Raking and Moisture Control

• Raking moss-invaded soil is a good step in removing the problem, according to the Washington State University Spokane County Extension website. Cool, moist conditions also favor moss growth, so the university also advises against overwatering, especially where moss is already present.
  
  

Aerate Soil

• Compacted soil favors moss growth because soil particles are forced together. This seals the soil surface, making air and water penetration--and drainage--difficult. Aerate soil where moss has invaded. This can be done simply by churning the soil with a spade--being careful to avoid flower roots.
  
  

Reduce Shade

• Shade favors moss growth. Remove shading objects when possible--such as patio umbrellas--and prune trees and shrubs that may be shading the flower bed. This will allow more light to penetrate the soil, which will help inhibit moss growth.