How Much Should You Water Your Green Giant Arborvitae / Murray Cypress?
Is it possible to overwater Arborvitae? Sure, yes. But it is highly unlikely.
Overwatering hurts trees by causing root rot. For this to happen trees would typically need to be in standing water for 6 weeks plus. Standing water means something similar to putting a potted tree into a bucket of water where over 50% of the pot is covered by the water for a long period of time. In a backyard this would only happen if a tree was planted in a pond or submerged area.
Overwatered Green Giants in a low lying area of the nursery suffering from root rot, Some near perfect green leaves while most are completely dried up v, with underwatering all leaves are dying at the same rate.
What about newly planted arborvitae in heavy clay areas? Sure, yes, it is possible to over water the trees. But the heavy clay areas are really far fewer than what people perceive. Hard clay is when on a hard dirt road after a light rain even a four wheel drive vehicle can barely pass. Or when dry and even without roots and rock and auger would struggle to dig a hole. Indeed in such soil it is possible to overwater trees.
Our advice for homeowners is to water their newly planted trees daily and decrease it to 2-3 times a week as the temperatures drop in the Fall and stop as the weather turns freezing. As the trees mature the watering becomes less important for tree survival, but possibly just as important for optimum growth and beauty.
Driplines and soaker hoses connected to a timer (and covered by mulch) are often the best assurance for happy and healthy trees.