Not sure why your hydrangea isn’t flowering? Want to know when and how to prune it? These are all good questions, but no one can answer them correctly until they know what kind of hydrangea you have. This post will help with your hydrangea identification. It won’t provide cultivar names but it will identify the type of hydrangea.
It’s always a good idea to write down plant names because they make it easier to find the right cultural information later on. But life happens and it is quite common for people to lose the name of a plant.
There are several types of hydrangea and they don’t all take the same growing conditions. The type is based on the plant genetics – what species was used to develop the plant. Here is a brief list of the types that will be discussed in this post.
Macrophylla hydrangea have been bred using mostly Hydrangea macrophylla and Hydrangea serrata. Its common names include bigleaf hydrangea, French hydrangea, lacecap hydrangea and mophead hydrangea. In warmer climates where it does well, this is a very popular hydrangea because of its blue flowers. It also produces white, pink and purple flowers. The term macrophylla means large or long-leafed.
The smooth type has been bred using Hydrangea arborescens. It is commonly called smooth hydrangea, snowball hydrangea or Annabelle hydrangea. The term snowball comes from the fact that this type has the largest white snowball like flower heads. The other common name, Annabelle, shouldn’t be used because it makes people think that all smooth hydrangeas are Annabelles, which they aren’t. If you want to talk about a certain Hydrangea arborescens, you should only use the cultivar name, Annabelle.
This group of plants has Hydrangea paniculata in its genes. The common name, panicled hydrangea, refers to the shape of the flower head. Instead of being round it is cone shaped.
Historically, the most popular cultivar in this group is called Hydrangea paniculata ‘Grandiflora’. The name was shortened to PG hydrangea, using the first letters of paniculata and grandiflora. This plant became so popular that some people incorrectly refer to all paniculata types as PG hydrangeas. This leads to a lot of confusion. A plant that is is labeled as PG may or may not be Grandiflora. You never know what you are getting with a PG.
Hydrangea petiolaris and Hydrangea anomala are very similar species, that are known as the climbing hydrangeas. H. petiolaris is much more popular in the garden than H. anomala.
The oakleaf hydrangea, or oak-leaved hydrangea is Hydrangea quercifolia. A number of cultivars exist and it is easily identified by its leaves.
The following Hydrangea Identification Process has been split into two sections. The first part (the green part) is meant to help you recognize a hydrangea even if you don’t know much about its flowers. This is very useful if you are trying to figure out why your plant is not flowering.
The second section (blue section) works through a process of identification using flowers. You can use this section to confirm the ID you made in the first section.
Start with the section called “Identify by Plant Characteristics”. Work your way through this section until you get an ID. Then skip the rest of the section.
Read the section called “Identify by Flower Characteristics” to make sure you got the ID right if you know what the flowers look like.
The following process works most of the time. There are always exceptions in the world of plants, but it’s not likely that yours is one of them. If you do have an exception, let me know about it in the comments.
Hydrangeas are a popular flowering shrub that come in a variety of types and colors. Knowing what type of hydrangea you have is key to properly caring for it and getting the most blooms. Here’s a guide on how to identify the different types of hydrangeas based on visual characteristics.
Look at the Leaves
The leaves can provide some of the best clues to identifying hydrangea types.
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Oakleaf hydrangea – Leaves are distinctly lobed and resemble oak leaves. This is the easiest type to identify.
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Panicle hydrangea – Leaves generally have 3-5 lobes and are somewhat rounded. They are medium green in color.
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Bigleaf/French hydrangea – Leaves are oval or heart-shaped with serrated edges. They are thick, dark green and somewhat glossy.
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Smooth hydrangea – Leaves are more rounded and have a slightly fuzzy texture They are medium to light green in color
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Climbing hydrangea – Leaves are heart-shaped and have serrated edges They resemble bigleaf leaves but are smaller
Examine the Flowers
The flowers provide more clues to the type of hydrangea:
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Panicle hydrangea – Flowers are cone-shaped panicles ranging from white to pink.
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Bigleaf/French hydrangea – Two types of flowers occur on these. Lacecap flowers have tiny fertile flowers surrounded by showy sterile flowers. Mophead flowers have all showy, sterile flowers. Color ranges from pink, blue or purple.
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Smooth hydrangea – Flowers are round, white snowballs.
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Oakleaf hydrangea – Flowers are cone-shaped panicles of white flowers that turn pinkish as they age.
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Climbing hydrangea – Flowers are flattish clusters of white fertile and sterile flowers.
Look at the Growth Habit
The overall growth habit and structure provides more clues:
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Climbing hydrangea – A vine that climbs up structures or trees.
