Decide where you would like to have permanent, in-ground flower pots made from the blocks. You can group the blocks together in a pattern, lay them in a line along a walk or driveway, or place them individually to brighten a corner with flowers.
Dig a hole just large enough for the cinder block to fit into, with the two-hole side facing upward. The block should be deep enough so that the top of the block is even with the top of the soil surrounding it.
Place the block in the hole and wiggle it around so that it is firmly seated.
Fill in the space between the outer edge of the block and the soil with the extra soil from the hole so that the block is held in place.
Place sufficient potting soil into the hole, depending upon whether you are transplanting a root ball or starting from seeds.
Transplant the flowers or other plants into the potting soil. Place the seeds as directed by the package instructions.