Abstract: A protective horticultural bag is an apparatus that is placed over a plant growing container in order to provide a physical barrier between the root ball of the plant within the container and the exterior environment. The protective horticultural bag features a tubular membrane that is stretchable in order to accommodate various designs of plant growing containers. An elastic cord is utilized to increase or decrease the size of an open end of the tubular membrane in order to allow the stem of the plant to extend through the open end as the plant grows. A cord clamp is utilized to fix the elastic cord in place on the tubular membrane when the size of the open end is as desired. The tubular membrane is breathable in order to allow liquid and air to pass through the tubular membrane while preventing insects and other pests from accessing the plant.