Hydrangeas are seen as an old-fashioned
plant, loved for their impressive foliage and big blooms in shades of blue,
white, pink and even green.
While colour is soil dependent,
hydrangeas thrive in cool, moist shade, and you would think they wouldn’t do well
here, but some are more heat and drought tolerant than others, and it’s
apparently possible to grow these spectacular plants here, particularly on the
north or south side of your home.
I have never grown these beauties, they
are something I have always considered a somewhat specialist plant, as it seems
a lot of expertise is needed to get such gorgeous displays blooming, and they
are not really a plant for the heat.
Having said that, I see gardens here
where they are obviously well established and people have managed to grow them
successfully, so I thought I should explore and find out what the trick is.
Keep in mind that even sun and heat
tolerant hydrangeas benefit from afternoon shade in the heat - too much direct
sun will wilt the leaves and stress the plant but using a temporary shade
structure might help. Also, they will all need plenty of our precious water
during hot, dry weather – sometimes every day.
So far, there are no truly drought
tolerant hydrangeas, although some are more tolerant of dry conditions than
others, and rich organic soil and a layer of mulch will help keep the soil
moist and cool.
Plants cool themselves by drawing water
from the roots, which then moves through the stems and out through the leaves,
which occurs at a faster rate during really hot conditions.
Smooth hydrangea (H.
This is native of the eastern US as far
south as Louisiana and Florida and therefore accustomed to warmer climates. It
reaches heights and widths of about 3 m and displays dense growth and
attractive greyish green leaves. The flowers in bud are green but bloom into a
bright creamy white, with some varieties being pink.
These shrubs bloom on new wood, so in
late winter or early spring prune them back close to the ground to encourage new
growth, plus remove any branches that are sick, dead or damaged.
Bigleaf hydrangea (H.
This is a native of Japan with shiny,
toothed leaves, a symmetrical, rounded shape and a height and width of 1-2m.
Bigleaf is divided into two flower types – ‘lacecap’ and ‘mophead’. Both are
among the most heat-tolerant hydrangeas, although mophead prefers a bit more
Mopheads are sterile, and will not get
pollinated, but will bloom on throughout the summer. The shrub’s ‘magic trick’
is that they can change colour - grown in acidic soil, it grows blue flowers,
grown in alkaline soil, the flowers will grow in pink (apparently the old story
of putting rusty nails in soil does make the soil acidic and turn the flowers
When pruning, do so right after the
shrub finishes flowering. The lacecap difference is that instead of growing
round clusters of showy blossoms, this hydrangea grows flowers that resemble
flat caps with frilly edges.
They produce showy florets, surrounded
by small flowers that look like closed buds, creating a lacey effect. These are
fertile and will attract pollinators.
Panicle hydrangea (H.
These are a pretty pink, also sun
tolerant, needing five to six hours of sunlight but won’t grow in full shade.
However, they won’t do well in intense, direct sunlight either. They reach
heights of 3-6m, sometimes more, although dwarf varieties are available
Oakleaf hydrangea (H.
These are hardy, heat tolerant
hydrangeas that reach heights of about 2 m. The plant is named for the oak-like
leaves, which turn reddish bronze in autumn.
The oakleaf is one of the best for
drought tolerant hydrangea shrubs; however, the plant will still need moisture
during hot weather.
Note that all hydrangeas are poisonous
to both us and to our pets, with skin contact causing dermatitis, rash or
irritation, as all the plant parts contain cyanogenic glycoside.
All in all, it seems hydrangeas are
tricky to grow, and getting the right spot with plenty of water seems to be the
key to successful growth.
Marilyn writes regularly for The Portugal News, and has lived in the Algarve for some years. A dog-lover, she has lived in Ireland, UK, Bermuda and the Isle of Man.