Answer: Some potting soils are formulated specifically to meet the needs of certain plants such as improved drainage for cacti or a particular pH for say, acid lovers, or a high level of cleanliness as for seedlings. Soilless mixes (usually based on peat and vermiculite and perlite) are relatively sterile and as such reduce the risk of importing pathogens. They may also be formulated to contain specific fertilizers or special water holding polymers. In contrast, outdoor soil varies widely in both texture as well as nutrient analysis; it may also contain insects or diseases which could affect your plants. Hope this answers your question!
Q&A Library Searching Tips