How much room for mothers.

You can keep it however small you like.. 1x1 being about the smallest I’d do.. You’re just restricting your ability to take a decent quantity of cuts at anytime. Depends what your end game is. If you’re trying to take a few dozen cuts all at once.. this won’t work. But if you want a clone or two here and there it’s fine. You will, however, have to continually prune and keep it cut down to size. Ultimately, I’d recommend a bit larger size. I run 8-12 in a 4x8 and it works well. I can take a dozen or so clones from any one at a time. Keeping moms just takes a little different shift in maintenance / mentality compared to vegging out plants for flower. I run low lights on them and keep containers smaller so they grow slower. Nutrients at a minimum. But it’s a fine line because you want them healthy enough to take clones.