally speaking however, late autumn is when grapefruits are ready to pick. Mature fruit may be left on the tree and, in fact, will sweeten throughout the winter. This method enables you to “store” the fruit for a longer period of time than if you picked it all at once. The downside is that storing on the tree reduces the yield the succeeding year. So, late fall into the winter or early spring is when to harvest grapefruit.