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Why Isn't My Hydrangea Blooming? & Hydrangea Demystified Download PDF (English)
Why Isn't My Hydrangea Blooming? & Hydrangea Demystified Download PDF (French)
Identify your hydrangeas -There are six main types of hydrangeas commonly grown in North American gardens.
Bigleaf - CITYLINE® Rio Hydrangea
Also known as ﬂorist’s hydrangea, hortensia, mophead, or lacecap hydrangea. Hydrangea macrophylla
Panicle - BOBO® Hydrangea
Also known as peegee hydrangea. Hydrangea paniculata
Smooth - INCREDIBALL® Hydrangea
Also known as Annabelle hydrangea. Hydrangea arborescens
Hydrangea petiolaris are hardy to USDA zone 4. Note: While we do not have hydrangea vine in our collection, we do have false hydrangea vine: Rose Sensation™ Schizophragma hydrangeoides.
Hydrangea serrata are
Proven Winners® varieties include: Tuff Stuff™ series
Oakleaf - GATSBY MOON® Hydrangea
Hydrangea quercifolia are
Proven Winners® varieties include: Gatsby™ series
Tips for Success:
- Moist but well-drained soil (hydrangeas will not tolerate wet feet – ever!)
- Some sun each day. Most people think of hydrangeas as shade plants, but they look and ﬂower best with at least 4 hours of sun, ideally in the morning. Panicle hydrangeas are the most sun tolerant, and can take full sun in northern climates.
- Plenty of water, especially as they are getting established. Hydrangeas have shallow roots, so they dry out quickly. A 2-3” thick layer of shredded bark mulch is a useful addition to any hydrangea planting.
It is the ways in which these six hydrangeas differ that make them confusing.
The trickiest thing about hydrangeas is that different types have different ﬂowering habits:
Panicle and smooth hydrangeas ﬂower on new wood (growth created in the current season). Flower buds on these hydrangeas form after the plant leafs out in spring, and open a few months later in summer. As a result, these plants ﬂower reliably each year, no matter how cold the winter was.
Bigleaf, mountain, oakleaf, and climbing hydrangeas ﬂower on old wood (growth created in the previous season). Flower buds on these hydrangeas begin to form in late summer and must remain undisturbed all through the fall, winter, spring, in order to ﬂower the following summer.
As a result, these plants will not ﬂower if:
- They are pruned. Pruning at any time will remove potential ﬂower buds.
- They are browsed by deer, which will eat the ﬂower buds.
- They are damaged by weather. Winter weather isn’t actually the problem; rather, it is in spring, when several days of warm temperatures are followed by a sudden freeze, that ﬂower buds are most likely to be damaged.
Reblooming hydrangeas, also known as remontant hydrangeas, are types of big leaf and mountain hydrangeas
that have the unique ability to ﬂower on both old and new wood. Even if the buds are damaged in winter weather,
the plant can still ﬂower on wood it produces that season. Reblooming hydrangea varieties include the Let’s
Dance series, and Tuff Stuff.
All hydrangeas undergo some color change as their ﬂowers age, but only big-leaf and mountain hydrangeas can change their color in a predictable, controllable way. It is not the pH of the soil that is responsible for this change – it is actually the presence of aluminum in the soil that does it.
- Certain varieties of bigleaf hydrangeas cannot experience color change – generally speaking, the more intense the color, the less likely it can change (Cityline® Paris hydrangea is a good example). Similarly, white varieties of big-leaf hydrangea will not change color.
- It is easier to change a hydrangea from pink to blue than from blue to pink, but both endeavors involve making chemical application in specific amounts at specific times. A soil test is necessary to determine the best course of action. If you decide to try to change the flower color, shop for products carefully and read all directions.
- Pennies or nails in the soil will not change the ﬂower color!
- Avoid pruning reblooming hydrangeas and those that ﬂower on old wood, altogether. Instead, site these hydrangeas appropriately so they do not need to be pruned, and choose varieties that do not get too big
for their space.
- New-wood ﬂowering hydrangeas can be pruned each early spring, just as the new growth begins to emerge.
Remove up to one-third of the height each year if desired to encourage vigorous new growth and strong stems to
support the ﬂowers.
- Hydrangeas do not strictly require regular pruning. They will grow and ﬂower well with nothing more than removal of spent ﬂowers and any dead wood each early spring.
Everything you want to know about Proven Winners Hydrangeas:
This handy chart makes it easier to compare the size, color, pruning needs and more.
Hydrangea Fun Fact
A hydrangea ﬂower consists of two different types of ﬂorets: the showy, papery ﬂowers are known as sterile ﬂorets and serve only to attract pollinators; the tiny fertile ﬂorets are where pollination and seed-set take place. Mophead hydrangeas are comprised mostly of sterile ﬂorets; lacecaps mostly of fertile ﬂorets.
Hydrangea Fun Fact
There are about 49 species of hydrangeas. Four species are native to North America, including smooth hydrangea and oakleaf hydrangea.
Hydrangea Fun FactBig-leaf hydrangeas and mountain hydrangeas are closely related and native to the same region of Japan, but mountain hydrangeas have
better bud hardiness because they occur in the mountains where conditions are harsher.