Apr 22, Overwatering – If your lemon tree is dropping leaves, another common reason may be overwatering. When roots of the tree sit in water, they have a tendency to develop root rot, which in turn results in the lemon tree dropping leaves.
Mulch around the root area, minimize irrigation, plant in well draining soil, and keep grass away from the base of the tree to avoid root rot and its. Lemon trees are moisture sensitive and will drop leaves when over- or under-watered.
Initially, leaves on drought-stressed trees curl and turn dry.
Leaves on over-watered trees flatten and droop. To establish young trees, water thoroughly three times the first week. Jan 14, If the container soil temperature is not in the range of 65F (18C), 70F (21C) is better, the roots are dormant, and cannot send moisture to the leaves to cool them. Therefore, in an effort to maintain a balance between the leaves and the roots, the tree drops it's leaves.