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Answers to the three most-asked questions about hydrangeas

In Western Washington’s naturally acid soil, hydrangeas planted in the ground stay blue but in potting soil they lean toward pink.
In Western Washington’s naturally acid soil, hydrangeas planted in the ground stay blue but in potting soil they lean toward pink. The News Tribune

As the end of July nears, you can continue to harvest fruits and vegetables, deadhead faded blooms from perennials and annuals and pay close attention to the watering needs of containers and hanging baskets.

More importantly, this column is Part 2 of how to enjoy hydrangeas, so be happy that this handsome shrub loves to grow in Western Washington.

Here are the most asked questions about hydrangeas over the years:

Question. How does one change the color of hydrangeas? Pink is my favorite color. I have a white hydrangea and for two years I have added lime around the base of the plant but nothing happened.

Answer. Not all hydrangea varieties will change color. White hydrangeas stay white no matter what you add to the soil.

The common mophead or hydrangea macrophylla will turn pink if the soil pH is above 6.5 and turn blue below 5.5. Anything in the middle becomes purple or lavender. In our naturally acid soil, hydrangeas planted in the ground stay blue but in potting soil they lean toward pink.

Adding sulfur (most often sold as aluminum sulphate) will make the soil acid and the flowers baby boy blue. A few cups of lime around the base of your hydrangea shrubs will slowly turn the soil less acid and more feminine pink. Apply either product in the fall or early spring and by summer your blooms will transgender — unless they are white or cream and stick with being gender neutral. .

Q. How big will hydrangeas become? I want to try growing one in a container.

A. New, compact hydrangea varieties are best in a container as they can be pruned to stay under 4 feet tall and still produce flowers.

Most hydrangeas, especially the common big leaf mophead varieties and the Pee Gee varieties, grow into giant shrubs up to 6 feet tall and 6 feet wide.

Read plant labels at the nursery to discover the new dwarfs.

Strawberry Sundae is a creamy-white-turning-pink plant with pointed blooms. Edgy Hearts is a mophead that stays under 3 feet, and is perfect for pots. The Cityline series (Venice, Paris and other city names) will bloom on new and old wood, so pruning them down one third each spring will not prevent these hydrangeas from flowering each summer.

Q. What are the hydrangeas that take full sun? I have the blue variety but it wilts every afternoon when we have sunny weather.

A. Most of the paniculata or Pee Gee hydrangeas do best in full sun and can take the afternoon heat. The climbing hydrangeas and the oak leaf hydrangeas also stand up to summer heat.

Perhaps the most impressive of all hydrangeas are the huge blooms of the Incrediball hydrangeas. These come in pink and white and are from a family called Smooth Hydrangeas or Hydrangea arborescens. These hydrangeas are not only sun-loving but also great at tolerating super cold winter weather.

Look for the Invincibelle series (Wee White, Mini Mauvette) and the much larger Incrediball series with flowers the size of basket balls.

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