Because Kentucky had subnormal amounts and uneven distribution of rainfall during the last five to 10 years, you may be worried about your landscape plants. Having invested time and money in these plants, now you need to take protective measures to keep them alive.
Landscape plants probably suffer more from moisture-related problems than from any other cause. Because of water, plants experience feast or famine, flood or drought, air or suffocation. Plants are 70 to 90% water, which is essential for plant growth, manufacture of food, and nutrient transport.
However, too much water can be a problem. Excess water often causes a plant’s decline and death, because when water fills the soil’s pore spaces, roots can no longer get air, and they die.
Witt, Mary L.; Geneve, Robert; Hartman, John R.; Wells, Kenneth; and McNiel, Robert E., "How Dry Seasons Affect Landscape Plants" (1988). Agriculture and Natural Resources Publications. Paper 44.