My wife & I recently purchased a house who's owner was a bit frail & had let the backyard go for a while. It's a mix of some grass, empty patches & lots of clover.
We'd like it to be a simple green lawn. Pulling it all out & putting down new sod seems like overkill. Are there other ways we could go about it?
If it makes any difference, we're in southern California.
Clover is generally an indicator that the soil is lacking nitrogen. Clover can pull nitrogen from the air and add it to the soil. If you use a "weed killing" fertilizer, it will kill the clover and you will have to buy bags of nitrogen-containing fertilizer to feed the grass. There's nothing wrong with clover in your lawn -- it makes a nice ground cover. (I make sure that seed mix I buy has clover as a component.)
The first thing I would do is get a soil test. Depending on what they check, they can confirm your nitrogen deficiency as well as other soil nutrients and pH that might be out of balance. Add amendments as recommended by the test results. Avoid the "weed and feed" fertilizers.
Then overseed with a warm season lawn seed mix mid-spring. (Follow advice in that link for best results.) You'll want to water after seeding so that the new plants can germinate and get established.
Make sure you set your mower height properly -- you don't want to cut it too short or it will harm the grass.
Make sure you water appropriately.
Depending on the results from your soil test, you may need to do a new soil test annually for a couple of years. And you'll need to consider how often you need to fertilize and what methods you want to use.
Adding to @bstpierre's excellent answer, if you simply water and mow (at the right hight, you will find that the lawn comes back pretty quickly. Adding seed can help but grass can spread into bare patches pretty fast. In general, the best thing to do is to let the clover work. It can be an important part of a healthy lawn and it will save you a lot of headache if you leave it in.
Of course this depends on how big the patches of dead space are. If they are small (say, no larger than 6 ft across by the smallest dimension) I would just say water, possibly fertilize, and just mow. You may get some initial weeds but those will get quickly selected against by the mowing and the grass runners (annuals rarely if ever outcompete perennials if everything else is ok).
Dead spots are usually an indicator of a lack of water, and the live grass roots may go further there than you expect anyway.
There is a repoblating lawn that people use it to "patch" the lawn when it has a some empty spaces. But I would prefer redoing it again, mainly to kill all the weeds. If you can send us a picture of garden to see how it looks like and give you a better advice. Good Luck
