hydrangea serrata

How to Grow and Care for Hydrangea Serrata (Mountain Hydrangea)

Sharing is caring!

If you haven’t already, then you absolutely must consider learning how to grow and care for mountain Hydrangeas. They’re some of the most gorgeous and diverse plants of the hydrangea family. In fact, there are over two dozen cultivars of the mountain hydrangea plant alone.

This is the perfect guide for hydrangea lovers ready to add yet another variety to their garden.

If you’re not so experienced in growing hydrangeas (and maybe this is your first time), then don’t worry. This guide is suitable for all experience levels. We guarantee you’ll know the ins and outs of growing mountain hydrangeas after looking through our in-depth guide.

Continue reading to learn all about the beautiful mountain hydrangea (tea of heaven)!

What is the Mountain Hydrangea?

Known as Hydrangea serrata, or H. serrata for short, these plants are known for their flattened flower heads. They’re much more compact shrubs than their famous counterpart, H. macrophylla, and feature smaller leaves and flowers.

Flowerheads on this variety are characterized by small fertile florets in the center with sterile showy florets on the margins. Straight mountain hydrangeas bloom lace-cap flowerheads; however, different cultivars adapt or alter this quality. Flowerheads only grow to around 8” in diameter.

Like other hydrangeas, the flower of these plants changes color with soil pH levels. Higher acidity will bloom blue flowers, while alkaline soils will bloom pink flowers. These shrubs bloom in late spring or early summer and rebloom throughout the season.

Mountain hydrangeas are native to the moist and woody upland regions of Japan and Korea. However, these hydrangeas are well adapted to USDA zones 6b-9b, and hardy against cold climates. They are also deciduous shrubs that lose all their leaves during the winter months.

One defining characteristic of H. serrata is the leaf. Usually growing from 2-6” long and 2.5” wide, these deep green leaves make a nice contrast to the plant’s colorful flower head blooms. Furthermore, the leaves feature serrated edges, which helped create the “serrata” portion of its name.

hydrangea serrata

How to Grow Mountain Hydrangea

Now that you have more than enough information about H. serrata cultivars to choose from, we should move on to growing techniques for this relatively stocky shrub.

When it comes to learning how to grow hydrangeas, pruning is not a big concern for mountain hydrangeas; however, you should always be mindful of trimming away old wood. For all cultivars besides Tuff Stuff®, flowers bloom only on old wood, so cutting away stems will sacrifice future blooms.

You should be pruning away dead or damaged wood in the early spring. Or, cut away one-third of old wood before summer’s end and as close to a double-bud as possible. You can also shorthand prune flowers once they’re bloomed to encourage vigorous flower growth. 

Clean away debris affected by the winter months, especially branches that have fungal infections for mildew. Be sure to protect your hydrangeas from strong winds as well.

How to Plant Mountain Hydrangea

Planting these specimens is all about shade, soil, and moisture.

Though mountain hydrangea bushes struggle with extreme cold, they also cannot survive dry, hot climates. For southern gardeners, we suggest giving the shrub partial shade by planting it in places where only afternoon sunlight hits. For northern gardeners, full sun is highly recommended.

Moist and rich soil is also necessary for hydrangeas to grow strong roots and stems. Applying mulch around the planting area is a great way to trap moisture, ease soil temperature, and protect against weeds. A good layer of shredded bark, peat, or compost will do the trick.

While moisture is vital for mountain hydrangea, too much is harmful. Always plant your hydrangeas in well-drained soil to protect against root rot.

Caring for Mountain Hydrangeas

With your hydrangeas in the ground, you’ll need some care tips to promote gorgeous blooms for the coming season. Here are some basic techniques for watering, weeding, fertilizing, and defending your plant from pests or diseases.

Watering

Dry climates will require frequent summer watering to ensure the soil never dries out. Moderate moisture is the goal, so heavy watering is not needed. Mountain hydrangeas in cold and humid climates will require less watering and sun exposure to counteract soil moisture.

Weeding

If you keep your hydrangeas well mulched, then weeds shouldn’t be an issue. Routinely apply fresh mulch over the plant’s roots, but away from the crown, when the soil warms up in the spring.

Fertilizing

Fertilizing is necessary for all hydrangea and can help change bloom colors. However, all mountain hydrangeas should be fertilized once in the spring, so keep flower color in mind when selecting fertilizer.

For blue cultivars, apply acidic fertilizers to increase decrease pH levels. Fertilizers low in phosphorus (like 12-4-8) help encourage blue colors during the hydrangea’s next bloom cycle. If you prefer red cultivar, then using general-purpose fertilizer works just fine.

