The blackberry is a small, dark purple fruit, typically considered a culinary berry. It is popular for making jams, wine, and dessert filling.
Since blackberry plants easily hybridize, there are many cultivars with more than one species in their ancestry.
- Dewberries (R. caesius) are smaller than blackberries and can be distinguished by the white waxy coating on the fruits, which also usually have fewer drupelets.
- Boysenberries were bred from blackberries, loganberries, and raspberries.
Blackberries should be dry, firm, well-shaped, dark purple to black, and shiny. Avoid purchasing berries with juice stains which may be a sign that the berries are crushed and possibly moldy. Soft, watery fruit that means the berries are overripe; dehydrated, wrinkled fruit means the berries have been stored too long.
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Blackberries reach their peak towards the end of summer, specifically July to August. In warmer climates, the season may start earlier and end later. For instance, the Californian blackberry season starts in May and ends in October. 
Superstition in the UK holds that blackberries should not be picked after September 15th, as the devil has claimed them and left his mark on the leaves. There is some value behind this legend, since wetter and cooler weather often allows the fruit to become infected by various molds including Botrytis. These molds can give the berries an unpleasant flavor toxicity.
It’s best to buy fresh berries when they are in-season, as they are cheaper, riper, and more flavorful. The fresh berries do not keep long, and they should be eaten within a week after purchase. Moisture will increase spoilage. For longer storage, freeze them in airtight containers for up to several months—a pound of whole frozen blackberries is equal to about 3 cups.
Blackberries may be eaten raw or prepared in a variety of ways. They may be made into sweet sauces and preserves, mixed into fruit salad, churned into ice cream, used as garnishes, and more. Baked goods such as cakes and scones may incorporate fresh or frozen blackberries—if using frozen berries, fold them into batter while still frozen.