The study was aimed on the assessment of extracts from four arctic brown seaweeds (Ascophyllum nodosum, Fucus vesiculosus, Laminaria digitata and Saccharina latissimi) as stimulators of plant growth. Seaweeds were collected from the Rebalda Bay of the White Sea in August 2021. Extracts were obtained by isopropanol maceration method, then vacuum-dried at 40C and stored at -4C. Protein, polyphenols, chlorophyll, carotenoids, alginates, mannitol and polysaccharides contents of extracts were determined. Wheat and cucumber seedlings were used as test plants. Extracts from all four brown seaweeds enhanced growth, accelerated development of plants and increased chlorophyll content in leaves. Plant responses to seaweed extracts were concentration-dependent. Higher concentration of A. nodosum and F. vesiculosus extracts inhibited plant growth possibly due to higher phenolic content. The results show that investigated seaweed extracts obtained by isopropanol maceration method with subsequent drying and freezing have proven to be effective in plant growth stimulation.