Crabgrass is taking over my lawn. What is the safest organic method of eliminating it without the use of harmful chemicals?

If organic fertilizer is done correctly, you will see a significant difference in your lawn as it will go a long way in resisting the crabgrass. Be sure to water your lawn well, specifically in areas that are hot and compacted, alongside driveways and sidewalks; because those areas are crucial to your lawns health.