
Mulberry trees are, for the most part, cold-hardy. The three most widespread varieties, red, black and white mulberries, are native to North America and Asia and can all be grown down to US hardiness zone 4 or 5, tolerating the worst of the winter weather.
There are some occasions, however, when cold winds and heavy snowfall can damage mulberry trees, namely when the specimen is young, has been recently planted in fall, or if you grow fruit trees in pots.