You will often hear people rail against lawn grasses. They will say how they have a small root system and how they need to be fertilized and treated with horrible chemicals to keep them alive. They will say other plants don't need this amount of labor or chemicals to maintain them and thus claim the other plants are better. Most lawn grasses left to grow on their own would grow to 18 inches to 2 feet tall. If allowed to grow to their normal height, they, too, would have a big root system and need far less care. It is not the type of grass that is the problem; the problem is that we mow them all the time and plant them on bad soil.
Plants must always maintain a balance between the roots and the top. A plant can't have more roots than leaves that can supply food and it can't have more leaves than roots that can supply water.
Good soil is more important than a fertilization program. Most lawn problems start because the grass plant can't grow well due to a poor soil. If you take care of the lawn's soil, the grass plant will almost take care of itself. Conversely, without a good soil, you will have to work hard to take care of the grass plant. A lawn with poor soil will require more work to keep it growing and healthy, or else it will be sparse and full of weeds.
First, a good soil is alive. It is filled with worms, insects, microscopic animals, bacteria, fungi and other organisms. Plant roots are healthier when they are surrounded by organisms that are often killed when the fertilizers, herbicides and insecticides are applied. Applying fertilizers that are slow release and based on plant materials rather than chemical salts will be less likely to damage the soil. Applying a thin layer of compost to a lawn each spring will feed numerous organisms that in turn will supply the grass plant with the nutrients it needs.
To meet the nutrient and moisture needs of a plant, the soil must be deep enough so the roots can grow to their maximum potential. Healthy low-maintenance lawn grasses need a minimum of 6 inches of good topsoil. Very often, lawns survive on less than that amount, but it takes more maintenance by the caretaker to keep it healthy. A thin cover of lawn grasses can be kept on just an inch or two of soil, but don't expect it to handle much wear and tear from activities. If other plant roots share the soil, they compete for water and nutrients with the lawn grasses, so again, a deeper soil is better.
The last thing lawn soil must have is good drainage. Grass roots need air and water in the soil. If the pore spaces are filled with water, the roots will drown. If the soil is compacted, there are not enough pore spaces to have air or water and the roots will not be able to grow in it. Sandy soil can have too many pores and so it won't store moisture. Adding composted organic matter will benefit any soil type and help cure all of the pore space problems.