Lawns can require the greatest amounts of fertilizers and pesticides of any plant type in the yard. Keeping your lawn healthy will mean that you can reduce the need for heavy and frequent applications of these products. Mowing a lawn too often and/or keeping it too short are the most common mistakes of lawn care. Grass that has been mowed too short can`t produce sufficient nutrients to sustain root growth, and the lawn becomes more susceptible to disease or weed infestation. Only the top third of the grass blades should be removed during mowing. Mowing at any time shocks the grass plant to some extent, but it is particulary vulnerable under drought conditions, in summer heat, or when growing slowly due to cold. Under these conditions, take extra care to make sure that you do not mow too often or too low.