Sourced from the University of Minnesota | Agriculture Extension
Fertilizer application for new turf:
Fertilizer recommendations for establishing a turf area differs from those for an established turf. The main reason for these differences is due to the ability to include fertilizer before the turf is established.
Suitable nitrogen produces vigorous growth and green color in turf. Either too little or too much nitrogen can cause problems. Too little available nitrogen leads to slow growth, increased chance of some diseases, yellowing of plants, and thin turf resulting in increased weed pressure. Too much nitrogen leads to excessive shoot and leaf growth, reduced root growth, low carbohydrate reserves, poor tolerance of environmental stresses, and increased susceptibility to some diseases.
If the grass is established from seed, incorporate N fertilizer into the surface 1/2 to 1 inch of soil. Either rake the fertilizer into the soil along with the seed or till it in just before planting. If the grass is established from sod, N fertilizer should be applied over the sod the day after it is laid and watered in lightly. Sod is watered heavily immediately after it is laid, so it is important to delay fertilization or the N will be leached below the root zone.
Phosphorus is important in stimulating early root growth. It can move out of soils through surface runoff and erosion processes, which can result in degradation of surface water quality. Soils naturally high in phosphorus are apt to provide sufficient phosphorus for vigorous lawn growth for many years without adding fertilizers containing phosphorus. It’s also important to note that phosphorus fertilizer application may be restricted in some area due to concern about runoff, and the impact on local lakes and rivers.
Potassium deficiencies in lawns have led to increased incidence of turf diseases and reduced tolerance to environmental stress.
Where soils are high in native potassium, supplemental potassium fertilization may be unnecessary; however, where soils are low in native potassium, supplemental applications are very important. Soil tests are essential to determine the potassium level of a soil and to develop a potassium fertility program.
Fertilizer application for established turf:
The amount of nutrients required by an established turf area depends on the type of grass and the management practices.
A healthy growing watered lawn, with clippings removed often, requires more added nutrients than a lawn not watered during the summer, and with clippings are left on the turf. When developing a lawn fertilizer program, it’s key to divide turf areas into high and low-maintenance groups.
Turf characterized by heartily growing varieties, such as improved Kentucky bluegrass and improved turf-type perennial ryegrass varieties.
- For best results these lawns are watered during the summer to maintain green growth.
- Clippings may or may not be removed. Usually there is no need to remove the clippings. In fact, clippings left on the lawn gradually decompose and reduce the need for fertilizer.
- Heartily growing Turf may develop a thatch layer and require occasional aerifying or vertical mowing to control thatch.
This turf typically contains plants such as creeping red fescue, chewings fescue, hard fescue, or some of the common types of Kentucky bluegrass which grow and spread more slowly than those found in high-maintenance turf.
- Low-maintenance turfs do not receive watering frequently (other than rainfall) during the summer months, and grass growth is minimal during hot, dry periods.
- Clippings are usually left on the lawns.
There is a great deal more information available about maintenance and care of turf. We could spend an entire week just on that topic, so we will share much more to with you. Thus check out the link below for access to the your full lawn fertilization guide.