June Hydrangea Help from Hydrangea Headquarters

When I met with customers last Friday, a number of them had questions about hydrangeas. Here were some of the concerns that came into Hyannis Country Garden on June 6th.

Q. My hydrangea flower buds and leaves are suddenly turning black!

A. I asked this customer if the plant had recently been fertilized or if another garden product was used around the plant. When a synthetic fertilizer is either applied to a dry plant or mixed too strongly, that can cause fertilizer burn which typically causes both flowers and leaf edges to turn black or dark brown. Similarly, weed killers and weed or crab-grass prevention products can also damage hydrangeas in this way. Sometimes such products have been applied to an adjacent lawn, and has either been tossed around the hydrangea by the spreader or washed onto the shrubs by a hard rain. The customer remembered that the plant in question was right next to a place where a weed killer had been used.

Q. My hydrangea flowers are opening but they aren’t very blue…

A. When this customer showed me a photo of their hydrangea, I could tell that all was as it should be. When bigleaf or mountain hydrangea flowers first start opening they are often pale, in shades of cream, pale pink or light blue. These plants don’t usually need more fertilizer or a more acidic soil…they just need time to develop. Most hydrangeas on Cape Cod become colorful at the end of June.

Q. Will the pink hydrangea that I see in your nursery turn blue when planted?

A. Since Cape Cod has naturally acidic soil, most Hydrangea macrophyllas and Hydrangea serratas will not stay pink when grown in our native ground. But their color is also genetically determined, as well as influenced by the pH of the soil. For example, in alkaline soil the variety called Summer Crush is a rich pink but in Cape soil it’s a rich purple, not blue. The Let’s Dance Can Do that is pink in our nursery right now will be lavender in acidic growing conditions. Note that if you buy a plant that’s pink it doesn’t change color quickly. It might take a year or more for a pink flower to change to blue or purple.

Also, we often stock some Hydrangea arborescens, the smooth hydrangeas, that have pink flowers. Invincibelle Spirit II is an example of a pink flowering arborescens. These will not change color no matter if they are growing in acidic or alkaline soil.

Q. I want to plant a hydrangea in my foundation bed that’s in part shade. Which plant will stay shorter?

A. Most of the plants in the Let’s Dance series stay under 4 feet tall. They are also plants that will flower on new stems if they go through an extremely cold winter or should they get pruned down to the ground.

Q. When I walked by a neighbor’s house, I saw a hydrangea with dark, almost purple leaves. Is this normal or was something wrong?

A. Some hydrangeas have been bred to have dark foliage. In the hydrangea section of our nursery right now we have a variety called Eclipse in stock. So chances are your neighbor has an Eclipse or another hydrangea that has dark leaves such as Pink Dynamo.

If you have questions about your hydrangeas, bring photos or samples into the store to speak with our staff members. We also have a number of events coming up where hydrangeas will be discussed, including the Flower Power Happy Hour on June 20th. Check the events page for details.