Preparing the Soil Item Number: preparing-the-soilFor first time beds, roto-tilling is usually necessary. Till when the soil is dry. Tilling while wet will leave large, unmanageable clumps. Till the plot to a depth of 18" adding organic material as you work the soil. Humus and manure are excellent for building up the soil. Your garden should be prepared by hand in following seasons. Roto-tilling can destroy earthworm activity which is important for the garden.