Seaweed is becoming the norm

'Passion' embodies our unlimited commitment to crops, people, and technology, driving innovation across the horticulture sector. Building on the enduring importance of personal touch, GreenTech is excited to strengthen connections and unveil new initiatives designed to inspire growth and collaboration within the industry. In a series of articles, the passion within horticulture worldwide will be highlighted from different angles. This time we focus on a sustainable initiative with seaweed, from which growers worldwide can also benefit.

Kelp Blue was founded in 2019 to help restore the planet. Originally from the Netherlands, the company cultivates seaweed for multiple purposes, including sequestering large amounts of CO2 and boosting ocean biodiversity. With several hundred hectares of seaweed forests now under cultivation, things are looking up. Kelp Blue is also making waves on land. Farmers and growers on five continents are using seaweed-based bio stimulants to increase yields and reduce environmental impact.

Seaweed-based bio stimulants

A harvest that grows up to 60 cm? Not over the entire harvest period, but per day… Few growers experience that. At Kelp Blue however, they're not surprised. Their forests of Giant Kelp algae species achieve that, reaching heights – or should we say depths, since this forest is in the ocean – of up to 45 meters. The forests are located in the oceans near Alaska, New Zealand, and off the coast of Namibia. These are places where the seawater has a year-round temperature of between 8 and 10 degrees Celsius; the ideal temperature for this algae species. The algae extract carbon and nutrients from the water. Each hectare of seaweed forest captures between 16 and 25 tons of CO2 annually, which then ends up on the deep seabed. This long-term carbon storage in deeper sea layers represents a significant contribution to achieving climate goals. The algae also contain a high dose of minerals and trace elements that are beneficial for germination, root formation, and leaf growth, among other things. Seaweed-based bio stimulants ensure that plants grow faster and more vigorously and are more resistant to stress.

Positive results

Kelp Blue has been marketing a bio stimulant derived from Macrocystis under the name of StimBlue+ since 2023. The product is used in several continents and tested on a variety of crops (including barley, tomatoes, olives, almonds, and strawberries), yielding impressive results. A cucumber grower in Namibia recorded a growth between 5 and 10% higher than when using a different bio stimulant. In a 2-hectare Spanish almond orchard, the farmer recorded a yield of approximately 260 kg per hectare when not using a bio stimulant. Using any other bio stimulant, he harvested approximately 280 kg, and when he started using StimBlue+, the yield peaked at around 350 kg per hectare.

Environmentally friendly

With a permanent team of 70 employees at the Amsterdam headquarters (including R&D staff and numerous consultants who advise farmers and growers) and several hundred employees who harvest the seaweed on-site and process it further in factories, Kelp Blue has quickly helped a significant number of people find work. In these factories, the liquid bio stimulant is naturally extracted from the seaweed. A 100% natural product that is marketed with CE marking and ECO certification. The pulp left over after the process is not discarded but is used to produce environmentally friendly packaging material. It is also in high demand among cosmetics and pharmaceutical manufacturers, among others.

High ambitions

This year, Kelp Blue expects to bring approximately 3 million liters of bio stimulants to the market, but its ambitions extend even further. The target for 2026 is already 7 million liters, says Anouk Bosman. Until 2019, she worked as a marketer in the sports industry, but after a lecture, she was so captivated by the potential of seaweed that she quit her job and joined Kelp Blue. She is now responsible for marketing and communications and has a busy and intensive schedule ahead of her. Kelp Blue will further expand its activities in the Americas, Latin America, and Asia in 2026, including participation in trade fairs in Washington, D.C., Singapore (this year), in Hong Kong, California, Mexico, and Brazil in 2026.

"Seaweed is becoming the norm"

For the continued growth of Kelp Blue and StimBlue+, the company is looking for distributors as well as farmers and growers who wish to act as ambassadors for the company. A few of these people are featured on the website. Bosman: "We are convinced that seaweed is becoming the norm. Agriculture and horticulture are becoming increasingly sustainable. As a result, more and more farmers and growers are moving away from traditional chemical agents and opting for natural solutions. Our bio stimulant is a good alternative in these cases. We are also the only one cultivating seaweed on this scale, thus ensuring a stable supply. It's a process that is also highly scalable. Yes, there are suppliers who harvest kelp from the wild, but they cannot deliver consistent quality. Moreover, there are increasing restrictions on harvesting wild kelp."

A unique experience among the fish 

At Kelp Blue, they believe this last point is more than justified. And not out of self-interest, but because they care about the oceans and everything that lives there. Bosman: "In our seaweed forests, we see a tremendous increase in biodiversity. There are up to 800 different fish and animal species living there!" The marketer knows what she's talking about, having dived into such a forest herself several times. "It's almost a spiritual experience swimming among the seaweed, fish, and crabs."