Square pots allow you to make the most of your garden space. By using normal round pots, there will always be gaps between the pots which is not being used for your plants roots. Square Pots allow you to completely fill your garden floor-space, maximising root-space which gives you increased growth capacity and potential yield.
Square pots are used exactly like round pots. Simply fill the pot with your soil/coco/clay mix leaving an inch or 2 at the top for ease of watering. Transplant your cutting/seedling/plant into the mix and water well.