You should improve your garden soil with organic matter every year and keep using it year after year. Fall is a good time to pile on compost, shredded leaves, even grass clippings so they can rot all winter. In spring you can dig these organic elements into the soil and then rake it level before planting. Over time adding compost and other organic matter to your raised bed will result in a soil rich in humus and able to better retain moisture and nutrients. Keep growing, Marianne Binetti