During the month of June, we pick close to a gallon of blackberries every day! Below, a few raspberries on top!
A few years ago I transplanted about a half a dozen plants from the garden by my home out to the community garden where they could be in full sun. What a difference that has made! After many years of puny plants and minimal harvest, the blackberries have exploded, both in the output of berries and in the proliferation of plants.
One way blackberries reproduce is by sending out long canes that eventually curve down to the ground, where they take root, becoming a new plant.
You can dig these up to transplant or leave them be. I have done some of both.
I started with one row of blackberries and one of raspberries, but the blackberries are overtaking the raspberries. I transplanted the raspberries, moving them farther away, and expanded to three rows of blackberries. The blackberries are a thornless variety (I am not sure which one) with huge berries that are full of flavor and very sweet when fully ripe. Since I don’t eat a lot of jelly, we use them primarily for blackberry/blueberry wine.