Everything You Need to Know About the Best Soil for Hydrangeas
Hydrangeas are easily one of our favorite flowers to see in a summer garden. From their near-constant bloom power to the oversize showy florets that attract pollinators and even their shade-loving nature (which works wonders to brighten up borders and corners)—there are a million reasons these perennials make our list of favorites.
But like many garden shrubs, hydrangeas have special requirements when it comes to the kind of soil they need to thrive. Whether you’re troubleshooting an unhappy hydrangea or looking to prep a spot for your latest planting—keep reading. We’ve got the rundown of everything you need to know about hydrangeas and their soil requirements right here. Ready to get your hands dirty? Let’s dive in.
When to Plant Hydrangeas
Before we get into too much detail on the soil requirements, it helps to know a little bit about when to plant hydrangeas—since this, just as much as soil content, will help set your plant up for garden success.
Since hydrangeas typically start blooming in late spring, the best time of year to plant them is in fall or early spring. Although they can technically be planted any time of year (as long as the ground isn’t frozen), doing so during these times will optimize your bloom season and will also help avoid any unnecessary stress on your plant due to hot summer temperatures.
How to Plant Hydrangeas
Another thing to note about planting hydrangeas is that it’s best done in stages. You’ll want to start by choosing a location for your hydrangea, amending the soil, and then digging the hole—all before removing your plant from its pot.
Because hydrangeas have a somewhat sensitive root system, it’s best to prepare a hole before removing the plant from its pot, especially if you’re planting in the summertime when roots will dry out more quickly.
Soil pH for Hydrangeas
Now that we’ve gotten some hydrangea basics out of the way let’s dive into the nitty-gritty (pun intended) of their soil requirements. When we talk about soil pH, we’re referring to how acidic or alkaline it is.
While hydrangeas can grow in both acidic and alkaline soils, they can change their color drastically, mainly if you’re growing Bigleaf hydrangeas. When soil pH is 6.5 or lower (acidic soil), your Bigleaf hydrangeas will be blue. This is commonly seen in eastern coastal climes around Cape Cod or Martha’s Vineyard.
When the soil has a pH higher than 6.5 (alkaline), the flowers will be pink. This is more common in western climates, like in the mountains west of the United States. Not all hydrangea species will undergo such a drastic transformation based on soil pH. When growing white and green budding varieties, for example, they rarely change color due to the chemistry of your soil.
You can also play with changing the pH of your soil for different colored blooms. While this takes several months to achieve, you can amend your soil with acidic or alkaline fertilizers to change its chemistry and the colors of your blooms. The best way to do this is first to research your soil, then visit a nursery to see which products they have available to amend your soil to the desired pH.
Ideal Soil Structure for Hydrangeas
Besides soil chemistry, there’s also something called soil structure to consider when planting hydrangeas. Soil structure refers to the particle size of your soil—whether it’s clay, loam, or sand. Soil structure determines how well your soil drains and also how well it retains moisture between waterings.
This is important as it will help you determine how frequently to water your hydrangeas. But beyond that, you’ll also want to make sure to amend your soil so that it’s draining properly. Hydrangeas don’t like wet feet. In other words: You want a soil that’s draining really well. You’ll also want a soil that’s nutrient dense. The ideal soil type for hydrangeas is rich, moist, well-draining soil.
How to Amend Your Soil For Hydrangeas
How you’ll achieve that will largely depend on where you live and how much you’ve already amended the spot where you’ll be planting your hydrangea. If you have a corner of your garden where you’ve spent ample time working the soil— chances are you have a lot less work to do than if you’re planting a hydrangea into unamended thick clay (or loose sand) soil at the edge of your yard.
When it comes to amending clay soils, the trick is to add lots of lightweight organic material. Compost mixes work well for this. This helps add nutrients back into the soil and also break up the clay—which is an important step to support new root growth and proper water drainage.
To amend a sandy soil, consider adding in heavier organic material (like aged manure). You can also add in compost mixes, but you may need more of them. Another important step when planting hydrangeas in sandy soil is to mulch around the base of your plant. Since water often evaporates faster in sandy soils (the opposite of water-laden clay soils), it’s vital to cover them up to help with moisture retention between waterings.
While you’re almost always guaranteed to get better results from your plants if you take the time to understand your specific soil needs, you may not have the time to take a deep dive into soil science. If that’s the case, focus on amending your soil with nutrient-dense, well-draining soil. In a pinch, you can use something like Miracle Gro Moisture Control Potting Mix.
Another thing to keep in mind? Amending your soil isn’t a one-time fix and forget-it solution. The best gardens and happiest plants (hydrangeas included) are fertilized annually.
Hydrangea Soil FAQs:
How do you make good soil for hydrangeas?
Hydrangeas do best in nutrient-dense, well-draining soil. How you amend it to achieve this will be slightly different depending on what kind of soil you’re starting with. A good rule of thumb is to focus on adding in organic material since this provides plenty of nutrients but can also break up thick clay soils (for better drainage) or add more moisture-retaining properties to sandy soil.
Where do hydrangeas thrive best?
Hydrangeas can thrive in a myriad of gardens but will do best in part-shade gardens (ideally morning sun and afternoon shade) in zones 3-7. When it comes to soil requirements (be it for new plants or transplanting), hydrangeas prefer rich, well-draining soils that can retain some moisture between waterings.
What type of soil is best for hydrangeas?
Loam soil is best. Loam indicates nutrient-rich soil, well-draining, and good at retaining moisture between waterings. This is the ideal soil structure for hydrangeas.
How do you prepare soil for hydrangeas?
To prepare your soil for hydrangeas, add in plenty of high-quality organic material, like a locally-sourced compost mix. You want to ensure your soil is nutrient-rich, well-draining, and yet still able to retain some moisture between waterings. If your soil tends on the sandy side (where water evaporates quickly), consider mulching around the base of your plant to lock in more moisture. Remember, hydrangeas are considered somewhat toxic, so it’s best to wear gloves when handling these plants for extended periods of time.
Soil for Hydrangeas: The Final Word
Feeling unsure about what kind of soil you have? The easiest way to tell is to start digging. Dig up a little soil near where you plan to plant your hydrangea. Extreme cases of clay and sand are pretty easily distinguishable since they look just like what you’d imagine.
For more nuanced cases, ask around. Gardening neighbors and local nurseries are excellent resources for understanding your soil composition. Chances are if you’re struggling to amend your soil (for planting hydrangeas or anything else), so are other gardeners!
For more, see our ultimate guide to growing hydrangeas in your garden and how to cut hydrangeas for a vase or bouquet arrangement.
Larissa is a writer, gardener, and herbalist living in the San Juan mountains of Colorado. Her writing has been widely published in lifestyle and personal finance publications all over the country, and she's also the creator of the weekly newsletter @rootedintribe.