Crushed oyster shells can be a valuable addition to outdoor plant box soil, offering numerous benefits for your plants. These shells are rich in calcium, which helps regulate soil pH and promotes strong cell wall development in plants. They also improve soil drainage and aeration, preventing compaction and root rot.

To use crushed oyster shells effectively, mix them into the top layer of your plant box soil or sprinkle them as a mulch. They break down slowly, providing long-term nutrient release. However, avoid overuse, as excessive calcium can disrupt nutrient uptake.

Ideal for vegetables like tomatoes and peppers, oyster shells are a sustainable, organic alternative to chemical fertilizers. Always ensure the shells are finely crushed to avoid sharp edges that could harm roots. With proper application, they can enhance your garden's health and productivity.