Mowing of lawns should be governed by the use to which the lawn is to be put. Mowing should not be very frequent in hot weather nor very long neglected at seasons when the grass is growing rapidly. Clipping should cease before the grass stops growing in the autumn, so that a long growth may be left on the lawn over winter. A portion of the clippings should be left on a lawn to act as a mulch, especially if the grass is cut often. Enough grass leaves must be left on each plant so that it can maintain its growth, but on the other hand, growth must not be carried to the point of seed production, which, more than anything else, tends to weaken the vitality of a plant. About two inches is the height most often recommended for grass. It is best to leave mower knives set high and mow more frequently rather than to allow grass to grow high and then cut it low and thus remove too large a portion of the leaf surface of the plant, and also expose the soil to the direct rays of the sun. When a lawn becomes run down it is generally better to remake it entirely, instead of wasting money on patching. It is well to consider that if the original grass could not succeed on the soil, new grass will certainly fail.