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How to grow Hydrangeas:
Hydrangeas are invaluable garden shrubs as they
possess the ability to combine structure, colour and interest within
one plant, filling their growing space with bountiful beauty. The
Hydrangea is able to thrive in a variety of situations, but prefer a
position in full sun or semi-shade, in fertile, moist, but well
drained soil, fully to frost hardy.
All hydrangeas are deciduous, and it's a welcome
sign of spring when the new green leaves begin to appear. Some
varieties maybe grown in the confines of large pots, which gives the
advantage of being able to move them to prominent positions around
the garden, once the flowers begin to open. The flowers last some
considerable time, they look especially spectacular out on the
patio. Larger growing species, some of which may become tree-like
with age, are best suited to the back of the border, or to light
woodland area.
Native to China, Japan, the Himalayas and both North and South
America, Hydrangeas have been naturalised in compatible climates
around the world. Their luxuriant dark green foliage offers a
striking background for other border plants.
The genus hydrangea is divided into about eight subsections, which
are further broken down into at least a dozen species and hundreds
of cultivars -- there are so many different kinds of hydrangeas that
it seems the exact number cannot be agreed upon. However the most
common types of Hydrangeas seen in nurseries today belong to only
five species: macrophylla, paniculata, quercifolia, anomala, and
arborescens.
Flower colours range from white through to pink, red and purple to
blue, but the blue flowers are only obtained on acid soil. It is
possible to alter the colour of some species by their growing
conditions. The blue or pink flower colour in these Hydrangeas is
dependent on the amount of aluminium and iron available to the
plant, more will result in blue, and less will give pink flowers.
The soil acidity determines the plant's ability to take up these two
minerals.
Many of the blue Hydrangeas need a pH of 6.5 or
lower to achieve their best blue colour and pink varieties need a
soil that is neutral (pH 7.0) or higher for their best pink colour.
Hydrangea varieties differ in their ability to utilize these
chemicals, hence some tend to be pink, others blue. This is only a
tendency and depending on soil pH any single variety can have a
range of colours. Some have flowers which change as the flowering
period progresses, they may appear pink at first, then begin to
change colour with some petals even taking on tinges of green, then
finally changing to blue.
Plant age also seems to affect flower colour and
some varieties may take 2-3 seasons after planting to settle into
the final stable colour. Adding aluminium sulphate to the soil prior
to budding to produce blue flowers; or by liming or adding
quantities of superphospate to the soil to produce pink ones may
control the flower colours. However it requires large quantities at
frequent intervals to control the colour. Therefore if your soil
conditions will not naturally maintain the desired colour, I believe
it to be scarcely worth the effort, particularly as they are all so
attractive in their own right.
DRYING HYDRANGEA BLOOMS: Hydrangea flowers make wonderful cut
flowers for the home; they can also be dried so that their beauty is
retained for a long period and they make wonderful floral
arrangements. Flowers that are to be dried must be cut late in the
season otherwise they fade and die before they have had the change
to dry out. The best species to dry are the "Mopheads" others are
less successful. Choose the stems you wish to dry and simply stand
them in a tall vase out of direct sunlight. Gradually they will
begin to dry out, becoming papery but retaining most of their
colours.
CULTIVATION: All Hydrangeas like deep, fertile, well-drained
soil in sun or semi-shade, they will require plenty of water in
warm, dry weather.
PROPAGATION: Generally speaking cuttings taken in the period
from June to August easily root. The best cuttings are from the ends
of non-flowering shoots with two or three pairs of leaves. Root them
in light sandy compost in a shaded area. Another successful way to
root the cuttings is to put them into a jar containing water, after
several weeks the roots will have grown. Great care must be taken
when placing them into compost so that the roots are not damaged.
PRUNING: With the exceptions of climbing hydrangeas such as
Hydrangea anomala ssp. petiolaris and the shrubby H. arborescens and
H. paniculata, which bloom on the current seasons growth, all other
hydrangeas bloom on the previous year's wood and are essentially
pruned in the same manner.
Pruning in the late summer to early autumn must
be avoided as it may encourage late growth that may not harden off
for the winter rendering the shrub vulnerable for cold and frost
damage. It is often said that no pruning at all is better than wrong
pruning and to some extent this is true. If hydrangeas are properly
fed and get sufficient water, they will bloom if never pruned at
all. True the shrub may become overgrown and a bit scraggly and not
nearly as attractive as a properly tended shrub, producing fewer and
smaller blooms but they will still produce flowers. Proper pruning
therefore is especially important with hydrangeas, for misguided
actions can spell disaster, resulting in few if any flowers during
the new season.
