About a month ago we planted a row of 6 yew trees, in the back yard, about 12″ apart, and in a very shady area. We live in the High Park area of Toronto, which has a very sandy, oak savannah soil. They are about 5′ – 6′ tall, and we wanted a ready-to-go barrier between our yard and our neighbours. Also there’s a Norway maple tree, and a mulberry tree nearby. Now the needles in the middle are turning yellow, and falling off. The new growth looks healthy and green. I was told to use 30-10-10 evergreen fertilizer. I’ve been watering them every day, a pail full each, is this too much?
The coniferous Taxaceae family, commonly called yew, includes seven genera, and about 30 species of shrubs and trees. Needle drop is common, close to the trunk, and this is a natural part of the growth cycle as the plant matures. If you had reported that the new growth had started to yellow, this would be an indication that the plant is suffering from one or more varieties of stresses.
Water-wise, yews enjoy moist soils, but do not like standing in water. While your regional sandy soil should provide good drainage, the amount of daily water you’ve applied over the past month may not be draining away quickly enough to prevent the roots from suffering from a lack of oxygen. When roots can’t breathe, uptake of nutrients into the plant above the soil is at risk. So perhaps dial down a bit on the watering, and wait until the surface soil has had a chance to dry, taking into account ambient rainfall. Fertilizer-wise, young yews appreciate a nitrogen boost to promote lush growth, but do be sure to follow the amount-and-frequency application instructions to the “T” on the packaging. One last note, you may wish to consider some judicious pruning of some of the lower branches of the adjacent maple, to free up some sunlight, and to improve general air circulation around your new plantings. Thank you for calling, and all the best with your new additions to the garden.