- Lack of water. This is the first thing to check if you have dry patches on the lawn, as a lack of water is the most likely cause. Push a spade down into the soil and move it back and forward so that you can see if the soil is dry. If you have a sprinkler system, turn it on and check that all the sprays are working and that the lawn is getting well watered. Adjust the direction if necessary to ensure adequate coverage of the dry spot.
- Lawn diseases. If there are birds pecking at your lawn, then it may be infested with some kind of pest; try to find out what and then treat it appropriately. Fairy rings are circles of mushrooms that kill the grass around them, and various other fungi can also cause dead spots.
- Over-fertilization. Many homeowners in the US add far more fertilizer to their lawns than is necessary. Not only is this wasteful and a significant contributor to storm runoff, but it can also be a likely cause of dead spots. You might even be using the wrong fertilizer for your soil’s needs, in which case a soil test may be in order to help determine the appropriate fertilizer for you.
- Other possibilities. Dog urine can also kill your grass - you know this is the cause when the brown patches have bright green edges. Scalping is another cause that occurs when too much of the grass leaves are removed during mowing (you never want to remove more than a third of the grass blade’s length at once) and lack of sunlight can also kill off spots on the lawn.
So how can you treat the bare spot?
Once you've determined the cause of a bare patch, you can start remedy it by nipping the cause in the bud. If the patch was caused by any sort of chemical spill or by dog urine, flush the area well with water and remove all the damaged grass. Next I recommend spreading compost in the hole. Then proceed to add new seed or lay new sod. If you are planting seeds, water them well and cover lightly with straw to warm and protect the seeds; with a new piece of turf (sod), cut it to fit and make sure you have dug down enough so that it is level with the rest of the lawn. Water well and do not walk on it.
Repairing the brown or dead patches of a lawn is not a difficult job. All it takes is a little bit of analysis and troubleshooting. And after you repair the spot with new seed or sod, be sure to apply plenty of water until it is actively growing – then you can water the usual amount once again.