Big, beautiful hydrangea blooms are one of the best parts of summer. (Right up there with backyard barbecues, fun pool floats, and chilled rosé, IMHO!) And there are so many different kinds to admire, from whisper-pale pinks, lavenders, and sky blues to deep, vibrant fuchsias and intense, purpley blues. They're instant mood-lifters, whether part of the landscape or arranged in a vase inside.
If you're lucky enough to have these beauties growing in your yard, you know what I mean. But did you know that you can change the color of the blossoms to your liking, even on a pre-existing hydrangea bush that has been blooming pink or blue its whole life? Like a magic trick! But really, it's basic science: The color of a hydrangea blossom is determined by the pH level of the soil it's planted in. More acidic soil, which has a lower pH, yields blue flowers, and alkaline soil, which has a higher pH, yields pink flowers. Change the pH, change the color!
If your hydrangeas are pink (meaning your soil is alkaline) and you want them to turn blue, make the soil more acidic by adding aluminum sulfate or a soil-acidifying treatment, which can be purchased at any garden center. Adding pine needles, compost, and even coffee grounds to the soil can help, too. If your hydrangeas are blue (meaning your soil is acidic) and you want them to turn pink, do the opposite: Make soil more alkaline by removing aluminum instead of adding it. This can be done by applying garden lime, also available at any garden center.
If you're not sure what kind of soil you have, you can make an easy, homemade test using distilled water (which has a neutral pH), white vinegar (acidic), and baking soda (alkaline): Just follow Garden Therapy's simple instructions here. The color change won't happen overnight, but it will happen. So happy gardening—and happy summer!
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