Some of our little lime hydrangeas are looking a little dried out. Can we trim the dead branches? They were only planted last August. Tried giving them more water to no avail. They are in partial
Sun, mostly sun under black walnut tree. Others seem to be doing fine but a few don’t seem to be coming along as well. In Toronto
Sorry to hear that you are having problems with your Little Lime Hydrangeas Hydrangea paniculata. This is a compact version of the popular Limelight Hydrangea. You can expect this shrub to grow between 3 to 5 feet tall and the same in width. It does enjoy full to partial sun, but in full sun it will need to be well watered. Pruning of your Hydrangea should be done in early spring or early fall as this hydrangea blooms on new wood. Pruning your hydrangea will encourage new growth, help improve stem strength, and ensure heavy blooming. Prior to pruning away those dead stems, I would carefully check that they are actually dead. To do this start at the top and scratch the stem until you see evidence of green. If there is still green in the stem, then it is still alive. Wait until the fall to prune these back. You did mention that some of these shrubs are planted beneath a Black Walnut tree, this indeed may be what is ailing your hydrangeas. Black walnut trees exude a chemical called juglone that is toxic to many plants, and Hydrangeas are one of those plants that are susceptible to this effect. Below is a link to query on this subject that describes this and suggests ways to lessen the effect. I hope you will find this helpful. Best of luck with your Little Limes!