My Endless Summer hydrangeas appear to have had their stems go dead. They are growing from the base of the plant. I live in Oshawa. The plant gets morning shade and afternoon sun. They were planted last year. I mounded mulch around them in the winter. What should I do to encourage growth and should I cut back the dead branches to the ground?
Hydrangea macrophilla “Endless summer” has become very popular with gardeners because of its ability to bloom on both old and new growth. Also it is supposed to have excellent winter survival capabilities – great for an Ontario climate. However, it is quite possible your hydrangea sustained some winter damage, especially as it is a young plant. This year we had a strange spring with pretty cold temperatures in March when it should have been warming up. You may well have some frost damage, which has left you with dead stems. Thankfully you had the foresight to mulch around the roots of your plant, which provided some protection. It would have been even better if you had surrounded your plant with a burlap screen, which could have helped save its branches from the elements. Remember to do this next winter.
The good news is that Hydrangea macrophilla is quite tough. Mind you if you cut it back too severely or to the ground it will not bloom this summer or possibly the next. However, it should survive and if you protect it next winter you should get blooms again.
First you need to determine if your plant’s stems are indeed completely dead. Scrape a fingernail or sharp knife into the bark of a stem you suspect as being dead. Start at the top. If you see some green then it means the branch is alive. Examine closely looking for any swelling buds which also indicate life. If you determine the whole stem is dead then cut it out completely. Dead stems will probably be brittle and dried out. If its only the top of a stem that is dead, remove the dead part by making a 45 degree angle cut about 1/4 inch above a bud. Only leave healthy wood and/or new growth from the base of the plant. These plants are not great feeders so there is no real need to fertilize. However, do make sure that the soil is kept moist during the growing season.
All being well your plant should grow back but most likely you will have to give up on blooms this year. For even more information on caring for hydrangea please check the following websites:
www.endlesssummerblooms.com/design-and-grow/planting-and-care
www.rhs.org.uk/advice/profile?pid=516