Dandelions in particular, weeds in general, do not seem concerned about how long the lawn has been under good care. Airborne seed and seed which have been in the soil for years will seek the opportunity to grow in any area of weakness in turf density. In fact each dandelion weed produces up to 200 seeds per weed plant. Weather extremes usually create these kinds of weak areas, even in the best lawns.

Since different lawns develop thatch layers at different rates, the only answer available is – regularly. However, annual or bi-annual aeration in September and October (when roots are growing vigorously) will normally prevent an unpleasant mess at some future date.

Fertilization will allow the lawn to recover with the areas recovering center out giving it a “frog-eye” look. Even after disease controls are applied, a disease can be persistent.

Thatch is a mat of old root systems, partially decayed leaves and upswept clippings which accumulates between the grass plants, just above the soil surface that holds nutrients to the soil and protects the crown of the grass blade.