Slope & Drainage Planner
Measure the grade of an uneven yard, lay out terraces or contour beds, and size the swale, drain, dry well, or rain garden that handles your runoff.
Stake the high point and the low point. Run a string between them, level it with a line level, then measure straight down from the string to the ground at the low stake — that's your rise. The horizontal string distance is the run.
Noticeable fall. Runoff starts moving soil during heavy rain.
Contour beds plus mulch. Add a swale or berm above the garden to slow water.
Essentially flat. Water may pond instead of running off.
Plant normally. Watch for soggy low spots — raise beds 8–12 in if water sits after rain.
Ideal garden grade: drains well without eroding.
Run beds across the slope (on contour). Little to no earthwork needed.
Noticeable fall. Runoff starts moving soil during heavy rain.
Contour beds plus mulch. Add a swale or berm above the garden to slow water.
Hard to mow or push a wheelbarrow. Real erosion risk on bare soil.
Terrace it. Short retaining walls (12–24 in) with level growing benches between.
Steeper than 1:5. Bare soil will wash; walls over 3 ft usually need engineering.
Terrace in stages, or plant deep-rooted perennials/groundcover and garden elsewhere.