Manual Smoothing

• 1). If your lawn has only a few lumpy spots, caused by the freeze-thaw cycle or by moles and groundhogs, use a shovel and garden rake to level them out.
  
  
• 2). Check for mole and groundhog tunnels running underground. Their evidence will be in the form of a winding trail of raised dirt and sod. Smooth these areas down with a rake and firm them gently with your foot.
  
  
• 3). After flattening these areas, you may find that you have low spots. Fill in with soil and smooth with a garden rake.
  
  

Mechanical Smoothing

• 1). For an overall smoothing treatment for a lumpy lawn, Richard Jauron from the Department of Horticulture at Iowa State University's Extension Service recommends aerating the soil with a mechanical aerator first. The aerator drills or punches thousands of tiny holes in the soil, allowing oxygen, water and nutrients to penetrate the soil more easily. Aeration also loosens the soil in preparation for raking.
  
  
• 2). Use a power rake to break up thatch and lumpy spots. A power rake uses sharp knives to slice through the yard's thatch and breaks down lumps and cores left by aeration. Power raking and dethatching are performed by the same machine but serve different functions. Dethatching digs deeper into your lawn than power raking and rips out excess thatch. While dethatching can be helpful as a one-time treatment for lawns with an exceptionally deep layer of thatch, power raking is a gentler method, allowing your lawn to recover and thicken more quickly.
  
  
• 3). Rake away loose debris brought up by the power rake, and smooth remaining areas by adding soil or leveling with a yard rake.
  
  

After Smoothing

• 1). Once your lawn has been smoothed, set grass seed or sod to create a root system that will hold your soil in place. Water regularly until the seed or sod is established, but be careful not to over water.
  
  
• 2). Eliminate sources of large holes, such as moles, groundhogs and armadillos. Contact your Extension agent or county trapper for information on how to safely remove these pests.
  
  
• 3). Do not eliminate worms from your yard. Although their castings can be a nuisance, worms contribute to the health of your yard through natural aeration and by enhancing the thatch decomposition process. The presence of many worm castings in your yard indicates good soil health. Use a garden rake to smooth out their castings when their numbers become intrusive.
  
  
• 4). Use an appropriate fertilizer for your lawn to help it thicken and form strong root systems.