14 Plants You Should Never Grow Next to Hydrangeas

A hydrangeas garden full of blue and violet blooms — Photo:
Masaaki Ohashi / Getty Images

Hydrangeas are some of the most beautiful flowering shrubs. Known for their spectacular blooms in a range of colors, they work great in a late summer or early fall garden. However, it turns out that some plants don’t play well with hydrangeas. These plants include other flowers, trees, vegetables, and herbs, many of which prefer other soil types or need different care. Some even emit chemicals that are harmful to hydrangeas and other flowers.

Ahead, we spoke to garden experts about which plants to keep away from your hydrangeas to ensure that these showy shrubs thrive.

Christine Schaub, host of the home and garden YouTube show Come on Over
Andrew Connolly, owner of Little Flower Cottage, a seller of flowers
Evan Torchio, expert arborist and founder of Tree Menders

01 of 14

Thyme

A woody herb, thyme prefers dry soil, the opposite of what hydrangeas like. "Thyme is often drought-tolerant and wilts in the kind of moisture hydrangeas crave," says Christine Schaub, host of the YouTube show Come on Over. As an herb, thyme also tends to thrive in the sunniest of sunny locations, something tender hydrangea leaves reject, she says.

02 of 14

Lamb’s Ear

Known for its pretty foliage, lamb’s ear is another dry-soil, drought-tolerant plant, and it cannot enjoy the same environment as hydrangeas. "Their silvery, fuzzy leaves don’t like to get wet, and when hit with the kind of humidity hydrangeas require, lamb’s ear’s leaves will yellow, and the plant crowns will rot," says Schaub.

03 of 14

Black Walnut

This tree produces juglone, a chemical harmful to many plants. "Specifically, juglone stunts the growth of hydrangeas by stopping water uptake," says Andrew Connolly, owner of Little Flower Cottage, a seller of flowers.

04 of 14

Eucalyptus

Eucalyptus trees don’t do well with hydrangeas. "Eucalyptus are heavy feeders and can deplete the soil of the most essential nutrients," says Connolly. Thus, the hydrangeas will become malnourished next to the eucalyptus and might not be able to flower.

05 of 14

Lavender

Never plant lavender next to hydrangeas. "Lavender is notoriously finicky about soil moisture, humidity, and sun," says Schaub. Since it hails from the Mediterranean, lavender prefers dry, rocky, sandy conditions, conditions a hydrangea plant can’t cope with. "And lavender will let you know it’s unhappy by turning yellow, then brown, and the hollow stem will snap right off," she says.

06 of 14

Daffodils

Daffodils can be toxic to other plants. "Their roots secret a substance that inhibits the growth of any neighboring plants," says Connolly.

07 of 14

Marigolds

While a great companion plant for many herbs and vegetables, marigolds do not get along with hydrangeas. "These orange-toned beauties want sun all day, every day. And they like their 'feet' in drier conditions," says Schaub. If placed in moist ground that hydrangeas like, your marigolds will droop, turn yellow, and eventually die.

08 of 14

Bamboo

Technically a species of grass, bamboo shouldn’t grow next to just any plant. "Bamboo can cast too much shade, depriving hydrangeas of the sunlight they need," says Evan Torchio, founder of Tree Menders. Plus, certain bamboo varieties are considered invasive, as they spread aggressively and therefore should be kept in a confined space like a concrete planter away from native plants.

09 of 14

Limelight Hydrangea

Surprisingly, not all hydrangea varieties get along. "Planting different hydrangea varieties too close together can lead to cross-pollination issues," says Connolly. And placing too many different hydrangeas on top of each other can impact the color and intensity of their flowers, especially in closely related hydrangea species.

10 of 14

Roses

Roses can compete with hydrangeas for nutrients and water. This is particularly true in small gardens. "Additionally, some rose varieties may prefer different soil conditions than hydrangeas," says Torchio.

11 of 14

Lilac

A flowering bush, lilac is an aggressive grower. "It can quickly outcompete other plants for resources," says Torchio. Plus, these flowers prefer well-drained soil, the opposite of what hydrangeas like.

12 of 14

Anemone

Anemone blooms in mid-to-late summer just like hydrangeas, but these flowers should never be planted together. Hydrangeas grow big, towering over this low-lying plant. "If the anemone base is too shaded, it will not bloom, and then you’ll miss the best part of this hardy plant," says Schaub.

13 of 14

Garlic

Garlic and hydrangeas don’t get along. "While not commonly planted in ornamental gardens, garlic can affect the growth of floral plants like hydrangeas," says Connolly. This is because garlic releases allelopathic chemicals that can harm flowers.

14 of 14

Sunflowers

Known for their height, sunflowers can shade out hydrangeas. "Also, some studies suggest that sunflowers may have allelopathic properties, releasing chemicals that can inhibit the growth of nearby plants," says Torchio.

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