Old Cypress Trees Look Sick – Dying?

Question

We have old Cypress trees and they were doing fine. In the past few years they seem to be doing poorly. There is no visible signs of disease (but I’m no expert). I wonder if they just haven’t been getting enough water, but I don’t know whether the degradation that I see is due to lack of water or not. The Oleanders that have been planted in between them have been getting bigger with thicker trunks, so I wonder if they may be stealing moisture to the detriment of the Cypresses. But our watering system is piped to each Cypress and has a soaker hose wrapped around the trunk of the Cypress so that the water drips directly around the base of the Cypress and doesn’t spread onto the oleanders. I’m wondering if they need any minerals or fertilizer or hormone. Any thoughts appreciated.

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Answer 1

The water will, probably, not be the issue. What will be an issue are the roots of the Oleander.

Likely, they are choking out your cypress. This will mean that they are competing for space and nutrients. You can feed once or twice per year to negate nutrient battles, but root space will still be a factor.

If feeding doesn't help the symptoms improve, then it may be necessary to remove one or the other species.

Another thing to consider is the short lifespan of this tree. If it is approaching 10-20 years of age, then this can be expected.

Here are some articles for each plant's care: https://www.gardeningknowhow.com/ornamental/trees/leyland-cypress/growing-leyland-cypress-trees.htm

https://www.gardeningknowhow.com/ornamental/shrubs/oleander/oleander-growing-tips.htm