Hydrangeas, with their lush, rounded blooms resembling cheerful pom-poms, bring undeniable charm to any garden. Their flowers, ranging in vibrant shades from cornflower blue to soft purples and magentas, make these shrubs an eye-catching favorite. But unlike many other perennials that bloom in just one color, the same hydrangea shrub can actually change color from season to season—a little magic trick that taps into the secrets of soil acidity. By understanding and adjusting your garden’s soil, you can coax these floral wonders into a kaleidoscope of hues.
Let’s start with the fundamentals. There are about six types of hydrangeas that flourish in gardens across the United States. Among these, bigleaf hydrangeas (Hydrangea macrophylla) are the most sought-after, sporting either the classic pom-pom appearance or stylish clusters of blossoms. If you’re aiming to introduce color variety to your landscape, these are the hydrangeas to focus on. Smooth hydrangeas (Hydrangea arborescens), on the other hand, boast slender leaves and extended stems, while panicle hydrangeas (Hydrangea paniculata) take on a conical flower form. Typically, hydrangeas thrive in USDA Hardiness Zones 5 to 9, though different varieties may have slight variations in hardiness.
The ideal time to plant hydrangeas is during the fall or early spring when conditions allow their root systems to develop strongly before bearing the brunt of intense weather, such as scorching summer heat. According to Mallory Micetich, a home and garden expert with Angi, hydrangeas flourish beautifully in garden beds, large pots, or as part of
shrub borders.
Armed with these essentials, you’re ready to explore five expert tips to grow thriving hydrangeas and enjoy their color-changing magic in your garden. Here’s what to know.
Throw Hydrangeas Some Shade
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Hydrangeas can often thrive in shaded areas of yards where many other plants cannot survive, says Teri Valenzuela, natural science manager at Sunday Lawn Care. That means you can incorporate blooming hydrangeas in locations where you receive less sunlight, but want to add color, season-long blooms, and perennial growth to your garden.
That being said, most hydrangeas need roughly four to six hours of sunlight a day, or else they won’t get much flower growth. And while they can handle shade, you’ll want to avoid planting hydrangeas underneath a tree because their roots will have a hard time competing for water and nutrients.
Related StoryPlant in Well-Drained Soil
Whether they’re growing in a garden or a pot, hydrangeas don’t like to be in standing water, so make sure the soil is well-drained, says Bryan Clayton, CEO of GreenPal, a site that connects homeowners to lawn care services. You also want to give hydrangeas some space, planting them at least three feet apart from one another.
Water hydrangeas regularly, especially during dry spells, Clayton says.
“They need consistent moisture to thrive, but don’t overwater,” he advises. “If you notice the leaves yellowing that might mean you’re putting too much water on them.”
Related StoryChange Up Their Colors
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Hydrangeas are a fun flower (and a neat at-home science project) because you can make their blossoms change color by adjusting the soil’s pH level, Micetich says. Not all varieties will color-shift, so if this is something you want to try, look for bigleaf hydrangeas, with mophead and or lacecap heads. You’ll also have more control when it comes to adjusting the soil’s pH if you plant your hydrangeas in a pot or separate flower bed, she points out.
Start by testing your soil’s pH level with a $13 at-home kit. From there, you can make the soil more acidic or basic based on the color you want to end up with, Micetich says.
“In general, more acidic soil will turn them blue or bluish, while basic soil will turn them a more pink color,” she advises.
She provided this pH scale for hydrangea colors:
Bright blue: 4.5Muted blue: 5Violet blue: 5.5Purple/blue and pink: 6-6.5Pink: 7.0 or higher
To make your soil more acidic, Micetich recommends adding a soil acidifier, 25-5-30 fertilizer, coffee grounds, citrus peels or grass clippings to help lower the pH levels.
To create more basic soil, add 25-10-10 fertilizer, ground lime, or crushed eggshell to the soil.
Then, be patient. It usually takes your hydrangeas a few months to adjust to the soil, Micetich points out.
Related StoryCreate Bouquets
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Gift yourself or your neighbors some fresh-cut flowers every once in a while, Valenzuela says. Not only will they bring a little cheer to your space, but you’ll do the shrub good, too.
“Hydrangeas tend to bloom all growing season long, but can benefit from a well-timed trim,” she says. “While their blooms are beautiful on the plant as is, by pruning hydrangeas for cut flowers indoors, you can actually encourage more flowering outdoors.”
Related StoryAdd a Dash of (Epsom) Salt
We’ll leave you with a lesser-known tip: Ben Hilton, founder of The Yard and Garden, a site which offers gardening advice, suggests applying Epsom salt (i.e. magnesium sulfate) to the soil surrounding your hydrangeas. It can help improve their colors, promote more robust blooms, and reduce the risk of fungal infections.
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