Sometimes, though, circumstances delay planting and the ground freezes in the winter. Plant the tulip bulbs as soon as the ground thaws in the spring, even if new growth has already started. Dig the soil up to a depth of 12 inches. Remove weeds and rocks. Break up soil clumps and loosen the soil. Spread 1 inch of peat moss on top of the planting area. Work this into the soil to the depth of 12 inches.