How to Tier a Sloping Garden

Updated February 21, 2017

Flower and vegetable gardens present long, blooming rows of colour and productivity in the home landscape. Any garden requires a flat, even growing surface for drainage, as well as sufficient exposure to sun and air. Gardens on hills or sloped land experience erosion, puddling and cold air; such gardens require careful planting and maintenance. Terraced gardens bring a decorative look to a hillside and produce small, healthier growing beds. Divide your sloped garden into smaller beds, with well-placed retaining walls to terrace the area.

Begin your project in spring or summer, when the soil is soft and easy to dig. These starting times also allow for immediate plantings. Measure out 4-by-6-foot or 6-by-8-foot plots for manageable, even tiers. Place the beds in straight lines or stagger them for a more decorative look.

Mark each corner of each bed with a stake to outline the borders. Connect the four stakes of each bed with twine to further define them. Wrap the twine around the bottoms of the stakes at the high ends of the beds and the tops of the stakes at the low ends; then adjust the twine up or down on the stakes until they are level in every direction; verify the true horizontal measurement with a level. The twine marks the height for the top of your retaining wall.

Dig 2-inch-deep trenches along the borders of the bottom and two sides of each tier. Dig the trenches wide enough for the blocks, stones or posts that you choose for the wall. Run the trenches three quarters of the way up the sides. The trenches will be the footers for the wall.

Lay the material for the wall in the trenches. Stack the material along the bottom wall to build it high enough to reach the twine. Repeat this process on each side to the end of the trench, resulting in three walls of the same height. The height should match the high ground that makes up the top border of each tier.

Fill each garden bed with a mixture of half organic compost and half bagged garden soil to give the garden a deep, rich and loose growing foundation. Add 13-13-13 granular fertiliser, per the manufacturer directions, to add nutrients.

Things You'll Need

  • Tape measure
  • Stakes
  • Twine
  • Level
  • Shovel
  • Blocks, stones and/or posts
  • Organic compost
  • Garden soil
  • Fertiliser
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