Sugar kelp

Sugar kelp

Sugar kelp ©Keith Hiscock

Sugar kelp

Scientific name: Saccharina latissima
Sugar kelp is the crinkly belt like kelp that can often be found in deep rockpools on the lower shore or washed up on the beach after rough seas.

Species information


Length: up to 5m Frond width: over 15cm

Conservation status


When to see

January to December


Sugar kelp is a common kelp seaweed found in shallow seas around our coasts. It grows attached to rocky seabeds using root-like holdfasts. It grows at depths up to 30m and are found mainly on sheltered shores, including in deep rockpools. Unlike other kelp seaweeds, Sugar kelp has one long ribbon like frond on a short thin stipe (like a stem). This long, wide frond is crinkled throughout and gives the seaweed its other name of Sea belt. The short stipe is very flexible so that it bends and keeps the frond submerged in shallow water to prevent it from drying out on low tides. Sugar kelp grows particularly quickly in early spring and gets its name from the sweet white powder (mannitol) that comes to the surface as the seaweed dries.

How to identify

Sugar kelp is a large 'kelp' seaweed, dark browny-green, with a single broad frond that has a distinctive crinkly and wavy edge.


Common on rocky shores all around our coasts.

Did you know?

Sugar kelp was once used to give a weather forecast! Dried fronds would be hung outside and used to predict the weather using the air humidity. If the frond stayed dry, the day would be fine; if it softened and went limp, rain was on the way. This gives it another common name of Poor Man's Weather Glass!

How people can help

Seaweeds provide a vital link in the food chain for many of our rarer species. Our seas and coastline are in need of protection if we are to keep our marine wildlife healthy. The Wildlife Trusts are working with fishermen, researchers, politicians and local people towards a vision of 'Living Seas', where marine wildlife thrives. Do your bit for our Living Seas by supporting your local Wildlife Trust or checking out our Action pages.