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Hydrangeas — What makes these colorful flowers so popular?

Analysis by Dr. Joseph Mercola Fact Checked

hydrangea plant

Story at-a-glance -

  • Hydrangea is an easy-to-grow ornamental because several varieties can thrive in different climates and conditions
  • Research shows that hydrangea may benefit your health by managing inflammation and protecting your liver
  • Hydrangea can also beautify your garden

The hydrangea belongs to the Saxifragaceae family, with four species native to the United States encompassing diverse locations such as New York, Georgia, Oklahoma, Missouri and Tennessee.1 Beginner gardeners can gain plenty of experience cultivating this plant, because some varieties are easy to grow.2

Different hydrangea varieties you should be aware of

According to FTD by Design, there are numerous varieties of hydrangea, producing flowers of different sizes and colors:3

Bigleaf hydrangea (Hydrangea macrophylla) — Also called florist's hydrangea, garden hydrangea or French hydrangea, it's the most common hydrangea variety. It is known for its thick, shiny, heart-shaped and short-stemmed leaves, which can grow 4 to 6 inches long and 3 to 5 inches wide. There are three known types of bigleaf hydrangea:

Mophead hydrangeas — Flowers can be purple, blue or pink. It's the most recognized and popular hydrangea because of the large, puffy flower heads.

Lacecap hydrangeas — These are almost identical to mophead hydrangeas, although they have smaller fertile flower buds in the center and showy flowers around the flower head's edge.

Mountain hydrangeas — They slightly resemble lacecap hydrangeas, but tend to have smaller flowers and leaves.

A unique type of bigleaf hydrangea you should be aware of is the Endless Summer developed by Bailey Nurseries. It was made with the goal of blooming throughout the entire summer, even with old growth.4

Smooth hydrangea (Hydrangea arborescens) — This one is native to the U.S., and also known as wild hydrangea. It's usually grown as a hedge plant, although it can become a large shrub, sometimes reaching up to 6 feet tall. Smooth hydrangea flowers appear green upon the first opening, but whiten as the plant matures. Two popular smooth hydrangea cultivars include:

Annabelle — This is typically used to refer to all smooth hydrangeas, and was inspired by the town of Anna, Illinois, where it's said the first smooth hydrangea was discovered. This cultivar produces white and round flower heads resembling large snowballs, growing up to 12 inches in diameter.

Incrediball hydrangeas5 The shrub is classified as Hydrangea arborescens "Abetwo" Incrediball. "Abetwo" is actually the cultivar name, while "Incrediball" is the trademark name. This cultivar is called "Incrediball" because of the impressive size of the plant's rounded flower heads, which can resemble balls.

Panicle hydrangea (Hydrangea paniculata) — Native to Japan and China, it's also called limelight hydrangea.6 This plant produces white flowers at first, but as it matures, the flowers turn pink. A popular cultivar of panicle hydrangea is the grandiflora hydrangea, which can grow exceptionally large, reaching up to 25 feet tall and bloom pure white flowers.7

Oakleaf hydrangea (Hydrangea quercifolia) — These are known for their leaves, which resemble those from oak trees. During fall, the leaves tend to change color and are the only known type of hydrangea to do this. In addition, the leaves are either bright red, golden orange or deep mahogany.

As for their flowers, oakleaf hydrangeas develop white cone-shaped flower heads (which can be single blossom or double-blossom) that gradually turn pink as the plant matures.

Climbing hydrangea (Hydrangea animola ssp. Petiolaris) — Native to Asia, where it's called the "Japanese hydrangea vine," this hydrangea is gaining popularity because of its ability to climb walls and other structures, in some instances reaching 80 feet.

Climbing hydrangeas can also be planted as shrubs when there are no supporting structures present, reaching 3 to 4 feet in height. Once the plants mature, pleasantly fragrant white hydrangeas with lacecap-like flowers will bloom.

Take note that these are just some of the most basic types of hydrangeas. There are other unique hydrangea cultivars you can consider planting:8

  • Nikko Blue
  • Zinfin Doll
  • BloomStruck
  • El Dorado
  • Madame Emile Mouillere
  • Unique
  • Cityline Mars
  • Gatsby Pink
  • Blue Deckle
  • You and Me Together
  • Miss Saori

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Health benefits of hydrangeas

Historically, hydrangea has been used in various ways. Published research shows that this plant's potential health benefits include helping:

  • Promote kidney health — A study published in Evidence-Based Complementary and Alternative Medicine notes that coumarins found in hydrangea paniculata helped improve renal function and reduce renal oxidative stress in mice.9
  • Protect the liver — Results from a 2017 study indicate that compounds found in hydrangea macrophylla have hepatoprotective properties.10
  • Manage inflammation — Research published in Frontiers in Pharmacology note that hydrangea paniculata contains anti-inflammatory and antioxidant properties, which may benefit people who are affected with septic acute kidney injury.11

What can hydrangeas be used for?

