Answer: You can cut them back very hard, as hard as needed to reestablish a bushy framework. Typically you might cut them back by two thirds to a half. They should resprout from buds along the old stem. Some gardeners root the trimmings and use them in the garden as well. Try to get them into the brightest possible location as soon as you can because they will be leggy as a result of low indoor light; setting them outside on sunny warm days would be ideal.
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