Seaweed has been used as a soil improver for centuries, particularly in coastal areas. Seaweed contains several useful plant nutrients, including nitrogen, potassium, phosphate and magnesium. There are dried and liquidised forms available from garden centres and seaweed is a common additive to fertilisers, both organic and non-organic.
- Seaweed is a good source of plant nutrients
- Processed seaweed extracts are sold in dried or liquid form
- Fresh seaweed can be dug into the soil like manure
- Calcified seaweed makes the soil more alkaline
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.