While a young hydrangea needs little pruning
beyond dead-heading, the more mature shrub may require the cutting
out of dead stems, the removal of brown leaves, and the occasional
errant vigorous stem that spoils the appearance of the shrub. Even
older hydrangeas may need a much more severe pruning. The best time
to prune is during a mild break in late winter weather in February
or March when the structure of the plant is quite visible and there
is no chance of injury to new shoots.
Cut any damaged stem down to the base of the shrub if it shows no
sign of rejuvenation. This severe pruning often results in a
proliferation of new shoots from the base of the plant. Any woody
stems particularly those in the centre of the shrub which do not
have signs of new bud growth should be removed to allow sunlight and
air currents to reach the centre of the plant.
The idea when pruning is to create a good
framework of stems, which will ensure that even when not in flower
the shrub still looks attractive and is able to produce healthy
foliage. While the new stems will not bloom during the current
season, they should put on a healthy display next season.
DEAD HEADING: The first form of pruning, especially for the
H. macrophylla, or Lacecap hydrangea cultivars, is deadheading, or
removal of spent blooms. There is some disagreement regarding the
appropriate time to carry out this action for some believe that
allowing the spent blooms to remain on the plant protects the buds
of next year's flowers that are present along the existing stem
during the winter. Some consider this a myth and take off the heads
in late autumn. Personally I prefer to retain the dried flower heads
allowing them to remain until spring when they are removed.
Deadheading is necessary as the spent blooms distract from the
appearance of the current seasons flowers. Simply cut the spent
blooms along with the flowering stalk, back to the uppermost pair of
new buds, taking care not to damage any of the new green shoots.
VARIETIES:
MOPHEADS / LACECAPS: There are two
distinct Hydrangea forms, which are referred too as Mopheads and
Lacecaps. Thy are both cultivars of the common hydrangea, H.
macrophylla, rounded shrubs with oval, mid-to dark green, deciduous
leaves. Their large, showy flowerheads are borne from mid-to late
summer.
MOPHEADS: Hortensias (H. macrophylla ) known as "Mop-heads,"
were named in honour of Hortense, the daughter of 18th century
botanist Prince de Nassau. Mopheads feature large domed, dense heads
resembling pom-poms, of mainly sterile flowers. Mopheads bloom in
solid masses, their clusters often so heavy that they cause their
stems to droop and bend especially when wet after rain.
LACECAP: Lacecap hydrangeas bear flat, open and rounded
flowerheads with centres of fertile flowers surrounded by outer
rings of sterile flowers.
Their centre flowers are small and inconspicuous,
however thee outer rings of their sterile flowers are larger and
quite striking. The name Lacecap is apt because the structure of
these flowers are reminiscent of the cap edged with an outer frill
worn by ladies during the Georgian period!
CONICAL HEADS: There is another flower head type similar to
the Mophead but unlike those domed heads the blooms are somewhat
longer with narrow, conical panicles. The flowers may be either
white or cream, often taking on tinges of pink or green
Many of my own favourite hydrangeas come from the paniculata group,
and bear the conical type heads. 'Brussels Lace', 'Floribunda'
and 'Unique'. Cultivars from paniculata are fast growing,
upright with flowers appearing during late summer and early autumn.
Flowers are mostly creamy-white, though some like 'Floribunda'
become pink-tinged as they age.
The two evergreen climbing hydrangeas, H. seemanii and H.
serratifolia require a sheltered position. After a slow start, the
growth of these plants increases in vigour, but normally require
little if any pruning. Prune only to confine them to their
designated area. Cut them back a bit if they are growing on a wall,
to encourage them to fully clothe the wall without projecting too
far out from the wall.
H.anomola ssp.petiolaris, the most familiar of the climbing
hydrangeas, requires little pruning at all. Once it is established
it is self-supporting and quite independent. The only pruning
necessary is that to confine the plant within its designated space.
Mature plants of H. anomola spp. petiolaris can climb to 75
ft. Removing dead flower heads close to the main stems promotes
future blooms.
Article
©MrsGreenFingers.co.uk 2005 No Unauthorised Distribution in full or
in part without express written permission.
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