Abstract: A vacuum blower-type mobile unit for shredding leaves and other garden debris. The unit comprises a pair of coaxially disposed rotors operated at respectively different speeds, the blades of the two rotors being separated by a minimum practical axial clearance to provide shredding action. Shredding is further enhanced by stationary radial blades fixed to the casing adjacent the input to the slow speed rotor, and a circular plate formed to include a large number of exit guide vanes including fixed blades disposed adjacent the output from the high speed rotor. The speed differential between the rotors and the shapes of the blades cooperate to create between them a high velocity axial stream of air and debris which moves smoothly through the machine, depositing the product in comminuted form in a bag or other container.