The best method to cut long grass and to keep it maintained at a lower and more desirable height over the long term is to reduce the height of the lawn in stages. Beginning with the first lawn mowing,you will only want to remove about a third of the green leaf. At the second lawn mowing, you can reduce the height a little bit more, and so the process continues until you reach the desired height you want to achieve. The gradual lowering process of the mowing height guarantees the lawn stays alive, stays healthy, and at each mowing will gradually begin looking better. As the process of lowering the height of the lawn continues, the crowns and thatch layer of the lawn will also adjust themselves and lower themselves down to their optimum height.
Fertilize, When you cut back on overgrown grass, it forces the grass to tap into its food reserves found in the roots. Its a good idea to fertilize your lawn and give it a boost when this is happening as the thatch layer is more exposed.
The best time to use this process to lower heights of lawns is during the active growing seasons for our lawns which is during the Spring, Summer and early Fall months of the year. This is important because if the lawn is not actively growing, it cannot actively be repairing itself as the lawn repair is being undertaken. So the process will not work. If you need to tackle a lawn which is overgrown and the weather is cooler, then the best option may be to keep the lawn mowed at a higher height until the next growing season arrives in the Spring.