What is the primary drawback of using composted garbage as a substrate?

The primary drawback of using composted garbage as a substrate lies in the fact that it is not commonly employed for this purpose. While compost has benefits and can improve soil structure and provide nutrients, composted garbage can introduce various challenges that limit its acceptance and usage.

Composted garbage may have inconsistent quality, leading to concerns about its composition and available nutrients. Additionally, it might harbor pathogens or contaminants from non-organic waste, which can be detrimental to plant health. This hesitance in widespread use stems from the potential variability in the materials used, making it less reliable compared to other established substrates.

The other options, while valid concerns related to composted organic materials, do not fundamentally address the reason for its limited adoption in professional greenhouse settings. Cost may vary greatly based on location and sourcing, weed seeds might not be a problem if properly managed, and rapid decomposition is typically a management challenge rather than a limiting factor for all substrates. Therefore, the lack of common usage underlines the general reluctance to utilize composted garbage as a reliable substrate in greenhouse management.