Hydrangeas are renowned for being ornamental plants thanks to their attractive flowers.12 In addition to being nice to look at, hydrangeas can serve other roles in your garden. The Missouri Botanical Garden considers hydrangeas as one of the best plants to use as shrubs.13

Some hydrangea varieties are valued for their healing abilities. An article from the Journal of the American Herbalists Guild states that root bark from hydrangea arborescens is an effective analgesic for people experiencing pain in the urinary tract. The article also provides instructions on how to make tea easily from this plant:14

  1. Combine one-half to 1 teaspoon of dried bark with filtered water.
  2. Steep for 1 hour. Take 4 ounces only.

How to grow hydrangeas

According to The Old Farmer's Almanac, hydrangeas are best planted during spring or fall.15 If you're set on planting hydrangeas, take note of these tips for elegant and eye-catching flowers. Planting can be done via root cuttings:16,17

1. Select a hydrangea stem at least 6 inches long — a good time is between April and August — that has no flowers and is newly grown. New-growth stems have a lighter green color. If you live in an area with a colder climate where hydrangea tends to die, the hydrangea bush or shrub may consist of new growth.

2. Cut the stem just below a leaf node, or where a set of leaves will be growing. The cutting must be at least 4 inches long and have at least one additional set of leaves above the leaf node. Snip the cutting from the stem.

3. Remove the lowest pair of leaves from the cutting and trim flush to the stem. Remove the topmost set of leaves, leaving the two leaves nearest the base of the stem. Take these leaves and cut them in half, crosswise. If you have rooting hormone, dip the end of the hydrangea cutting in it. Although the rooting hormone can help increase the possibility of successfully propagating a hydrangea plant, you can still propagate hydrangeas without it.

Afterward, stick the cutting into well-drained damp potting soil containing plenty of organic matter or humus.

4. Cover the pot or container with a plastic bag, making sure that it doesn't touch the leaves of the cutting. Place the pot or container away from direct sunlight. Check the cutting every few days to make sure the soil is still damp. In two to four weeks, the cutting will be rooted and the propagation will be complete.

If you have enough space at home (whether a garden or a backyard), why not plant hydrangeas there? Here's how to plant hydrangeas outside:18,19

1. Dig a hole approximately 2 feet across and 1 foot deep. It should be as deep as the root ball. While hydrangeas can grow without difficulty in various soils, fairly rich, porous and moist soil is highly ideal. If you think the soil is poor quality, try adding more compost.

2. Set the plant in the hole and fill it half-full with soil. Water the plant first, and after the water is drained, fill the rest of the hole with soil and water thoroughly again. If you're planting multiple hydrangeas, space them 3 to 10 feet apart.

3. Fertilize the plant using a general-purpose fertilizer, such as 10-10-10 applied at a rate of 2 cups per 100 square feet in March, May and July. Water the plant soon after to help dissolve the fertilizer into the soil. It's not necessary to remove mulch when fertilizing. Ideally, water the hydrangeas thoroughly once a week or more frequently.

Rich soils don't need a lot of fertilizing. However, if the soil is light or sandy, feed the plants annually during late winter or spring. Excessive fertilizer will cause the plant to produce more leaves and fewer flowers.

4. For the first year or two after planting, and if there is any drought, make sure hydrangeas get plenty of water. If the soil is too dry, the leaves will wilt. During fall, cover the plants with bark mulch, leaves, pine needles or straw, to a depth of at least 18 inches. If possible, cover the entire plant (tip included) with cages made of snow fencing or chicken wire loosely filled with leaves. Avoid using maple leaves because of their tendency to break down quickly.

If you wish to grow a specific color of hydrangeas, determine the soil's acidity — it's a major factor. White blooms will always be white, while hydrangeas with naturally pink flowers tend to produce blue blooms. The closer the soil is to a balanced pH level of 6.5, the lighter the color of the hydrangeas.

Growing different types of hydrangeas

If you're looking to plant a specific type of hydrangea, you have to take note of certain characteristics, such as the soil and weather conditions the plant can thrive in. These factors play a role in when and how long it will take for these hydrangeas to bloom:20

Bigleaf hydrangeas — They grow well in moist and well-drained soil. A little shade is preferred because too much can lead to reduced flowering. Bigleaf hydrangeas bloom in June and July. If you want to plant any of the three types of bigleaf hydrangeas, take note of these requirements:

Mophead hydrangeas — This type tends to thrive well in areas in the U.S. with a level 6 hardiness zone. Mophead hydrangea flower buds can be sensitive to cold temperatures and may not survive winter months.

Lacecap hydrangeas — Just like mophead hydrangeas, lacecap hydrangeas can thrive in hardiness zone 6.

Mountain hydrangeas — They can thrive in hardiness zone 5, and can be a great choice in areas with late winter cold snaps because they have hardier flower buds.

Smooth hydrangeas — This type of hydrangea can tolerate warmer climates. Smooth hydrangeas can thrive in hardiness zones 4 to 9, with blooming time occurring between June and September.

Panicle hydrangeas — This hydrangea is said to be one of the few types of hydrangeas that require several hours of sun, and can even tolerate full sun exposure. Panicle hydrangeas are the most cold-hardy out of the hydrangea plants, thriving in hardiness zones 4 to 7 and flowering from mid- to late summer.

