Q: I was given a miniature orange tree and it has flowers on it. Will they turn into edible oranges?
A: If it was sold as a houseplant, it is likely a calamondin orange. They produce inch-wide fruit that looks a lot better than it tastes. They are edible, but are very sour.
To get fruit indoors, you may need to pollinate the flowers. This can be done with a cotton swab. Lightly touch the fuzzy parts that contain pollen and then the sticky parts. They don’t need a lot of pollen, so don’t worry if it looks like most of the pollen is still on the swab. You can use the same swab to move from flower to flower. The flower petals will eventually fall off, leaving a bump. It can take up to a year for this bump to turn orange and be a ripe, edible fruit.
Citrus need a lot of light and soil that is well drained. Let the surface dry between waterings. They really benefit from spending the summer outdoors. Scale and spider mites are often a problem, especially in our dry winter homes, so check them with every watering. Wash off the insects as soon as you see them. Insecticidal soap can be used. There are also some systemic insecticides like imidacloprid that are labeled as safe for citrus, but they are harmful to pollinating insects. This isn’t such an issue if your plant is indoors when flowering; so far, there are no reports of it killing a cotton swab. But, you need to decide whether you want to eat the fruit after using it. Newly purchased plants may have residual systemic insecticides in their fruit.
If you are looking for a citrus with edible fruit, try a Meyer lemon. They are easy to grow and take less time to ripen than oranges, and if you can find the delicious fruit in a store it is often expensive. Kaffir limes can also be grown indoors. Their edible leaves are used in Thai cooking.
More on growing citrus as a houseplant can be found at extension.umn.edu/house-plants/growing-citrus-indoors.
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