What you’ll need
step 1: Get Rid of Weeds or Grass
If your new garden is an empty field or someplace else where weeds have grown freely, your first task is to get rid of the weeds. First kill the growing weeds with Roundup weed grass killer. If the weed growth is heavy, or if they are wiry and tough, remove the dead weeds with a hoe. Otherwise, just let them stay to be tilled into the soil.
If the new garden area is in turfgrass, either transplant it for use in another part of the garden, or kill it with Roundup. After killing the sod, remove it with a mattock or rented sod cutter. You can till the sod under if you wish, but chunks of turf will remain in the soil for several weeks, interfering with planting.
step 2: Solve Soil Problems
If your soil has any serious soil problems, such as being too rocky or heavy or sandy, solve them now. See here about Problem Soils for help with specific problems.
step 3: Spread Soil Amendments
Spread 2 to 3 inches of cow manure plus organic compost over the entire area. This organic matter improves any soil, from the heaviest to the sandiest. If anything else—such as lime or gypsum—is required to solve your soil problems, spread the recommended amount on top of the compost.
step 4: Mix in Amendments
Till the soil by turning it over with a shovel or rotary tiller. Work the soil to a depth of 6 inches. It isn’t necessary to work the soil into a fine powder, but just until it looks like coarse bread crumbs. After tilling, level the surface with a garden rake. Rake out any rocks and clods in the top two inches and smooth the surface to make a fine seedbed.
step 5: Germinate and Kill Weed Seeds
Keep the soil watered for a couple of weeks to germinate any weed seeds, then kill the weeds with Roundup weed & grass killer. If the soil has been growing weeds for some time, this is an important step; it may hold many pounds of weed seeds that will germinate after you have planted. By germinating them now, you get rid of the seeds. Once the weeds are killed, try not to dig too much. Disturbing the soil will bring more seeds to the surface to germinate.
If the soil has been under cultivation or has been kept free of weeds, this step is not necessary.
step 6: Plant Your Garden
Plant seeds or transplants now, knowing that you’ve given the garden the best start it can have, and have laid the foundation for years of healthy plants.