1. Soil Amendment: Seaweed can be added directly to the soil as an organic amendment. It decomposes, enriching the soil with nutrients and improving its structure, which enhances root growth and water retention.
2. Fertiliser: Seaweed extracts are commonly used as liquid fertilizers. These extracts provide plants with a quick nutrient boost, supplying essential minerals that are crucial for plant health.
3. Growth Stimulants: Seaweed contains natural growth hormones, such as cytokinins, auxins, and gibberellins, which can stimulate plant growth, enhance seed germination, increase fruit yield, and improve plant vigour.
4. Pest and Disease Resistance: The application of seaweed in horticulture has been associated with increased resistance in plants to pests and diseases. This is partly due to the improved overall health of the plants and possibly due to specific compounds in seaweed that strengthen plant defences.
5. Biostimulant: Seaweed acts as a biostimulant, enhancing the plant’s natural processes to absorb more nutrients from the soil and improve stress tolerance, such as drought or saline conditions.
6. Composting: Seaweed can be added to compost piles to accelerate the composting process and enrich the final compost with nutrients, making an excellent organic fertiliser.
7. Foliar Sprays: Seaweed extract can be applied directly to plant leaves as a foliar spray. This method is effective for quickly providing plants with a rapid boost in growth and health.
8. Root Dips: Before planting, roots of seedlings can be dipped in seaweed solutions to enhance root development and improve transplant success rates.
9. Water Retention Agent: The alginate content in seaweed can help improve soil’s water-holding capacity, benefiting plant growth in dry conditions.

Utilising seaweed in horticulture not only promotes healthier plant growth but also contributes to sustainable crop cultivation by providing an organic, renewable resource for nutrient management and plant care.