You need to allow some suckering as that is what provides the stems which will fruit in the following year. Raspberries don't fruit repeatedly on the same stems and need to renew themselves constantly. You can mow along the sides of the row/patch.

You could use a bamboo barrier. I have mine in a 1 ft raised bed and rarely get a sucker outside of it. However I am in CA and it doesn't rain for 6 months so the soil/clay outside the bed is hard for the rasps to move through.

Thanks for the comments. I was considering placing them in a fiberglass bed. If the bed is 6 inches high would that be high enough.

6 inches is fine height wise - but what is this 'fibreglass bed'. Does is have a bottom? How big is it?

It does not have a bottom and it is 42in by 42 in. I was think of placing cardboard or landscape material on the bottom.

if it just sits on the ground raspberries will run underneath it. The side would need to be buried in the soil. I can't say how deep but I'd guess that a foot would probably be enough. The bed is likely big enough for 4 plants. They can be planted about 16 - 24 ins apart. Raspberries run sideways rather than down so there isn't any need for something on the bottom as long as the walls are deep enough in the ground.

thanks. I appreciate your help.