I have a row of clipped cone yews facing north that I planted a couple of years ago when I installed a new garden. They are about a foot or so away from a fence. On the other side of the fence, my neighbours have mature maple, cedar, spruce and white pine. When the garden was installed, I had the soil heavily amended with compost and mulched. I have since added more compost each spring. I also have an irrigation system that waters at root level.
My problem is that the back side of the yews have died. I do have a dog which could be part of the problem, but it is all along the one side of all these yews which leads me to think that there might be something else exasperating the problem? I have had to remove a couple of them which is disappointing as everything else in the garden is thriving. Do you have any suggestions of what I could do to help these ailing yews? I read an earlier post of watering them after the dog has peed to dilute the effects of the urine.
Hello and thank you for contacting the Toronto Master Gardeners with your inquiry on your problems with Yews.
First congratulations on doing such a thorough preparation and also your recognition of the environmental surroundings.
The fact that the back sides of the yews are failing suggests that there is not enough light. Although, usually when there is light deprivation, the affected area will typically slowly just thin out then loose needles, rather than suddenly turn brown. If there is root damage, then the latter symptoms would more likely be exhibited.
The light exposure requirements of the Clipped Cone Japanese Yew (Taxus Cuspidata ‘Capitata’) range from sun to part shade, although some nurseries will rate it for full shade. While this yew will thrive in part sun , how well it does in full shade is questionable, in that they tend to get leggy and thin out depending on the how deep the shade may be. It sounds like if you are planted on the north side of a wood fence, there not be enough light filtering through. If you believe light exposure is the problem, then I would look into any opportunity to open up more light if that is practical. This could include opening up any overhanging canopy by pruning , or if your fence is a solid fencing, possibly replacing with a material which allows for some filtered light to come through.
Clipped Cone Japanese Yews do best in sandy, loam soils which are well drained , but do not like to get dried out. It sounds like you did a nice job on your soil preparation and maintenance, but just make sure your irrigation is not kept too soggy. I would discount this as your problem given that the die-back is specific on the back fence side.
References:
Missouri Botanical Gardens Yew Problems
Best of luck with your yews.