Hydrangea Colors Explained

Amber Randhawa Homeowner and Homebuyer Tips

With 75 distinct varieties that love the mild Georgia climate, hydrangeas are an easy and colorful additional to your outdoor scape. They’ve been a staple in Southern lawns for generations, with early cultivators soon noticing that their flowers seem to change colors on a whim.  Eighteenth century gardeners experimented by burying rusty nails near the plants, pouring tea in the soil, or even chanting spells around their hydrangeas. But as it turns out, hydrangeas’ color depends on the pH level of their soil. The more alkaline the soil, the pinker the flowers. This means you can change the color of hydrangeas yourself by altering the chemical balance.

Determining Your Soil’s pH Level

Collect a sample of your soil in a small cup, then pour simple white distilled vinegar over the dirt. If the solution fizzes, the pH level is high and your soil is alkaline. If it doesn’t fizz, then the soil is either neutral or acidic. You can also purchase a soil test kit or even have your soil tested professionally by your local county extension service, but we recommend the vinegar method, especially if you have small budding scientists around to help!

Give Your Yard the Blues

To make pink hydrangeas turn blue (or to keep your blue ones from turning pink), increase the acidity of your soil by adding any organic material. Coffee grounds, crushed egg shells and ground-up citrus peel are some of the easiest and more natural ways to do this. Work the mixture into the soil around the base of your hydrangea plant, and then water it. You’ll need to repeat the process periodically, so save your peels, shells and grounds in a little bowl on the counter top and whenever the bowl is full, take it outdoors to feed the hydrangeas. You can also add diluted aluminum sulfate to the soil, which can be found at home improvement and gardening stores, or can be ordered from Amazon.

Pretty in Pink

If you prefer a pinker flower, you can increase your soil’s alkalinity with garden lime, also available at home improvement and gardening stores and on Amazon. There are no composting alternatives that will do the job unfortunately. You’ll need to add additional lime regularly to keep your blooms pink, and some soil can be very stubborn due to the amount of aluminum it contains, making it naturally more acidic. Flowers that bloom from this stubborn soil may lighten only to purple, which can be a treat in and of itself!

What About White?

White hydrangeas are a separate species from their chameleon cousins. If you have white hydrangeas in your yard, they will remain white no matter what you add to the soil. Similarly, there’s nothing you can add to your soil that will turn a blue or pink hydrangea white. However, keep in mind that white varieties thrive in a less acidic environment, so plant them in a different area, away from the ones you want to turn to blue.

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