Hydrangeas evoke images of grandmother’s garden. You may
recall the large, rounded shrubs and their heavy pastel flowers with fondness—or
distaste. Whether you’ve always loved hydrangeas or merely tolerated them, I
suggest you reevaluate the genus. Recent hydrangea introductions offer exciting
options for your garden.
While this review is by no means comprehensive, perhaps it
will whet your appetite to learn more about these late summer beauties.
macrophylla is the species name of both mophead and lacecap hydrangeas.
These shrubs possess medium-sized smooth leaves that are attractive as long as
the plant is healthy. Any nutrient problems will quickly manifest in the form
of chlorotic leaves.
To me, mophead hydrangeas add a lush, abundant feeling to a
garden. Their billowing form and heavy, rounded flowers make a luxurious
statement. Lacecap hydrangeas are
identical in leaf and form to their mophead sisters—only the flower differs.
Lacecap inflorescences are broad, flat-topped corymbs of tiny fertile flowers,
surrounded by a ring of sterile florets. I think lacecaps are slightly more
refined than mopheads, though they can be just as showy. Macrophyllas thrive
where they receive a few hours of sun daily. As long as your summers are mild,
they can take a half-day of sun or more. Conversely, all-day deep shade will
cause flowering to be sparse.
Macrophyllas are not drought-tolerant though an old,
established shrub will get by with less water. They prefer a slightly acid soil
because nutrients the plant needs are unavailable in very alkaline soils. A
high pH will result in the telltale chlorotic leaves. Furthermore, moving the
pH scale to either end of the spectrum can affect flower color. (See the
sidebar on page 13.) An average garden soil enriched with compost will make
your macrophylla thrive.
Macrophyllas can be imposing plants, reaching seven to ten
feet tall. Being deciduous, they can also leave a substantial void in the
garden come winter. I intersperse them within a mixed border that includes
evergreens to minimize gaps in winter.
Pruning H. macrophylla is considered tricky. Improper pruning is often blamed as
the culprit when gardeners complain that their hydrangeas don’t bloom. Many web
sites and references will tell you that you must prune your H.
macrophylla in late summer or it
will be ruined for the next season. I might get hate mail for this, but I
differ with most experts. To begin with, I’ve pruned my H.
macrophylla ‘Ayesha’ in late
winter/early spring for years, and have always had summer flowers.
The advice of hydrangea guru Glyn Church backs up my
experience. He suggests several approaches (and I paraphrase): a) For an older,
too-woody plant, remove two or three of the largest stems to the base of the
plant. Then trim the tops of remaining stems to just above a pair of large
flower buds. b) Prune the plant lightly overall, cutting back to just above the
largest buds (these are next summer’s flowers). Or, c) Remove all thin, spindly
growth, leaving the strongest stems. Cut back to the lowest set of big buds.
You will have fewer—larger—flowers with this technique.
I think the key with all these methods is to discern between
the big, fat flower buds higher up on the stems and the smaller leaf buds below
that go all the way to the base of the plant.
If this sounds like too much to think about, you’ll be
interested in the new reblooming macrophyllas that produce flowers early in the
season on old stems and again on new growth. Or, plant small varieties that
don’t need much pruning. Breeders continue to introduce smaller plants,
suitable even for container culture.
I grew up in a house that had H. arborescens ‘Annabelle’
dining room window. (We called it a snowball bush—a common moniker.) Every year
or so, we’d hack the daylights out of it and by the end of summer it was lush
and in full bloom.
H. arborescens is one of two North American natives, growing wild from the
Eastern Seaboard south along the Appalachian range. The species is extremely
hardy, more so than we’ll ever need in the maritime Northwest. And it’s
drought-tolerant, too, once established. H. arborescens enjoys full sun and decent drainage—other than that, it’s
not fussy about soil. Regardless of soil pH, it will always have white flowers.
Better yet, it can be pruned while dormant without fear of harming next
The only reason I can think of that more gardeners in our
region don’t grow this plant is that we don’t have to. Our mild climate allows
us to grow the macrophyllas that our Midwestern countrymen cannot.
The oakleaf hydrangea (so-called because its leaves resemble
an oak’s) is a lovely plant that should be more widely grown. This is the
second American native, growing further south than H. arborescens but also in the
The oakleaf has three strong seasons of interest. In spring,
its large leathery leaves emerge, quickly followed by green flower buds. Later,
large panicles of white flowers age to pink and as the weather cools the leaves
take on burgundy tones. A moderately large shrub, the oakleaf will reach five
to seven feet tall. It performs best in full sun with good fall color and
abundant flowering. It enjoys moderately rich, moist soil, but needs good
drainage or can suffer from root rot. It is not particular about soil pH.
Pruning consists of deadheading and removing dead wood.
Hydrangea paniculata ‘Grandiflora’ is the peegee hydrangea. The
inflorescences resemble an oakleaf hydrangea in that they are large and they
open white. These blossoms are dense, though, often bending the stems beneath
Paniculatas are cold hardy, easy to grow, and long-lived.
They are not particular about soil and grow best in full sun. Like H. arborescens, they bloom on new wood so can be pruned when dormant. It
isn’t necessary to prune every year, unless you’ve planted them in a place that
can’t accommodate their size. Peegee is the only hydrangea that is sometimes
trained to a standard. Breeding has brought renewed interest to this species,
offering a greater range of plant sizes and flower tints.
H. aspera is another multi-season plant. In spring its large, felted
leaves emerge followed by corymbs of tight brown fuzzy flower buds. In July,
the purple and white lacecaps open reaching eight or ten inches across. A large
crown of purple fertile flowers form a mass, surrounded by white sterile
florets. The flower is elegant and refined, the perfect adornment to this
distinguished plant. While the fall foliage is an unspectacular yellow, it
falls quickly, revealing shaggy peeling light-brown bark.
H. aspera is perfect for the back of the border, its deep green,
light-absorbing leaves providing a canvas for other plants. Grow hosta,
podophyllum, ferns, asarum, trillium, paris and other woodland treasures
beneath your H.
and you’ll be the envy of highbrow plant aficionados. H.
aspera grows in full sun or
partial shade, and blends impeccably in a woodland setting. Grow in average
garden soil, amended with compost and provide water as needed.
Don’t Forget the Climbers
No discussion of hydrangeas would be complete with mentioning
the climbing members of the clan. Hydrangea anomala subsp. petiolaris is fantastic growing up one of the enormous evergreens that
many Northwesterners have on their property. After a few years settling in,
this climber will eventually grow as far as you will allow it. In summer, it
produces elegant white lacecap flowers.
‘Moonlight’ is a hydrangea cousin that has beautiful mottled leaves topped by
white lacecap flowers in summer.