How to Level the Edge of a Flower Bed on a Slope

Rake away any mulch or leaf debris on the lower bed edge across the sloped flower bed. Pull the mulch up the slope to expose 18 to 36 inches of bare soil along the lower bed edge. This exposed soil area is where you will construct the level bed edge.

Lay a row of stone, brick or concrete pavers end to end along the lower edge of the flower bed. Choose any size, shape or color of stone, brick or paver to suit your taste. Larger stone or paver pieces are visually more impactful and reduce the need for layering to build an edge. Depending on the topography across the front of the bed, slightly larger stones may be needed to compensate for any low spots; you want the stone edge to look relatively even when viewed from the bottom of the slope looking up into the flower bed.

Place a long, level stick -- a yard stick, scrap lumber piece or broom handle -- atop the stone edge. One end of the stick should be on the edge and the opposite end laying up the slope into the flower bed. The visual line created by the stick illustrates the soil grade needed behind the stone edge to create a level flower bed. Look at the stick from the side. You need to pile topsoil under it to modify the sloping ground, bringing the bed's grade up to the stick. A bubble level tool may be used to ensure the stick guide is perfectly level.

Backfill the bed side of the stone edge with topsoil. Add enough soil to create a level grade that matches the stick guide. Use the bubble level tool as needed to ensure the grade is even and level across the entire work area. The taller the stone edge, the more soil needed to backfill to create a level edge into the sloping flower bed. From the side, the stone edge creates an abrupt, steplike edge at the bottom of the flower bed.

Tamp the backfilled soil with your feet to steady the stone edge. Tamping also prevents erosion and shrinking or settling of the soil. It's better to add a little too much soil than not enough to level the base of the sloping bed. Soil always settles over several weeks after being disturbed and aerated.

Lightly water the backfilled soil around the rock edge. This naturally removes any air pockets and compacts the soil. Add more soil to grade the area as necessary.

Rake the mulch or leaf debris back down the flower bed to cover the backfilled soil. Tamp the mulch or debris down so wind and rain won't quickly move it.