Fertilizers

• Most inorganic fertilizers combine nitrogen, phosphorous and potassium. The amount of each nutrient per bag is shown as a percentage: a 10-10-10 fertilizer will contain 10 percent nitrogen, 10 percent phosphorous and 10 percent potassium by weight. In lawn fertilizers, the nitrogen content is much higher.
  
  

Lawns

• Turf grass grows quickly under the right conditions. A lawn will continue to grow throughout the season, as long as temperatures permit. The rapid, season-long growth habit combined with the shallow root system increases a lawn's nutritional demands.
  
  

Shrubs

• Most woody shrubs have a definite period of new growth, usually in early to late spring. After this period, the shrub will remain roughly the same size throughout the rest of the season, and the shrub's nutritional requirements drop.
  
  

Effects

• Lawn fertilizers, when used on shrubs, encourage growth that stresses the plant. The existing root system may not support the top growth, resulting in a shrub that sprouts a flush of new leaves and then wilts. If a shrub is fertilized after midsummer, the shrub may put out new growth that will be damaged by early frost. This damage leaves the plant vulnerable to insects and disease.
  
  

Conclusion

• Lawn fertilizers have specific formulations based on the needs of turf grasses. Landscape shrubs have widely different needs than a turf grass. If necessary, a fertilizer designed for shrubs and bushes should be used early in the season.