Jennifer Schultz Nelson
Extension Educator, Horticulture
Winter is not a season that most Midwestern people think of finding great tasting fresh fruit for sale. But actually winter is prime time for finding great citrus fruit available at your local market. Grapefruit is very commonly available, but most people don't give it a second thought, some even think it is boring and not exotic in the least.
The thought of grapefruit conjures up an image of my dad in my mind's eye–for most of my childhood he ate half a grapefruit as part of his breakfast each morning. My image of grapefruit was it was sour and something dads like to eat. I could only stomach it with half an inch of sugar layered on my half.
Grapefruit (Citrus x paradisi) is a pretty recent addition to the world of citrus. It was first described in about 1750, and specimens were collected from the island of Barbados, where it was first found, and described as the "forbidden fruit". Compare that to sweet oranges, which had been known in Europe since the 1400's when Portuguese traders brought them from India.
Explorers first thought the grapefruit was a spontaneous mutation, or sport, of the citrus fruit named pummelo. It wasn't until about 1948 that scientists began to dissect the pedigree of the grapefruit, and evidence mounted that the grapefruit was an accidental hybrid of the pummelo and the orange.
Grapefruit grows on trees, just like other citrus. When it was first cultivated from seeds and seedlings gathered from the wild, people planted it as a novelty. No one thought of eating the fruits.
The trees are beautiful, remaining evergreen throughout the year, typically reaching about eighteen feet tall, some growing as tall as forty-five feet. The trees produce sweet smelling flowers nearly two inches across. The first known grapefruits had yellow skin and were about four to six inches in diameter with yellow or pink segmented pulpy flesh.
It was only in the late 1800's that people began eating the grapefruit, and a new branch of the citrus fruit industry was born. The first citrus nurseries were planted in Florida around 1870, and by the early 1900's grapefruit was an important crop in the United States.
Though the first commercially grown grapefruits had yellow or pink flesh, we usually think of grapefruit having nearly red flesh. The first red-fleshed cultivar, 'Ruby Red', was patented in 1929, found as a single red-fleshed fruit on a tree filled with pink-fleshed fruit.
'Ruby Red' became extremely popular, was used by plant breeders to develop other red-fleshed cultivars. Breeders have also selected for fruits with more sugar and less bitter taste typical of early cultivars. Grapefruit are propagated typically by grafting the desired cultivar onto specific rootstocks, much like other fruit trees.
Unfortunately for those of us in the frigid Midwest, growing grapefruit in our landscape is not an option, unless we have room for a tree in a container that we can overwinter indoors. Grapefruit trees flourish in warm subtropical climates like southern California, Texas and Florida.
It takes anywhere from seven to thirteen months for a grapefruit to develop and be mature enough to harvest. If a tree blooms and is pollinated in the early spring, the grapefruits are not ready to harvest until at least September or even later. Mature fruit may be left on the tree until ready for sale and shipment.
December and January are prime time for citrus harvesting. In citrus-growing regions that occasionally see frosts and freezes, a dip in the temperature below freezing in late fall and early winter could mean large crop losses for farmers.
Grapefruit is a good source of Vitamin C and fiber. Red- and Pink-fleshed cultivars have the pigment lycopene, which research has shown has health-promoting properties. Lycopene is a red-colored pigment that is also in tomatoes, watermelon, red bell peppers, and papaya.
Grapefruit is a healthy food choice, but studies have found it can interact with certain drugs, increasing their potency. Check with your doctor for more information.