When Are Yellow Ruby Grapefruit Ripe?

Timing of Harvest

• As with other grapefruits, the earliest "Ruby" grapefruit ripens in November and the harvest continues through March. Because below-freezing temperatures can ruin citrus fruit development, your grapefruit trees must be protected from frigid weather. Although in-ground grapefruit trees do best in U.S. Department of Agriculture plant hardiness zones 9 through 11, they can be grown in zones 4 through 8 in containers if you bring them indoors for the winter.

Leaving the Fruit

• Just because your grapefruits may be ready to harvest in November, doesn't mean you have to pick them. In fact, you may want to leave them as long as your patience will allow. The longer the fruits stay on the tree, the sweeter they will become. Extra time gives the sugars within the flesh of the grapefruit to develop, leading to grapefruits that can be nearly as sweet as some oranges. If you prefer tart grapefruit, harvest your "Ruby" trees early, but if you like sweeter citrus, put the harvest on hold until late winter.

Determining Ripeness

• The University of Florida states the best way to determine if your grapefruit is ripe is to taste one. If you like the flavor, harvest the fruit. To decide if your grapefruit is ready for tasting, feel and smell will be your best clues. The fruit should feel heavy for its size; light fruits are mainly pith and haven't fully developed. The fruit should also have a slight give when you press it. If the fruit feels hard, leave it to ripen longer. A ripe "Ruby" should also give off a fragrant and tart citrus smell when pressed.

Harvesting and Storing

• To prevent breaking your tree, harvest your grapefruit by giving a light tug as you give a quick, clean twist to the fruit until it snaps off the branch. Because the fruit won't ripen further once it's picked, only harvest what you'll eat and leave the rest to ripen further. If you pick more than you plan to eat right away, don't wash the fruits. The wax that naturally grows on the rind helps keep the grapefruits moist until you're ready to eat them. The fruit will taste best if they are kept at room temperature and eaten within a week of harvest. If you need to store the fruit for longer, wrap each grapefruit in tissue or newspaper and keep them in a cool, dry area. If you don't have room to store your "Ruby," you can leave them on the tree until you're ready to eat them.