I accidentally watered my Italian cypresse for 7 hours using my dripping system about 20 days ago. Will this overwater damage the root? I planted them at end of February and started to water them 1.5 hours per week (except that 7 hours mistake)in May. They are 10-12 feet tall when I planted them. For the last couple of day, I noticed there are more and more limb are falling done. What should I do for the falling limbs? The weather is hot for the last two week. I am not sure the falling limb are caused by over watering or less watering, should I keep watering them?please advice
Italian cypress is a tall, columnar conifer. It likes full sun, and requires very well-drained soil. Water should absorb into the soil fairly quickly; avoiding excess watering is very important to the health of the trees. Since you planted it in February the trees will be undergoing transplant adjustments for at least the first year. The roots have to grow and adapt to the environment.
Italian cypress are very sensitive to root collar disorders. At the base of the tree the trunk flares just above the soil. This area must be above the soil for the tree to do well. Checking your trees for the flare would be a good idea. You could raise the trees since they're fairly newly planted, and over time they will do much better.
One overwatering incident will not compromise your trees. Your method of consistent watering is very good, especially until they have adapted to their new home. We're entering our summer drought period, so you may need to increase the watering frequency when we have prolonged heat. maybe to every 5 days. A 2" layer of mulch will moderate soil temperatures and reduce surface evaporation. You can check the moisture of the soil with your finger, or insert a screwdriver and note how easy it is to do that. This article has additional information, Plant health care recommendations for Italian Cypress http://www.bartlett.com/resources/italian-cypress-care-recommendations.pdf.
As for the drooping limbs, the cause may be overwatering. Your watering program sounds good, but you might want to monitor the soil moisture after watering and again when it's time to water again. It's important to get water into the root system, then allow it to drain which pulls air into the soil with the oxygen the roots also need.
You can also use a soil moisture probe to determine dryness/wetness of your soil. Check reviews of the probes, because they don't all work consistently. That will help you see how moist your soil is.
Keep mulch away from the flare and the trunk of the trees. Tree trunks need oxygen to perform properly. Use a donut shape for the application of mulch.
Thank you very much for your detailed reply. I will follow your instruction and send you report on my trees