If your yard is not flat, you may think it will be difficult or impossible to grow a garden. On the contrary. Plants are resilient, and can be grown on almost any grade of hillside. Growing a garden on a sloped yard takes a little more work than those grown on flat land, but it can be done with some minimal preparatory work. After this initial work, the plants will grow just as easily as those grown in traditional garden beds.
Prepare the sloped yard for a garden. Remove any grass, weeds and rocks in the soil. Remove the roots of the the grass and weeds so that they will not grow back. Break up the soil with the spade.
Create trenches that are 3 to 4 inches deep with a hoe. Space these rows approximately 18 inches apart (from the bottom of the hill, upwards) so the trenches run left to right.
Place fence boards sideways into the trenches to help keep your seeds or seedlings from washing away with watering or rain, and to prevent erosion.
Tamp the loose earth around the fence boards, so that they are held securely into place.
Water the sloped garden thoroughly, moistening the earth several inches deep. Wait about an hour to let the first few inches drain a little.
Plant the plants that need the most water at the bottom of the slope, and those that need less water at the top of the slope. Because the yard is sloped, the water will drain to the bottom of the hill.
Water regularly with a hose attachment that allows you to diffuse the water to create more of a "shower" effect, rather than a direct stream from the hose. Water the top of the hill first, then work your way down. Water evenly. The plants at the bottom that need more water will receive their extra dose of water when the water from the top of the sloped garden works its way down.