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Panicle hydrangea – A multi-stemmed shrub ranging from 3-6 feet tall in most varieties.
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Bigleaf/French hydrangea – A coarse-textured shrub that grows 3-6 feet tall.
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Smooth hydrangea – A rounded, dense shrub that grows 3-5 feet tall.
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Oakleaf hydrangea – A coarse shrub that can reach 6-8 feet tall and wide.
Consider the Petiole Length
The petiole is the small stem that attaches the leaf to the main branch. Petiole length can help distinguish between bigleaf and smooth hydrangeas:
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Bigleaf hydrangea – Petioles are short, generally less than 1 inch long.
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Smooth hydrangea – Petioles are longer, over 1 inch in length.
Look for Natural Habitat Clues
Knowing the native habitat of the different hydrangeas can provide more clues:
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Smooth hydrangea – Native to the eastern United States. Often found on streambanks and slopes.
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Oakleaf hydrangea – Native to the southeastern United States. Grows naturally in woodlands.
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Climbing hydrangea – Native to Asia. Grows on forests edges and climbs up trees.
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Panicle hydrangea – Native to Asia. Grows in mountain ravines and slopes.
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Bigleaf/French hydrangea – Native to Japan. Found growing along streams and in forests.
Consider the Bloom Time
The timing of blooms provides another distinguishing characteristic:
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Bigleaf – Blooms in summer on previous year’s growth.
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Panicle – Blooms in mid to late summer on current year’s growth.
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Oakleaf – Blooms in late spring on previous year’s growth.
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Smooth – Blooms in early summer on current year’s growth.
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Climbing – Blooms in early summer on previous year’s and current season’s growth.
Key Takeaways
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Look at the leaf shape, flower characteristics, growth habit, petiole length, natural habitat, and bloom time.
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Oakleaf hydrangea is easy to identify by its lobed, oak-like leaves.
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Bigleaf and panicle are two of the most commonly grown hydrangeas.
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Knowing the type of hydrangea is key for proper care and maximizing blooms.
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When in doubt, seeking advice from a local nursery can help properly identify mystery hydrangeas.
Properly identifying your hydrangeas takes some time and observation. But once you know what type you have, you’ll be on your way to growing beautiful, flowering hydrangeas in your garden.
Identify by Flowers Characteristics
The above traits make it easy to tell the difference between climbing and oakleaf hydrangea, so they will not be discussed in this section.
Number of Leaves per Node
A node is the point on the stem where one or more leaves are attached. The younger, smaller leaves at the stem’s tip grow in a different way, so look at the older, bigger leaves on the stem. Look at all the stems since the number of leaves can vary from stem to stem. Young paniculatas and poorly grown ones may not have 3 leaves.
- It is a paniculata type if at least one node on the plant has three leaves coming out of it.
- Move on to Petiole Length if none of the nodes have three leaves.
A petiole is the short stem that connects the leaf to the main stem. Check the length of the petiole on some of the older leaves. Ignore the smaller leaves at the tip of the branch since the petiole there is still growing.
- The type is likely arborescens if most of the older petioles are longer than 1 inch.
- Most of the older petioles should be less than an inch long to tell what kind of plant it is.
How to Identify Your Hydrangea // Garden Answer
How do you identify a hydrangea without knowing its flowers?
The first section (green section) has been designed so that you can identify an hydrangea without knowing anything about its flowers. This is very useful if you are trying to figure out why your plant is not flowering. The second section (blue section) works through a process of identification using flowers.
What are the different types of hydrangeas?
There are several well-known species of hydrangeas: Hydrangea macrophylla, often referred to as bigleaf hydrangeas, come in two forms: mophead with large, round flower clusters, and lacecap with flatter blooms. Hydrangea quercifolia, known as oakleaf hydrangeas, are recognizable by their oak-like leaves and white cone-shaped flower clusters.
What color are hydrangeas?
Hydrangeas are beautiful bushy deciduous shrubs with large, colorful, showy flowers and large bright to dark green leaves. Hydrangea flowers bloom in shades of blue, lavender, white, pink, red, green, and purple. The bigleaf hydrangea ( Hydrangea macrophylla) is the most popular of these flowering bushes.
What do hydrangea leaves look like?
The shape and form of hydrangea leaves depend on the hydrangea type and cultivar. Here are the types of hydrangea leaves: Bigleaf hydrangeas leaves are thick and glossy with serrated margins and grow up to 8” (20 cm) long. Panicle hydrangeas have narrow, dark-green fuzzy leaves that grow up to 5” (12 cm) long.