Plant Roots Prefer Water and Nutrients Applied to the Same Place

Q. I have read that plants grow better with water delivered to their roots, at the same spot, over and over again. Is this true?

Eggplant growing with drip irrigation in a raised bed without sidewalls.

A. Yes, it’s true but you probably won’t notice the difference. Why? Unless you compare plants growing with water applied to the same spot, over and over, with plants watered at different places you wont see much difference. 

            Plant roots get used to the amount of water and air when water is delivered to the same spots and depth, over and over. That is one reason why drip irrigation, along with the proper spacing of emitters, is so successful as long as the plant “wets its roots” to the appropriate depth each time. Watering with a hose will not as consistent.

            Water should wet the roots to the same depth every time. Small shrubs need to wet their roots to a depth of 12 to 18 inches, medium sized trees and shrubs 18 to 24 inches deep, and tall trees or shrubs should have wetted roots to a depth of 36 inches deep. This water should be applied to at least half the area under the plant’s canopy. Obviously then large plants need more water applied to them, and this water applied to a larger area, than the smaller plants.