Upright Sedums like 'Autumn Joy' thrive in full sun and well-drained soil. They will flop over if they are in too much shade. Also, the plants can become floppy if the soil is overly rich or fertile. You can reduce your sedums' overall height by cutting them in half each June when they reach 8 inches tall. Sedum rarely needs division; once every 8-10 years in spring is ideal.