Newly planted trees – those that have been in the ground less than two years – require 25 gallons of water, approximately 1.5 inches of rainfall, per week to survive. (We like to call this “25 to Stay Alive”!) During extended periods of little or no rainfall and/or high temperatures, trees need your help.
It is important to check the moisture level on newly planted trees for at least one full year, or until the root system is established. To accurately do this, pull back the mulch and feel the soil with your hands along side the rootball about four inches below ground level. During the hot and dry summer months, this should be done every 2-3 days for smaller plants and every 3-5 days for larger plants and trees. If the soil is dry – water thoroughly; if it is moist – do not water and check the soil in another few days.
The object of watering is to find that “happy medium” neither too wet, nor too dry. Be aware that both too little water and too much water can be detrimental.
Deep watering to a depth of 12” inches below the soil surface is recommended. Saturate the soil around the tree within the “dripline” (the outer edges of the tree’s branches) to disperse water down toward the roots.
The objective is to water slowly, dispersing the flow of water to get the water deep down to the trees roots. Wateringfor short periods of time only encourages shallow rooting which can lead to more drought damage. Don’t dig holes in the ground in an effort to water deeply. This dries out roots even more. A soil needle/deep root feeder attached to a hose is acceptable to insert into the ground if your soil is not too hard and compact.
Overhead spraying of tree leaves is inefficient and should be avoided during drought conditions. Watering at ground level, rather than spraying water into the air, is more efficient.
During the drought, trees must be given top watering priority over your lawn. However, caring for trees requires different watering methods than your lawn. During water restrictions, irrigation systems designed to water turf do not sufficiently water your trees. During the drought, trees should be given a higher priority than lawns. Lawns can be replaced in a matter of months whereas a 20 year old tree will take 20 years to replace.
How much water your tree should receive depends upon the tree size. A general rule of thumb is to use approximately 10 gallons of water per inch of trunk diameter for each watering. Measure trunk diameter at knee height. General formula: Tree Diameter x 5 minutes = Total Watering Time.
Example: When you hand water using a hose at medium pressure, it will take approximately 5 minutes to produce 10 gallons of water. If you have a 4” diameter tree, it should receive 40 gallons of water – multiply by 5 minutes to equal total watering time of 20 minutes.
Garden Hose - Garden hoses can be turned on at a slow trickle and set on a root ball of a tree. During hot and dry weather you can water a tree with a trunk that is 2 1/2″ in diameter for approximately a half hour moving the hose around the tree. Hoses are ideal for watering a single plant or tree or a number of plants.
Sprinklers - Sprinklers are best for watering lawns or an entire bed of plants, especially those with annuals and perennials. They are not, however, the best way to water individual plants because they do not allow for deep watering.
Soaker Hoses - Soaker hoses are great for slow, deep watering. They can be used in beds or rows, around root balls and surrounding soil. Soaker hoses ‘sweat’ and can be left to run for several hours depending on the size of the tree or plant.
Watering Wands - They are great for providing supplemental watering, especially for container grown plants. Container plants dry out more quickly than other plants. Let the water soak through the container for a few minutes while you move on to the next plant you are watering. Then go back and water each container again with the wand to ensure the roots absorbed the water.
Gator Bags - These can be used to water trees during hot and dry summer months. They can hold up to 20 gallons of water, are secured to the trunk of the tree and will release water slowly to the root ball over the course of 15-20 hours. A convenient method of watering newly installed trees.
Other Water-Wise Tips - Container plants dry out quicker than balled and burlapped plants.
It is very important to water trees and shrubs thoroughly as needed during the hot summer months and in the late fall before the onset of winter.
Summer thunderstorms can provide some helpful moisture, BUT should not be considered a substitute for deep watering for trees.
Wilted leaves can result from the soil being either too dry or too wet thus it is best to feel the soil to determine which is the case before you water.