By Bonnie L. Grant Poinsettias are familiar plants around the winter holidays. Their bright colors chase winter’s gloom from the dark corners of the home and their ease of care make these plants perfect for interior gardening. Poinsettias are native to Mexico, which means the United States Department of Agriculture poinsettia growing zones are only 9 to 11. But what is the actual cold hardiness of poinsettias? You need to know what temperatures can damage or kill your plant if you are using it as a garden accent. Is Poinsettia Hurt by Cold? In their native region, poinsettias can grow up to 10 feet and produce huge bushes with the characteristic flaming leaves. As a houseplant, these lovely plants are usually sold as container specimens and rarely achieve more than a few feet in height. Once the brilliant leaves fall, you may choose to move the plant outdoors…but be cautious.