Oakleaf hydrangeas — These hydrangeas may survive drier temperatures and can be more winter hardy. However, oakleaf hydrangeas should be planted in well-drained soil, because they are highly sensitive to water log. Furthermore, avoid planting oakleaf hydrangeas in areas with deep shade, as this can cause the plant's fall foliage colors to fade.

Oakleaf hydrangeas can survive in hardiness zones 5 to 9, with flowers blooming in early summer and lasting until late summer.

Climbing hydrangea — Growing climbing hydrangeas isn't for the impatient, as it typically takes three to four years to show signs of growth. This slow-growing plant can be planted in hardiness zones 4 to 8, with blooming time occurring during early to mid-summer.

How to care for your hydrangeas and keep them alive

After you're finished planting, the main question becomes: "How do I keep my hydrangeas alive?" Here are some tips on caring for hydrangeas:21,22,23

  • Avoid planting hydrangeas in hot, dry and exposed locations. Lean on the safer side and grow hydrangeas in partial shade, as excessive shade can reduce flowering. Take note that most hydrangea varieties are susceptible to weather changes, which can lead to reduced blooms.
  • Water your hydrangeas properly. These plants enjoy deep watering at least once a week, especially during dry weather.
  • Mulch the plant to maintain cool and moist conditions for the roots.

Prune hydrangeas during the summer once flowering season finishes to ensure they grow well. Avoid pruning in the late fall, winter or spring if you want flowers. Pruning panicle and smooth hydrangeas in early summer can remove prospective flower buds. On the other hand, bigleaf and oakleaf hydrangeas flowers bloom on the previous year's growth. Pruning these hydrangeas during the fall, winter or spring may remove impending flower buds.24,25

All old flowering shoots must be removed down to where strong growth is seen appearing. Only prune stems that produced this year's flowers; otherwise blooms will not appear on the plants next year.26

Once your hydrangeas are in full bloom and you wish to make beautiful hydrangea arrangements, take note of these instructions from SF Gate on how to properly cut hydrangea flowers:27

1. Cut flowers that are fully mature — Petals must be fully open in the center of the bloom and color should be evenly developed across the flower head. Only cut hydrangeas in the morning the day after watering. Have a bucket of water on hand and place cut hydrangea stems in it. It's essential for the hydrangeas to stay hydrated until they are fixed in the arrangement.

2. Use clean, standard pruning tools like bypass runners when cutting hydrangeas — Cleaning the pruning tool is important to avoid crushing the stem and to help prevent bacterial contamination. Both these factors can shorten the life of a hydrangea arrangement.

3. Hold the pruning tool in your dominant hand so the blade is against the back of stem and tilted toward it at a 45-degree angle — Place your thumb in front of the stem, directly over the knife or pruning tool. Using your other hand, pull on the stem above the knife, slightly up and away from the blade.

Maintain pressure on the stem with your dominant thumb. The knife should end against your thumb, but should not have force behind it that'll cut your skin. Cut hydrangea stems that are slightly longer than your preferred length, and cut down to a leaf node or a lateral stem to maintain the form and health of the plant.

4. Cut hydrangeas have a vase life of six to 10 days — However, mature blossoms may wilt prematurely if air enters the stem and blocks the flow of water to the flower.

To reduce air bubbles that can reduce their life span, try recutting stems at a 45-degree angle with the ends under water, plunging the cut ends of the stems in boiling water for 30 seconds or smashing the ends of the stems with a hammer (although some sources highlight that this tip can cause problems with water uptake).

Removing foliage from hydrangea stems can be beneficial to direct more water to the flowers. It also pays to consider the size of the arrangement and the container you'll be using — shorter containers and arrangements can make it easier for water to travel up the stem and reach the flower.

How to dry and preserve hydrangeas

Once blooming season ends, hydrangeas turn either burgundy, brown, bronze or muted shades of cream and pale green. If you find it disheartening to see hydrangeas at this stage, don't worry. You can preserve these beautiful flowers by drying them. Lynn Couiter of HGTV shares these steps for drying hydrangeas:28

  • Allow flowers to dry naturally on the plants — This period runs from August to October. Hydrangeas are ready for drying when petals develop a "vintage" look or mature to the extent that the flowers look like parchment paper with pink or green hues. The flowers can also have a papery texture.
  • Avoid snipping hydrangeas during peak blooms or a rainy spell — There's a tendency that stems and leaves will hold too much water, and the flowers will not be able to dry fast enough. Timing is key, as you shouldn't wait too long or the flowers will turn brown.
  • Snip the flowers on a cool morning — Cut hydrangea stems at an angle with lengths measuring 12 to 18 inches. Remove leaves and place the stems in a jar, covering them with water about halfway. Place the jar in a cool spot out of direct light and check periodically.

Avoid crowding hydrangea stems in the container. The different lengths of stems will enable good air circulation. Hydrangea blooms can be ready in around two weeks. If they're still not mature, pour a little more water and give the plant more time.29

You can also hang the stems upside down individually or in small bunches in a cool and dry spot out of direct sunlight. Check these stems periodically for dryness. Placing hydrangea stems inside a plastic container and covering them with silica or white sand is another way to dry the flowers. After two to four days, shake them gently until clean.30