Good drainage is essential. A low area that allows water to collect or extremely poor or compacted soil that inhibits water absorption will discourage the most determined gardener. Building raised beds makes it easier to add amendments such as compost and gypsum to improve the quality and drainage of the soil and provides easier access for small gardeners.
Gardens can be built on any terrain, even a hillside. However, gardens located on level ground are less expensive to install and easier to maintain. Soil erosion can be a problem on steep terrain and low spots where water stands are not good for plants or people. A slight slope will allow surface water to drain away. Runoff should flow to a drainage channel or culvert.