Harris Bonsai Soil, All Purpose Premium Blend for Outstanding Growth, 2qt Harris Bonsai Soil is expertly blended for your bonsai needs, combining a premium mix of ingredients in the correct ratio to keep your bonsai at its best. Bonsais have specific needs - and it starts with quality soil. Through the soil in the pot, the tree must be able to obtain water, nutrients and air in order to sustain life. Traditional potting soil retains too much water to allow your bonsai to thrive and grow. How often you should repot depends on timing, the size of the pot and tree species of your Bonsai. You should use care in this process to ensure successful bonsai growth.