Last summer’s drought continued through most of the winter.  Lake Michigan dropped to 2 inches under its previous lowest level ever, a full 12 inches less than normal.  The drought and the lack of snow early this winter might still be reason for concern for homeowners and lawn and tree care professionals alike.  Lawns were damaged or destroyed in record numbers last season, and now we are very worried about the trees, since tree damage sustained last summer will start showing up this season.

When a tree is exposed to extended drought conditions, root development is reduced and the tree is no longer able to produce new growth.  This reduces its photosynthetic ability and food storage can be depleted.  Wound healing is also restricted, leaving the tree open to invasion from insects and disease.  Homeowners typically water their lawns not their landscapes, but very little moisture is available to the tree because the grass roots out-compete tree roots.  Proper watering practices are essential for maintaining tree health.

What does drought stress look like on my trees?

Tree leaves turn brown from the outside edges inward and in between the leaf veins.  Called Scorch, this symptom occurs because these areas naturally have the least amount of moisture.  Leaves may also appear curled or distorted.  Evergreen needles will begin browning at the tip, moving down toward the branch.  Long-term effects include branch die back and canopy thinning.  Severely affected trees may not show serious signs of decline for a few years.

How should I water?

Trees should be watered every two weeks.  There are three techniques recommended for watering with a hose.  The first method involves placing a soaker hose around the base of the trunk at least 1-2 feet from trunk.  Turn water on when leaving for work and turn it off when you return.

The second method is to turn your hose on to a trickle.  Visually divide the area around tree into 4 sections.  Place hose 2-3 feet from trunk in one section and leave running for about 2 hours then move the hose to another section until all four quadrants have been watered.

If finding time to water is an issue you may want to consider our final method using more water pressure.  First determine how much water is needed.  A general rule of thumb is 10 gallons of water per 1 inch of trunk diameter.  Measure tree at knee height to determine size.  Using medium pressure it will take about 5 minutes to produce 10 gallons of water.  To determine total watering time use this formula:  Tree diameter x 5 minutes = Total watering time.  For example, a 4-inch diameter tree should receive 40 gallons of water over 20 minutes.

Keep in mind, even established trees need to be watered in a drought but new plantings (planted within 2-3 years) are the most at risk.  Mulching with organic mulch such as wood chips can help retain moisture longer and keep the root zone cool. Make sure all newly planted trees and shrubs are mulched at a depth of 2-4 inches.  Avoid using inorganic mulches like stones or lava rocks as these can conduct heat and dry out tree roots.

Let’s not forget the grass…

As mentioned above, many lawns suffered last season.  This was especially the case for lawns that were allowed to go dormant.  Unfortunately, many of those lawns eventually died.  After about 45 days with little or no rain, many lawns will be severely damaged or die.  If we have another difficult summer, despite all the rain we have received this spring, you will need to water your lawn at least once per week, putting down 1-1.5” of water, especially during the months of July and August.  How many times you water in a week is less important than how much you put down.  We have found the best rain gauge is an old tuna fish can.  Put it out in the yard when you water and when you have 1-1.5” of water in it, you are finished.

A healthy lawn and trees add substantial value to your property and are very expensive to replace.  The money invested in watering is minimal by comparison, so be sure to water your landscape this season!  If you have any further questions please give us a call at 847.392.7097.  For more information, check out the Emerald Lawn Care site!