Gardens do best when their soil is turned over a couple of times of year. This allows gardeners to add nutrients and minerals to the ground while aerating the soil for healthy root development. But rototilling can disturb the underground world of your garden and requires proper planning. It takes several weeks for microorganisms to reestablish themselves after upturning the soil. Spring and fall are the best times to rototill a yard for new tree planting.
Till your soil two to three weeks before planting your tree. This will allow the soil creatures and microorganisms to re-establish themselves before planting.
Measure the moisture content of the soil. Soil should be moist enough to form a ball in your hand but should break easily with pressure. Never use a rototiller in wet soil as this can damage your equipment.
Adjust the depth gauge to the appropriate depth. Large trees may need rototilling up to 1 foot deep, while smaller, younger trees need only half that. Only rototill as deep as the root ball will sit in the soil.
Rototill manure and compost into the soil. This is best done by tilling the majority of the soil and then doing one final pass to mix in the compost or manure. This will keep the nutrients from being pushed too far down into the soil to be beneficial to new trees.