Several species of blackberries (Rubus spp.) are native to the U.S. and grow wild. They grow in U.S. Department of Agriculture plant hardiness zones 5 through 10. Once the fruits start to form, it can take several weeks for them to change from their original red color to their fully ripe black color. When they ripen depends on both the climate and the weather.
Climate Affects When Blackberries Ripen
When blackberries ripen depends partly on the climate. Across the U.S., blackberries ripen from around June to August. In warmer climates, blackberries are usually ready to eat in June, while in cooler climates you have to wait until July or August before the blackberries turn ripe. Blackberries are ripe when they turn black all over, with no red or green parts.