What Is Air Fern?

You May Have Heard Of It, But What Is Air Fern, And Where Does It Come From?

Air fern (sometimes called sea fern) adds colour and texture to terrariums, ‘moss’ walls, displays, installations and arrangements. Its fluffy little fronds look like the ferns you might spot in woodland, yet air fern isn't a fern at all.

We're lucky to work with a wonderful UK business that has harvested this product for many years, and their skill in processing it into something florists and designers can use is second to none. James Elbra and his family, of Thames Products, have fished the waters around the east of England for decades. They do the environment a real service too, because they pull out a lot of plastic waste along with the sea fern. Keep reading to find out more.

Key Facts About Air Fern

• Scientific Name: Sertularia Argentea.
• The skeleton of a tiny sea animal, rather than a plant!
• Only found in certain waters around the UK, North Western Europe, and North America.
• Although very popular in the 1970s, it originally became a sought-after product in the early 20th Century.
• Natural preservatives, colours, and scents are used to keep the product and make it look more attractive after it’s been harvested.
• Perfect for adding texture to foliage walls, floral displays, and terrarium-style decorative pieces.

Sertularia Argentea

The official name for air fern is quite a mouthful, and it covers several sea creatures. That’s right, air fern comes from an animal! Sertularia are a type of Hydrozoa, which are small predators related to jellyfish. The air fern, as we know it, is the skeletal remains of this hydroid.

You may also know this as Sea fern, Aqua fern, Sea moss, Neptunus plant, and Cypress moss. These ‘air’ fern aren’t to be confused with air plants, which are quite different, living plants.

Where Is Air Fern Found?

Air fern can be found growing around much of the perimeter of the UK coastal zone. It is also found around the northeastern coastal regions of the USA and Canada.

Specific growth areas are shallow pools on sand and mudflats, and sandy substrata; usually on pebbles, shells, rocks, or other hard surfaces. Occasionally, it’s found on algal stems. It prefers areas subject to strong water movement, either from tidal streams or wave action and is abundant in narrows and rapids with tidal streams of more than three knots. Sertularia argentea is less common in silty, brackish localities.

Official records show that fern was first acknowledged as a harvested product from the early 20th Century, in regions of the German Wadden Sea. Described as ‘Whiteweed’, the harvests were carried out as a trawl to supplement the income of shrimp fishermen. Due to increased demand for the product, it was eventually regulated to prevent damage to the reproductive cycles of the Sertularia Argentea, and the beds that contained them. Licences were issued to those wishing to carry out the practice, and eventually, specialist trawling equipment was devised to make it more efficient and less damaging to the environment.

Nestled along the coasts of the Netherlands, Germany, and Denmark lies a breathtaking marvel of nature, the Wadden Sea. It stands as the largest unbroken system of intertidal sand and mud flats globally, encompassing the Dutch Wadden Sea Conservation Area, the German Wadden Sea National Parks of Lower Saxony and Schleswig-Holstein, and a significant portion of the Danish Wadden Sea maritime conservation area. | Sourced from UNESCO. Image credit Ko Hon Chiu Vincent

The product we stock is found in areas of the Thames Estuary, and the company we work with has been harvesting the product whilst going about their main work, fishing, for decades. During the 1980s and 90s, trawling the Thames for sea fern was a very competitive industry. Up to 40 trawlers would head out in all weathers to trawl for fern instead of fish. As the 90s passed, a combination of factors ended the bustling trade. With poor growing seasons affecting harvest volumes, and adverse foreign exchange rates crippling returns, the practice dwindled. Fishing resumed and very few people bothered with the fern any longer.

Harvesting and Processing Air Fern

Despite the frenzied race to harvest sea fern ending in the 90s, there is still some demand within the floristry industry. It is often used to imitate terrestrial ferns and displayed in pots, or added to terrariums or wall displays where a swathe of natural greenery is sought. It is rarely sold in its natural colour, rather dyed to different shades of green, orange and red.

When Is Air Fern Harvested?

Harvesting sea fern occurs between October and April, but it is an aside to fishing. Our suppliers describe their methods:

“The ebbing tide takes out the boats to the fishing grounds, and after approximately 8 hours, we return. Fern grows in the same places yearly and is in the exact spot my grandfather harvested it 70 years ago!

Primarily, the fern grows on a sandy seabed, as it prefers the action of the current and movement within the water. It can be found at depths of 10 to 100 feet (3–30m). Fishing gear is used to trawl for the fern and once it’s been retrieved, it is bagged up.

Helping The Environment

As part of the process, we also clear a lot of plastic waste, which is frequently caught up within it. During an average trip, we remove over 100 pieces of plastic from the estuary, including bags and helium balloons. This is a major issue for waterways and oceans worldwide, and although we are only doing a small part to help, we consider it an important part of the work.”

Examples of plastic removed from the Thames estuary during sea fern harvesting.

“ Once landed, the sea fern requires a lot of cleaning due to the large amounts of sand it contains. We estimate that for every 5kg of sea fern harvested, the processed weight is 1kg!”

Left: Unprocessed sea fern laden with sand. Right: Processed sea fern with the sand removed.

Preserving Sea Fern

“As pretty as the cleaned fern is, we further process the product to preserve it, add colour, and if required, fragrance. If these additives were not used, the fern would dry out, become brittle, and look unsightly.

The product is sold in two forms; loose and bunched. Loose product is coloured, preserved, and packed once completed.

Loose, boxed sea fern that has been preserved and coloured green.

“The bunched product takes a lot more work, as small amounts of fern have to be carefully arranged into bunches and tied before they are coloured and preserved. These are then carefully packed for shipping.”

The finished product in a simple vase, though you can use it in plenty of other ways.

As you can see, there’s a lot more to the production of air (sea) fern than you may have realised. As it is not cultivated (or indeed farmed) for commercial purposes, the harvesting of sea fern for use in floristry and interior decor is an add-on to the fishing industry in areas where it is found in nature. It is a labour-intensive process, and it helps the environment by removing waste plastics from the sea and river beds. The result is an attractive, versatile product that proves very popular with florists, interior decorators and designers. You'll find our British air fern bunches, preserved and coloured in several shades, in our preserved fillers and foliage range.

What Can I Use Sea Fern For?

After all this hard work and processing, you may wonder what you can do with air fern. It can be a complete ‘plant’ as in the image above, where individual fronds are collected into a bunch and formed to construct the effect of a fern, but we believe you could make so much more of it.

Some experiments in our studio have revealed some more quirky results and a grounded earthy combo.

It really is a product that could be used in so many ways, from resin art to wall art, so don’t be afraid to be bold and experiment! Try mixing it with other preserved flowers and foliage in terrariums and wall pieces.