How To Grow And Care For French Hydrangeas

We can't get enough of these seductive blooms. Here's how to choose, plant, and care for French hydrangeas.

French Hydrangeas
In this Macon, Georgia garden, bluehydrangea macrophylla set a stunning path to a table simply set with fresh cut blooms. Photo: Ralph Lee Anderson

Picking out French hydrangea, hydrangea macrophylla , is like ordering iced tea. You're going to have to make a decision: Sweet or unsweet? Mophead or lacecap? There's no right or wrong answer—it's about personal taste. Hydrangea macrophylla, also called bigleaf hydrangeas, have blooms categorized as mopheads or lacecaps. And like iced tea—sweet or unsweet—both are Southern staples.

Mopheads are the most popular. Coveted for their voluptuous blooms, ranging in size from as small as a baseball to bigger than a cantaloupe, they fill the summer border with heavenly shades of blue, pink, and white the way no other flowering shrub can. Because they lose their leaves in winter, it's a good idea to sandwich them between evergreens, such as camellias, and low-growing azaleas or mondo grass. Be mindful of where to plant French hydrangeas, as consumption is toxic to pets and humans.

Plant Attributes

Plant Attributes
Common Name: bigleaf hydrangea, French hydrangea, lacecap hydrangea
Botanical Name: Hydrangea macrophylla
Family: Hydrangeaceae
Plant Type: Perennial, Shrub
Mature Size: 3-7 ft. tall, 3-5 ft. wide
Sun Exposure: Partial
Soil Type: Well-drained
Soil pH: Acidic (5.0 to 5.5)
Bloom Time: Summer, Fall
Flower Color: Pink, Blue, White
Hardiness Zones: Zones 3-9 (USDA)
Native Area: Asia
Toxicity: toxic to dogs, toxic to cats, toxic to pets , toxic to people

French Hydrangea Care

French hydrangeas, or bigleaf hydrangeas, are categorized as mophead or lacecap. Mophead hydrangeas have big, puffy balls, while lacecaps are similar, with smaller buds in the center. Lacecaps may be more subtle but are equally stunning when in bloom. Their flower heads are slightly domed and ringed with delicate fertile florets, and they beckon bees and butterflies to the garden. Like mopheads, their flowers float atop broad, bright green, deciduous leaves. While mopheads may be showier, lacecaps are sublimely elegant. Showcase drifts of these ethereal blooms in woodland settings with high shade and combine with sweeps of ferns and hostas. Hydrangeas can become invasive in some environments but are generally not considered invasive.

Light

Bigleaf hydrangeas thrive in the morning sun and light afternoon shade. If hydrangeas receive too much direct sunlight, these plants will scorch, and the leaves with droopy or turn yellow from overexposure.

Soil

French hydrangeas love moist, well-drained soil. These plants thrive when organic matter, such as manure or compost, is amended to the soil to help it retain moisture. Layering organic materials near the base of the shrubs can help protect the plant's growth.

Water

French hydrangeas need a balanced watering schedule, so it is not overwatered or scorched when too dry. The best way to test if your plant needs more water is to ensure the top few inches of soil remain moist. Make sure when watering that it reaches the roots, so if you are experiencing drought conditions, then provide hydrangeas with a deep watering without saturating the soil.

Temperature and Humidity

Moderate temperatures are best for French hydrangeas. This plant will need more water in areas that experience hot, humid summer conditions. These plants are typically hardy, but it depends on the variety.

Fertilizer

Organic compost or balanced fertilizers will help hydrangeas grow. Add the fertilizer to French hydrangeas during the spring for best results, as adding organic material in late summer will leave the plant susceptible to winter frost during dormancy.

Types of French Hydrangeas

  • 'Abracadabra Star': Pink summertime blooms with black stems and shallow roots.
  • 'Cityline Paris': Pink-red flowers that are mildew resistant. These plants mature to a green color.
  • 'Cityline Vienna': Flowers bloom in blue or pink varieties depending on the acidity in the soil.

Pruning

French hydrangeas that flower once, such as 'Nikko Blue,' bloomed on last year's growth. Prune just after flowering in summer. Repeat-blooming French hydrangeas, such as 'Blushing Bride' and 'Dooley,' flower on both old and new growth—prune these at almost anytime. Remove older or dead branches back to the group using loppers to keep your hydrangea healthy. Removing old canes and dead blossoms can help promote new growth. You can tell if a branch is finished by using a blade to scratch the top layer of the stem and examine it for signs of green growth, meaning it is still healthy.

Propagating French Hydrangeas

One way to propagate French hydrangeas is through cuttings. Take cuttings in the spring or winter, depending on your preferences.

  1. Look for branches off the main stem with a few leaf nodes, and use sharp pruners or a knife to cut off a strong, healthy stem tip.
  2. Remove most of the leaves on the branches so that the cutting can focus its energy on new growth instead of retaining old growth.
  3. Place cutting in a root hormone solution.
  4. Plant cutting in moist, well-drained soil and secure it in an area with partial sunlight. Most varieties are planted in late spring or early summer.
  5. Remember to water cuttings thoroughly, but don't oversaturate the ground.

How to Grow French Hydrangeas From Seed

  1. Hydrangeas can start from seeds from a garden center or collect hydrangea seeds from spent blooms and allow them to dry in a brown paper bag.
  2. Start seeds in potting soil by sowing them directly on top of the ground.
  3. Keep the soil well-drained but moist, and choose a sunny location.
  4. After about 14 days, the seeds should show some signs of growth and can be treated similarly to cuttings.

Potting and Repotting French Hydrangeas

When buying French hydrangeas, look for more than just pretty flowers. Choose a full plant with equal branching on all sides. Fat buds or flower heads should cover the stems that are ready to open—or opening in late spring and early summer. Leaves should be bright green and not drooping (an indicator of infrequent watering).

French hydrangeas love moist, well-drained soil, morning sun, and light afternoon shade. Water as soon as you get them home, saturating the ground in the pot. Before planting, play with the placement. Space most French hydrangeas three to four feet apart, but check the tag to see how wide your selection will grow. Dig a hole two to three times as wide as the pot but at the same depth. Remove the plant from its container, and set it in the center of the hole. Gently loosen the sides of the root ball with your fingers. Fill the hole with a mixture of half the original soil and half compost. Mulch and water regularly to help establish your plant. If you buy a repeat bloomer, it's essential to water, feed, and remove spent blossoms regularly to encourage new flowers.

Overwintering

French hydrangeas only require a little winter maintenance. After blooming ends, protect the shrub by deadheading the flowers. Use mulch to protect the plant's roots during the colder months.

Common Pests & Plant Diseases

French hydrangeas are susceptible to fungal, bacterial, and viral diseases. Some fungal diseases include leaf spots, powdery mildew, and Botrytis blight. Bacterial wilt can occur when hydrangeas grow in areas with hot, humid temperatures and heavy rain, which can also cause root rot. Some pests include aphids, which insecticidal soap can help treat.

Common Problems With French Hydrangeas

French hydrangeas can fail to bloom because of an imbalance of light, water, or fertilizer. When hydrangea care is mismanaged, these plants are susceptible to various issues.

Leaves Turning Brown

Hydrangea leaves and blooms might turn brown during drought or extreme heat periods. Lack of water, or dry soil conditions, will impact the plant's growth, meaning more frequent watering is needed.

Curling Leaves

Curling leaves indicate over- or under-watering, dry soil conditions, or nutrient deficiency. Other reasons for curling leaves include fungal and insect infections. When disrupted by these conditions, hydrangeas have weakened plant tissues, which causes curling to occur.

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