My hedge was about 7 ft but I could have stopped trimming it and it would have gotten twice that. I planted in two rows. about two ft apart. kind of zigzagging the spacing to fill in so that it would be good and thick when it matured. That is why I trimmed it after each season, from the first year, to be sure it put out lots of branches when it was still small. If you just let it grow it will get full at the top and thick 3/4 inch to 1 inch trunks at the bottom.