Canadian hemlock needles turning yellow color what can I do thank you in advance
Yellowing can be a sign that the plants' roots are not in well drained soil. Can also be a sign of higher than normal ph levels (conifers are acid-loving plants - low ph).
Canadian Hemlock are also very sensitive to drought, so if you have had dry weather you will need to water your tree.
They are also susceptible to the Wooly Adelgid pest.
These links have more information.