Always remove rocks from the topsoil before you plant. Rocks in the topsoil may prevent small plants from developing roots and can make gardening difficult. A plant's roots will grow around rocks, and any attempt to transplant these plants can do damage to the roots as the rocks fall away. Spend a little time removing rocks from your topsoil and you can save yourself a lot of headache later.
Use a trowel or shovel to dig up any large rocks that you see protruding through the soil's surface.
Use a rototiller or shovel to till the soil to a depth of 6 to 8 inches until it is an even texture and free of clumps (the average topsoil depth and the depth to which most gardens and lawns should be tilled before planting). Pick out any large rocks that you find along the way.
Remove small rocks from the soil by sifting the topsoil through a screen. Any appropriately sized metal mesh screen will do (when purchasing a screen, consider the size of the rocks you wish to remove). Place the mesh screen over a wheelbarrow or bucket, and pour the soil over it. The rocks will remain on the top of the screen and the soil will fall through.
Replace the topsoil and rake it smooth. Fill in any gaps or dips in the soil with a commercial topsoil.