Biostimulant product types

Biostimulants may be grouped as either ‘microbial’ or ‘non-microbial’ and can be further classified by product type.

Back to: Biostumulants: Function and efficacy

The most common product types used in the UK are summarised in the tables below.


Group: Non-microbial

Product type

Description of the product types

Seaweed extracts

Extracted from seaweed

Humic substances

Extracted from decayed plant or animal material (e.g. humic or fulvic acids)

Phosphite and other inorganic salts

Salts that do not contain carbon. Phosphite (PO3) is a commonly used inorganic salt

Chitin and chitosan derivatives

Chitin is an abundant natural polysaccharide obtained from crustaceans. Chitosan is derived from chitin


Products that reduce transpiration by plants (e.g. abscisic acid and waxes)

Protein hydrolysates and free amino acids

Protein hydrolysates are produced from animal and plant residues. Free amino acids are obtained through enzymatic breakdown of agro-industrial by-products

Note: Biostimulants derived from mammalian tissue by-products, such as pork and beef materials, might not be acceptable to customers/buyers

Complex organic materials

Broad range of products that contain material derived from the remains of organisms (e.g. plants)


Group: Microbial

Product type

Description of the product types

Plant growth promoting bacteria

Bacteria that potentially benefit plant growth (e.g. Bacillus/Rhizobia spp.)

Non-pathogenic fungi

A wide range of fungal species that have no direct pathogenic effect on plants (e.g. Trichoderma spp.)

Arbuscular mycorrhizal fungi

Common type of endomycorrhizal fungus that forms a symbiotic association with plant roots (e.g. Rhizophagus irregularis)

Protozoa and nematodes

Protozoa are single-celled rhizosphere organisms. Nematodes are non-segmented worms