Colins back with more GardenTips. Excessive sun exposure and cold temperatures can turn lemon tree leaves yellow. Why Are My Lemon Tree Leaves Yellow Citrus Trees Lemon Tree Fruit Garden According to Glen Wright a specialist in citrus at the University of Arizona yellowing lemon leaves can be a side effect of overwatering and trace mineral deficiencies but sunburn may also be a factor in the condition. Lemon tree leaves yellowing . So make sure to dump it out after a good long soak. This net-vein pattern occurs primarily in young leaves of the fall growth flush as soils cool reducing root activity. Meyer lemon trees are evergreen but just before the spring flush of new leaves Meyer lemons will drop old leaves. If you only have a few yellow leaves in those locations then that is natural and part of the trees normal leaf shedding process and poses no concern. Yellow Leaves Due to Lack of Nitrogen If your lemon tree shows chlorosis of the leaves that is yellowing due to lack ...