Seaweed extract explained

Since arriving on the gardening scene, seaweed extracts have had a huge impact on the way we garden and think about soil and plant health. Raw concentrated seaweed products are available in liquid or powdered form, which are then either diluted or dissolved to form a solution that’s suitable for application.

While they offer many benefits to plants, there is sometimes a misunderstanding that seaweed extracts are the same as all-purpose fertilisers, and that using them solely will provide plants with all the nutrients they need. Seaweed products do contain a range of nutrients and trace elements, but they are typically low in phosphorus and nitrogen, two of the most important nutrients required for healthy plant growth.

The true power of seaweed extract is in the growth-regulating hormones they contain – auxins, cytokinins and gibberellins, which stimulate root development and improve resistance to stressors such as heat, drought and disease. They also contain alginates (and other beneficial compounds) that improve soil life and structure. That’s why seaweed products are often referred to as plant and soil tonics.

If your soil is fertile and rich in essential plant nutrients, you’ll see the benefits of using seaweed products on their own. However, if your soil is lacking fertility, you’ll need to use seaweed in combination with other products to boost the available nutrients. This could be a general-purpose synthetic plant food or an organic fertiliser such as pelletised poultry manure or blood and bone. You could also combine a liquid product such as fish emulsion with your seaweed extract, then apply them at the same time. Some products contain a ready mix of seaweed, fish emulsion and liquid composts and manures.

For optimal results, remember that seaweed products need to be applied regularly, like clockwork, every 2–4 weeks. Mix the product according to the packet directions, and apply it over the foliage and around the root system of your plants.

Photos by Photography by Natsky