Troubleshooting
Northern Japanese Hemlock problems — and how to fix them
Northern Japanese Hemlock (Tsuga diversifolia) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Woolly adelgid
Hemlock woolly adelgid (Adelges tsugae) can infest needles, leaving white woolly masses at needle bases; treat with horticultural oil or systemic insecticide in early spring.
Drought stress
Needle browning and drop occur in dry, hot summers. Ensure deep watering and mulching; avoid planting in exposed, wind-swept positions.
Root rot
Phytophthora root rot develops in waterlogged soil. Ensure excellent drainage and never allow water to stand around the base.
Prevent northern japanese hemlock problems before they start
Most northern japanese hemlock issues are care-mismatch, not bad luck. Dial in the basics:
Northern Japanese Hemlock problems — FAQ
Why is my northern japanese hemlock woolly adelgid?
Hemlock woolly adelgid (Adelges tsugae) can infest needles, leaving white woolly masses at needle bases; treat with horticultural oil or systemic insecticide in early spring.
Why is my northern japanese hemlock drought stress?
Needle browning and drop occur in dry, hot summers. Ensure deep watering and mulching; avoid planting in exposed, wind-swept positions.
Why is my northern japanese hemlock root rot?
Phytophthora root rot develops in waterlogged soil. Ensure excellent drainage and never allow water to stand around the base.