How to Create the Perfect Soil for Hydrangeas for Healthier, More Vibrant Blooms

Hydrangeas are one of the most popular garden flowers. This perennial plant adds charm to front yards, backyard garden beds, container gardens, and more with its beautiful, oversized blooms. One way to ensure these plants keep performing is to maintain their soil quality. Hydrangeas need a perfect balance of moisture, organic matter, and adequate drainage to thrive. To help you produce healthy, vibrant blooms, we spoke to gardening experts who shared their tips for creating the best soil for hydrangeas.

Best Soil for In-Ground Hydrangeas

Hydrangeas planted in the garden perform best in well-draining, moist, organic-rich soil. The ideal pH depends on the type of hydrangeas you are growing. Typically, the pH should be between 6 and 7 as hydrangeas prefer slightly acidic conditions. However, Linda Langelo, a horticulturist specialist at Colorado State University Extension, says a more acidic pH of 5.5 to 6.5 can help promote blue flowering in certain hydrangea types, such as Hydrangea macrophylla varieties.

Best Soil for Potted Hydrangeas

Growing hydrangeas in containers is an easy way to add beauty to a patio, balcony, or container garden. Container-grown hydrangeas have similar soil requirements to in-ground blooms, needing well-draining and nutrient-rich soil to thrive. "Equal parts of sand, silt, and clay will do the trick," says Mary Woolman, woody ornamental and edible product manager for Star Roses and Plants. Make sure the bottom of the container or pot has a drainage hole so excess water doesn't get trapped inside.

How to Create the Best Soil for Hydrangeas

If your soil isn't ideal for growing healthy hydrangeas, there are some steps you can take to boost its organic matter content and improve drainage to make it more hospitable for these perennials.

Test Your Soil

Testing your soil before adding any amendments is essential. According to Langelo, a soil test provides data on pH, soil structure, nutrients, and salinity. "The laboratory test can give you solutions to amend the soil to keep your hydrangeas healthy," she says. "There are soil tests you can purchase, but the most reliable is letting a lab do a test. Most labs require a cup of dry soil in a breathable bag." Once you know the composition of your soil, Woolman says you can add more of what it’s lacking.

Improve Drainage

Whether you're growing hydrangeas in the ground or in containers, well-draining soil is essential. While these blooms like moist soil, root rot and other fungal diseases can develop if their feet get too wet. To test soil drainage, dig a hole in the ground and fill it with water. If it drains in 24 hours, your soil is well-draining. If it takes longer, Woolman recommends adding sand or very fine rocks to improve drainage.

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Add Coconut Coir

Work coconut coir into your garden or potting soil to improve its structure, aid with aeration, and help your plants with nutrient absorption. Langelo says you can do a 1:1 ratio of soil to coconut coir, which can be found online or at local plant nurseries.

Use Sphagnum Moss

Another great soil amendment, sphagnum moss helps with water retention and improves aeration in the soil. Langelo says to amend your soil with no more than 30 percent sphagnum moss. "Overdoing sphagnum moss without regularly watering the hydrangea can turn the moss into a hardened state, like cement," she says. "In periods of extended drought, supplemental watering for hydrangeas is necessary and keeps the sphagnum moss from hardening."

Top With Mulch

Hydrangeas prefer consistently moist soil. Mulch prevents the soil from drying out quickly and also suppresses weeds. "The best mulch for hydrangeas is either pine bark or pine needles, as they break down slowly, and naturally add acidity to the soil," says Langelo. "Pine needles and bark help suppress weeds and retain moisture." Fall leaves can also act as mulch, adding nutrients and improving moisture retention in the soil as they slowly break down.