Q. I read your article in the newspaper regarding the effects on limbs from overwatering of Italian Cypress. I have 15 mature Cypress along a back wall. They are about 18 years old and 30 feet in height with 7 to 9-inch diameter trunks. They are watered 3 to 4 days a week in the summer, three cycles per day and 5 to 8 minutes per cycle. They each have three drip emitters with 10 gallons per hour. I’m afraid to change the watering cycle for fear the trees are used to more frequent watering. I just don’t know.
A. Don’t argue with success if there are no problems. If the trees are healthy and you are happy with their appearance I would not change anything. Tree roots adjust to the location and number of emitters that are used. Once you begin changing this it requires the tree to adapt to the change.
You are right. If you do change the watering pattern, do it in increments and don’t do it all at once. Do it gradually.
|Italian Cypress should grow upright without floppy branches. It helps if they are surrounded by dry soil. Dry soil "pulls" water from the wet areas and helps them to dry out faster.|
But you should be aware of several things about watering trees. First, it is best if trees are watered less often but with more water. I think a saving grace for you is that you give one day of “rest”, without water, between irrigations. This gives the soil a chance to drain and the roots a chance to “breathe”.
If soils around the roots of Italian Cypress are kept constantly wet, the tree can grow very rapidly. This is good, and this is bad. If Italian Cypress grows very rapidly then the limbs can become very long and weak. Limbs may begin to droop and not give the tree its characteristic rocket like shape.
Secondly, the roots will grow near the surface of the soil, shallow, because they can’t get a good mixture of air and water to grow deeper. The soil is too wet. This may not help the tree anchor itself in the soil during strong winds. It might blow over easier. Perhaps the saving grace in all this has been a lack of applied fertilizer. I’m not sure.
Thirdly, as trees get larger they need water applied further and further from the trunk. These additional drip emitters give the roots a chance to grow further from the trunk and provide better anchorage in the soil.
Perhaps there are other plants growing close enough, or even a lawn, where the Italian Cypress can take on water. But only three emitters per tree, watering trees of this size, does not spread the water out far enough to give them strong support to keep them upright in strong winds.