I bought THORNLESS blackberry plants online for about $2 each.

Depends what climate you live in.
Here in Canada
For best results , you have to winter the berry…
Put some berries in a sealed container , in the fridge . for at least a month.Then plant in potting soil , and grow seedlings under fluorescent lights until spring..
You can also take cuttings in spring , from existing plants..
Dip the cutting in a rooting hormone,,Plant in a potting soil , and keep well watered..
Once cutting shows signs of growth..about 6 weeks… Transplant to garden..
You may be lucky by just planting some berries in the fall. Nature will winter,, and you will get some sprouts in the spring….
I have many plants like this,,,Raccooons eat the berries,,poop them out, by the fence,,and I have new plants the following year…
Good luck

Yes; it can. But, you might have a better chance growing them by buying packaged blackberry seeds since of the manufactures add some growth hormones and theirs are grown in a perfectly suited environment where-as an average gardener only meets about 85% of the plants basic needs; also the weather and animals can harm your plants thus causing some negative effects.

The choice is yours; I personelly like packaged seeds since to me, they grow better but, I have also had great luck with the plants seeds and not packaged ones.

First of all…are you sure you want to grow a blackberry plant? Once planted they quickly overtake an area…very thorny, but it’s your choice.

You can grow blackberry plants by seed and by taking a cutting, use Rootone (or other plant hormone).

These tasty berries are wonderful to eat, but make sure that you have plenty of room and that they don’t “go wild” on you.

You need to take the blackberry plant that had berries and cut it down in the fall, they will not grown anymore, next to the old plant there will be a new shoot that didn’t have any berries this season, those will bear the fruit next year. You can dig up a plant and plant it in your garden. Make sure you take the time to prune them every fall or they will overtake your garden.