Use topsoil to even out and build up the soil before planting a lawn. Spread 4 to 6 inches of topsoil over the planting surface and use it to even high and low spots. Water the topsoil to settle it, then rake it to break up any hard spots. Seed grass over the topsoil
Amend vegetable garden plots in the spring before planting, or in the fall after you clean them out. Dig several inches of topsoil and organic compost into the natural soil to loosen and aerate it, and to add nutrition and moisture retention. This is especially important in tight, thick soils, which hold water and bind plant roots.
Add more topsoil to bare patches in the lawn in spring or summer, before reseeding. Re-amend garden soil with new topsoil and compost applications in spring to maintain soil condition, and at any new planting.