Sometimes plastic may not allow enough water to reach the roots, stressing the tree for moisture. To avoid crown rot, keep the mulch away from the trunk. Lawn Competition When planting trees in lawn, keep the grass 15 inches from the trunk for the first three years. Competition from turfgrass stunts tree growth, and even additional fertilizer and water will not overcome this effect. A bare area around the trunk also helps prevent injury to the tree from a mower or string trimmer.
Trunk wounds to a young tree can have a severe dwarfing effect.