Incorporate dry fertilizer into the top 2-3” soil layer around the hydrangea and soak it in thoroughly.

Pests and Diseases

No pests pose severe problems for mountain hydrangea bush. However, aphids and slugs are common pests that all hydrangeas face. Practice essential pest control to counteract these garden nuisances.

These particular shrubs are susceptible to powdery mildew, bud blight, bacterial wilt, ringspot virus, grey mold, and leaf spot. Therefore, constantly monitor your hydrangeas, clearing and destroying dead or weakened branches with traces of those mentioned above. 

Types of Hydrangea Serrata

Since its time as a Japanese garden favorite, hundreds of cultivars have been created for the mountain hydrangea. While we won’t go too into detail on these Japanese cultivars, we felt it was worth mentioning some of the more popular ones.

Some famous Japanese H. serrata cultivars include:

  • Akishino Temari
  • Amacha Nishiki
  • Amagi Amacha
  • Beni
  • Beni-Gaku
  • Chishima
  • Hallasan
  • Shinonome
  • Shiro Fuji
  • Shiro-Tae
  • and many, many more!

These represent most mountain hydrangea out there, but not necessarily cultivars American gardeners can quickly get their hands on. For that, we’ve listed the H. serrata popular in North America today. Most of these cultivars were created relatively recently by gardeners who consider these shrubs “heirloom” plants. In other words, plants that “remind us of the garden heritage of our forebearers.”

H. serrata, ‘Annie’s Blue’

Hydrangea Serrata Magic Seduction® “Annie’s Blue” is a fairly recent cultivar that enriches the flowers’ blue color.

Like the usual flowerhead of straight H. serrata, Annie’s Blue bloom compact lace cap inflorescences. The flowerheads are blue or purple depending on the soil acidity and grow on strong stems that don’t bend with the flower’s weight. Ultramarine blue stamen clusters make up most of the lace cap, with light blue florets surrounding them.

H. serrata, ‘Blue Billow’

Much like Annie’s Blue, the Blue Billow cultivar features light blue, lace cap flower heads. However, what makes Blue Billow slightly different is the deep crimson color that the flowers develop over time. During the fall months, the plant’s foliage will turn into a beautiful bronzy burgundy that complements its aged flowers.

Blue Billow hydrangeas are more cold-tolerant than other serrata cultivars.

H. serrata, ‘Bluebird’

Bluebird mountain hydrangeas are somewhat like the Blue Billow cultivar. The Bluebird’s leaves do turn red in the fall, similar to the Blue Billow hydrangea. However, the lace cap flower heads never turn red, and the outer florets are white.

H. serrata, ‘Blue Deckle’

Blue Deckle is another blue lace cap cultivar that transitions flower color with time. This cultivar begins with light blue flowerheads that transition into sea-green and lilac-purple hues. Blue Deckle also features leaves that turn to bronzy red with purple tips in the fall.

H. serrata, ‘Diadem’

Dubbed the “crown jewel of the hydrangea serrata family,” this cultivar is characterized by light pink and light blue lace cap colorations. This cultivar will bloom much earlier than other hydrangeas and is also heat resistant compared to cold-hardy H. serrata cultivars.

H. serrata, ‘Miranda’

With usual tones of light blue and lilac-pink, H. serrata “Miranda” is best known for its dainty appeal. Atop yellow-green foliage sits lace cap flower heads fully extended on long upright stems, giving it a delicate attitude despite its hardiness. An additional quality of the dainty flower is occasional pale stripping over its petals.

Additionally, the cultivar’s foliage is resistant to mildew and water spots.

Other Tips for Growing Hydrangea Serrata

Some nifty tips for growing hydrangeas include manually controlling pH levels. We know that acidic fertilizers encourage blue coloration, but red coloration can be encouraged with limestone. Always follow instructions on the bag for applying limestone as too much will yellow new growth,

Do you have what it takes to grow your own? Of course you do! With the knowledge you now have, you can start picking, planting, and growing your own mountain hydrangeas today. Add these plants to add that extra splash of color your garden needs.

Don’t forget to see more varieties of hydrangeas you can plant.

References

References

Tennessee State University: The Beautiful, but Not-So-Familiar, Mountain Hydrangea – link

University of Delaware: Hydrangea serrata – link

University of Massachusetts: Growing Tips: Hydrangeas, Color and Fertilizing – link

Close

*image by sasimoto/depositphotos

Scroll to Top