A single leaf can produce many young plants, which you can use to increase your own stock of begonias or give to friends. This technique can be used for all begonias but is particularly useful for foliage plants such as Begonia rex.
Cut a young, clean, healthy leaf from right at the base. Cut off its stalk.
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Make slashes along the underside of the main vein. Pin the whole leaf down onto firmed, moist compost.
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Warmth and moisture will encourage growth at the damaged parts of the vein. Several young plants will form on each leaf.
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Roots and new plants will develop from the vein at the base of each cutting. You can tease the pot of plantlets apart and grow them on separately or transplant them as a group to produce a bushier pot plant.