Nice question. In some website, they suggest that it should be at least three times a year but on my own opinion is, it depends how your lawn react to your style of taking care it. If you can see that it starts to have a yellow color then apply my technique. Use the cheapest fertilizer that is applicable for all
vegetables, just spread it around the affected area and water it for at least 1 inch deep, after two days of not watering, spread some sugar around the affected area again then water it normally. After two weeks, you can see some magic results. God Bless
You water and fertilize it
U fertilize it
Aeroate the soil, fertilize. water
You should fertilize once before winter and then another during spring.
aerate the soil, breakdown leaves and grass into compost, fertilize the soil with their droppings
Fertilizer in essense, is manure. Manure can come in all forms. Manure is used to fertilize your grass and plants so your grass and plants can grow prosperous.
You should seed, wait for the seed to germinate, and then apply your fertiliser. Some fertilisers also contain weed killer which will prevent grass seed germinating.
Up to the bearing age you should fertilize four times a year, and after bearing twice a year Cooray
You should do this the other way around ... mow it first then apply the fertilizer. Otherwise you are just putting all that fertilizer into the grass catcher of the mower.
Fertilize your soil often and keep ground moist.
Chemical changes are certainly part of what is happening.
You are going to need to fertilize you lawn. If the fertilizing is not helping, you will want to put down new grass seed.