Mowing your lawn isn't supposed to be a roller-coaster ride. Low areas in turf collect water, and we all know that too much moisture promotes fungus growth. High areas get scalped when you mow. Here's how to fix those bumps and dips in the turf.
Cut an outline around the uneven area by inserting a spade into the turf. Place your foot on the base of the spade and push into the soil 7.5 to 10 cm (3 to 4 inches). You're going to remove the turf, but first you need an outline to follow.
Slice the turf with the spade across the middle of the outlined area to make the sod more manageable. Pieces of sod should measure 45 to 60 cm (18 to 24 inches) wide.
Insert the spade under the sod and gently slice the roots as you shove the spade under the turf. You want to retain as much of the root growth as possible. This is the hardest part of the job. Sometimes those roots just don't want to let go. Try not to tear or rip the sod pieces.
Lift and roll the loosened sod as you cut away the roots.
Set the reserved sod in a shady area and keep it moist to prevent the roots from drying out.
Flatten the uneven area with a spade or shovel by adding or removing soil to match the level of the surrounding soil. Be sure to take into account the 2.5 to 5 cm (1 to 2 inches) of soil that's still attached to the sod.
Water the prepared area.
Lay down the previously removed sod onto the prepared soil. Adjust the sod's dimensions to fit the area.
Fill small cracks in the turf with more soil.
Keep the newly leveled area moist, especially the seams and most especially during hot weather.
Water the lawn normally after the sod becomes re-established.
If the uneven area is a small dip in the turf, spread 7.5 cm (3 inches) of fresh potting soil directly on top of the turf. The dip will flatten out as the grass grows through the layer of soil. In cold climates where winter freezing makes your lawn uneven, use a water-filled roller in the spring to even out affected areas.
For optimal results, avoid fixing uneven areas in hot weather. Extra water helps sod grow. Don't fertilize until you see new growth.