Garden Plants

• Some exotic plants escape the home gardens where they have been deliberately planted, either through seed dispersal by plants or natural elements. As a result, they create adjacent areas of heavy concentrations of exotic plants.
  
  

Human Disturbance

• Exotic plants are opportunistic and take advantage of land that has been disturbed by human activity, thus giving it a foothold to take over an area.
  
  

Natural Disturbance

• Native plants may require fire or herbivore grazing to sustain the habitat, the absence of which can allow exotic plants to gain hold.
  
  

Intentional Planting

• In some cases, exotic plants may intentionally be planted for other uses, such as erosion control. An unfortunate side effect is that they end up invading adjacent habitat.
  
  

Soil Chemistry

• Other factors, such as soil pollution, may have altered the soil chemistry so that native plants cannot live, thus providing a welcoming habitat for exotic plants.