A dwarf grapefruit tree. (Photo: Flickr/C Jill Reed)
Q: I have a dwarf grapefruit tree (ruby red grapefruit) in my apartment and it has one huge grapefruit growing on it. It's late January and the fruit has been growing for a couple of months now (hasn't changes size since November) and is some shade of greenish yellow. The size seems normal for grapefruit, but the color is still far from orange. How do I know it's ripe or what can I do to make it ripe?
A: I have a large tree outside (in California), and the fruit is ready in January-February and will last on the tree into August. Depending on how much light the tree gets the skin may not fully change color. Usually about 7 months after blooms set fruit is the fruit fully ripe.
My grapefruits start green and turn a very pale yellow, not orange. If the fruit has been on your tree since April, it is ready. They do not have to change to fully yellow in order to be ripe.
Remember grapefruit, as well as other citrus, are sun lovers and grow outside in full sun. Growing it indoors, you should have a plant light (fluorescent) on the plant at least 8 hours per day.
-- Answer from Steven Giguere, landscape architect on JustAnswer.
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