A method of preparing pest repellent for harvesting plants, a method of processing agricultural harvested products, a method of treating vegetable waste, a method for producing a cleansing composition for pest repellent and a cleansing composition for pest repellent are provided. The method of preparing pest repellant comprises providing plants, collecting parts of the plants, obtaining an extract from the parts of the plants, and applying the extract to the harvested plants. The method for processing agricultural harvested products comprises providing harvested agricultural products, collecting parts of the harvested agricultural products, obtaining an extract from the parts of the harvested agricultural products and applying the extract to clean the harvested agricultural products.