Watermelon plug matrix and method for grafted seedling by using same

The invention relates a watermelon plug matrix and a method for grafted seedling by using the same. The watermelon plug matrix comprises main materials of grass carbon, vermiculite and decomposed pig manure with a volume ratio of 6:3:1, and auxiliary materials of a 15:15:15 potassium sulfate compound fertilizer and EM bacteria with 2 kg-3 kg of the potassium sulfate compound fertilizer and 0.15-0.25 kg of the EM bacteria in every cubic meter matrix. The method comprises the steps of mixing the above materials together and stirring uniformly and adequately. The watermelon plug matrix is fast in seedling emergence, has tidy and consistent seedlings, well-developed root system of cultivated watermelon seedlings, and robust growth seedlings. The method is low in use cost, improves economic efficiency significantly; and is land conservation. The method can make graft of the watermelon become convenient, has high grafting survival rate, reduces weeds, prevents plant diseases and insect pests disseminated by the weeds, is convenient for transportation, and has high survival rate after colonization.