Annual Grasses

• All grasses are either perennial or annual. If the grass species is annual and the growing season has come to an end, expect the grass to die. Annual ryegrass (Lolium multiflorum) is a common example of a quick-growing turf and cover crop that dies when the weather turns cold. In the southern U.S., annual ryegrass seeds begin to germinate in autumn, starting the cycle anew. Farther north, it is too cold for the rye seeds to survive and the grass must be resown every spring.
  
  

Seasonal Dormancy

• Perennial turfgrasses are classified as either cool- or warm-weather species. The familiar tall fescue (Lolium arundinaceum) is a cool-weather lawn grass that goes dormant naturally in the heat of summer. Constant watering in the summer creates an artificial microclimate that "tricks" the fescue into staying green in the summer heat. On the other hand, zoysia (Zoysia japonica), named after the Austrian botanist Karl von Zois, is a warm-weather grass species that thrives in the heat and dry weather patterns of summer. Zoysia lawns therefore go to sleep when the seasons change and the weather turns cold. In the winter, the brown expanses of zoysia, having stopped growing for the season, look dead but are merely dormant and waiting for the return of warm weather.
  
  

Chemical

• Grasses can stop growing when herbicides are incorrectly applied. Careless application of a weed killer that contains glyphosate can result in wind-driven drifting onto nearby grasses, ornamental specimen plants or lawns, causing them to stop growing and die. Mistaking postemergent weed killers for preemergent herbicides can also result in the death of grass species. In addition, accidental spills of petroleum-based products, as well as many household cleaners and solvents, can adversely affect a grass species' ability to grow. Finally, too much nitrogen, as from overfertilizing or urinating of a pet dog or large animal, can cause grasses to stop growing for a while.
  
  

Compaction

• Constant foot or car traffic causes earth to become compacted. This compaction eventually causes grasses to cease growing and die. Deer trails, for example, can be a sign of impending death of turfgrass, as the repeated visits to your garden begin to compact the soil and affect the growth of the grass. Core aeration will helps reduce soil compaction and keep turfgrasses growing. For automobile traffic, a pervious surface material may need to be installed that supports the repeated weight of the car over the surface, permitting the grass underneath to continue to grow.