How to Make a Raised Flower Bed With Cinder Blocks

Mark out the bed's length and width on the ground using spray paint. Consider the width of the cinder blocks when determining your raised flower bed's final size.

Dig a trench 6 inches deep and wide enough to accommodate the cinder blocks. Use a hand tamper to tamp down the trench. Place a level in the trench and fill in any low spots, tamping them down. Work your way around the entire trench with the level until you have a sturdy base.

Fill the trench with approximately 4 inches of crushed gravel. This is especially important if you live in an area where the ground freezes. During freezing and thawing the ground heaves. The crushed gravel helps protect the cinder blocks and keeps them from being moved around too much.

Lay the cinder blocks in the trench. Push them tightly end to end. Lay a level on top of the blocks. Place dirt under any low areas. Butt the cinder blocks up at a 90-degree angle at each corner.

Place another row of cinder blocks on top of the first row for a slightly taller raised bed. Stagger the cinder blocks so that the first layer's joints touch the center of the cinder block above. This gives the raised flower bed more stability.

Measure the height of the raised flower bed. Use a metal cutting hacksaw to cut a piece of rebar approximately 4 inches taller than the bed's height. Place a piece of rebar into every other cinder block hole. Hammer the rebar into the ground approximately 4 inches. The rebar helps support the cinder blocks. Skip this step if your flower bed is only one cinder block high.

Pour a bag of dry cement into a wheelbarrow. Add water according to the manufacturer's directions and use a shovel to stir the mixture. Pour the cement into each of the cinder block's holes. Use a trowel to smooth the cement's surface, giving the flower bed's top a finished look.

Allow the cement to harden for 48 hours. Fill the raised flower bed three-quarters of the way full with dirt. Finish filling the bed with top soil. Plant your flowers.