Plant nutrient supplements, seaweed extract (KELPAK) and BIOGROW, were applied on pakchoi plants in order to alleviate waterlogged damage. When the plants were treated with 1000x diluted KELPAK or 600x diluted BIOGROW, the fresh weight loss was due to waterlogged reduced by 3.0%-33.8%. Chlorophyll depression was reduced as well. Besides, the photosynthesis rate and water content of leaves remained unchanged under waterlogged. The BIOGROW treated plants had 8.1%-16.0% more fresh weight than the untreated control. Both KELPAK and BIOGROW improved the plant growth after waterlogged.