Worm Castings vs Compost: Which Is Better for Your Garden?

Wikipedia: VermicompostClemson Cooperative Extension: Worm Composting
Verdict

Worm castings are a premium soil amendment with higher microbial diversity and more plant-available nutrients per volume. Compost is cheaper and better for bulk soil improvement. Use worm castings for potting mixes, seed starting, and container plants. Use compost for amending garden beds and large-area soil building.

How Do Worm Castings and Compost Compare?

Worm Castings wins 3 of 5 categories. The breakdown below covers microbial diversity, nutrient availability, cost, bulk soil improvement, seed starting.

FactorWorm CastingsCompost
Microbial Diversity
Worm castings contain a wider range of beneficial microorganisms per gram than traditional compost
9
7
Nutrient Availability
Nutrients in worm castings are more immediately plant-available due to the vermicomposting process
8
6
Cost
Worm castings cost 5-10x more per cubic yard than bulk compost. Compost is often free from municipal sources
4
8
Bulk Soil Improvement
Compost can be applied in thick layers for major soil building. Worm castings are too expensive for bulk use
5
9
Seed Starting
Worm castings create an ideal seed-starting medium: fine texture, disease suppression, and gentle nutrition
9
6

When Should You Choose Worm Castings?

Choose Worm Castings when you prioritize microbial diversity, nutrient availability, seed starting. Worm castings contain a wider range of beneficial microorganisms per gram than traditional compost

  • Microbial Diversity: Worm castings contain a wider range of beneficial microorganisms per gram than traditional compost
  • Nutrient Availability: Nutrients in worm castings are more immediately plant-available due to the vermicomposting process
  • Seed Starting: Worm castings create an ideal seed-starting medium: fine texture, disease suppression, and gentle nutrition

Learn more about Worm Castings

When Should You Choose Compost?

Choose Compost when you prioritize cost, bulk soil improvement. Worm castings cost 5-10x more per cubic yard than bulk compost. Compost is often free from municipal sources

  • Cost: Worm castings cost 5-10x more per cubic yard than bulk compost. Compost is often free from municipal sources
  • Bulk Soil Improvement: Compost can be applied in thick layers for major soil building. Worm castings are too expensive for bulk use

Learn more about Compost

Sources

Source:Wikipedia: VermicompostSource:Clemson Cooperative Extension: Worm Composting

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