1 Jumbo Bag. Screened topsoil (75%) mixed with organic compost (20%) and seaweed (5%). Seaweed is a natural multi-vitamin for your garden soil with 60 trace minerals and ready to use nutrients including nitrogen, potassium, phosphate and magnesium. It also contains hormones to encourage plant growth. And unlike other conditioners, seaweed does not need to decompose before its benefits are realised.