Grade	Form	Alginic acid / alginate	K₂O	Organic matter	pH
Seaweed extract 12%	Black flake / powder	≥ 12%	10–12%	≥ 40%	8–11
Seaweed extract 14–16%	Black flake / powder	14–16%	14–16%	≥ 40%	8–11
Seaweed extract 18%	Black flake / powder	≥ 18%	≥ 18%	≥ 45%	8–11
Seaweed extract flakes 20%	Black flake / powder	≥ 20%	≥ 20%	≥ 50%	8–11
Enzymolysis seaweed powder	Green powder (Ascophyllum nodosum)	Alginate ≥ 40%	≥ 20%	≥ 60%	6.8

All grades are 100% water-soluble. Values are supply specifications; confirm them against the COA of the lot you test.

How to choose

Alginic acid level: higher-alginate grades allow lower dose rates and more concentrated finished products.
Process: the black flake grades are alkaline extracts of brown seaweed (pH 8–11); the enzymolysis powder is digested with enzymes, is near-neutral (pH 6.8) and tolerates hard water.
Use: dissolve for foliar sprays, drip irrigation or root drench, or use as a raw material in organic, biological and compound fertilizers.
Combination with carbon: seaweed extract is often formulated with humic and fulvic acids or amino acids in one liquid. Check compatibility and pH of the blend before scaling up.

Where seaweed extract fits in a fertilizer programme

Seaweed extract is not a replacement for NPK. It is a supporting input used alongside the main fertilizer programme, typically at sensitive stages such as transplanting, flowering and fruit set, or after weather stress. Growers usually apply it as a foliar spray or through drip irrigation, and formulators add it to liquid fertilizers to differentiate their products. Start with the dilution on the product page, run a side-by-side strip trial against your current programme, and keep the treatment that pays back in your own crop.

FAQ

What is seaweed extract fertilizer?

An extract of brown seaweed that supplies alginic acid, seaweed polysaccharides, potassium and other natural compounds. It is used as a biostimulant component in foliar, fertigation and organic fertilizer products.

What does the percentage (12%, 18%, 20%) mean?

It is the minimum alginic acid content. Potassium (K₂O) and organic matter rise with it, as shown in the table above.

Flake or enzymolysis powder?

Black flakes are alkaline extracts and suit most blends. The enzymolysis powder is near-neutral, high in alginate and oligosaccharides, and is chosen for premium foliar products and hard water.

How is seaweed extract packed?

In 25 kg woven or kraft bags with an inner liner; jumbo bags and private-label packing on request.