Over the years a lawn may begin to look ragged, particularly if it isn't cared appropriately.
If more than half your lawn has large worn-out or bare patches, or is rough and bumpy, consider replanting the entire area.
Strip off the existing grass with a spade, working the blade horizontal thrusts to cut through the roots.
If the lawn is extensive, it may be more convenient to rent a sod-cutting machine.
In most cases you can renovate an existing lawn, rather then starting over.
The first step is to determine the source of the problem.
Patchy, yellowed lawns are often the result of thatch build-up or soil compaction.
Thatch is a light brown layer of grass debris that builds up just over the soil surface.
Eventually it forms a dense mat that stops water and fertiliser from penetrating the soil. As a result the lawn languishes.
Compacted soil, caused from heavy traffic also keep water and oxygen from penetrating the soil, starving and suffocating the grass roots.
Cut out a three-inch section of lawn, and study the cross section.
If the thatch is more than half an inch thick or the soil is compacted, you'll need to take remedial act.
Both detaching and aerating are best done before you spread any seed, fertiliser or amendments.
There are special forks and shoes with prongs designed to break through the ground to aerate the grass.
While wearing shoes, walk around the lawn, punching holes as you step.
The forks and shoes that remove plugs are fine for a small lawn, but the most proficient and effective way to do the job on a larger lawn is to use an aerating machine.
Look for the kind that actually lifts out the cores of soil. These machines are available at outdoor equipment rental stores.
Crisscross over the lawn in various directions to thoroughly work the space.
Begin by mowing the lawn as close to the ground as possible.
Then use a detaching machine or power rake to break up the grass.
Run the machine back and forth in rows going in one direction; then repeat, covering the same territory from a different angle.
Continue passing over the area until the grass is well broken up and the soil surface is exposed between the remaining grass plants. Rake off the excess debris.
If a soil test recommends lime or sulfur to adjust soil pH, spread it over the lawn now.
Do not spread fertiliser at the same time that you spread lime, or a chemical reaction will cause the nitrogen to evaporate, wait a few weeks.
Wait until after you seed to spread topdressings of compost or aged manure. You can also plug grasses that spread through runners.
Grass is perhaps the highest-maintenance plant in any garden. It needs weekly mowing during the growing season, edging, trimming, fertilising and watering.
Nevertheless, by following a few basic principles of care routine, you can grow a beautiful and healthy lawn, even in desert conditions.