This article provides a comprehensive review of the effects of various seaweed species and seaweed products on plant growth and development, emphasizing their use in sustainable agricultural systems. Seaweeds, particularly brown algae like *Ascophyllum nodosum*, have been used as biofertilizers and soil conditioners for centuries due to their rich content of organic matter and nutrients. The benefits of seaweed extracts include promoting early seed germination, improving crop performance and yield, enhancing resistance to biotic and abiotic stresses, and extending the shelf life of perishable products. The growth-stimulating activities of seaweed products are attributed to various components such as macro- and microelement nutrients, amino acids, vitamins, cytokinins, auxins, and abscisic acid (ABA)-like substances. These components affect cellular metabolism, leading to enhanced plant growth and yield. The article also discusses the chemical components of seaweed that influence plant growth, including carbohydrates, minerals, and trace elements.This article provides a comprehensive review of the effects of various seaweed species and seaweed products on plant growth and development, emphasizing their use in sustainable agricultural systems. Seaweeds, particularly brown algae like *Ascophyllum nodosum*, have been used as biofertilizers and soil conditioners for centuries due to their rich content of organic matter and nutrients. The benefits of seaweed extracts include promoting early seed germination, improving crop performance and yield, enhancing resistance to biotic and abiotic stresses, and extending the shelf life of perishable products. The growth-stimulating activities of seaweed products are attributed to various components such as macro- and microelement nutrients, amino acids, vitamins, cytokinins, auxins, and abscisic acid (ABA)-like substances. These components affect cellular metabolism, leading to enhanced plant growth and yield. The article also discusses the chemical components of seaweed that influence plant growth, including carbohydrates, minerals, and trace elements.