Where
should I plant my tree peony?
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Tree
peonies are extremely hardy and will survive almost anywhere, in both
sun and shade. They prefer an airy, reasonably open situation as air
movement around the plant helps prevent fungal diseases like peony wilt.
However, avoid a completely exposed situation where flower petals could
blow away quickly and shorten the life of the flowers. These plants
begin to grow very early in the year and young developing buds can be
damaged by frost if exposed to early morning sunshine. Ideally, plant
your tree peony where this can't happen, i.e. a north, south or west
facing aspect.
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Soil
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Generally
speaking tree peonies prefer a fertile yet well drained soil, large
amounts of organic matter are not especially useful. They favor a neutral
to slightly alkaline soil. Clay, chalk or sand is fine as long as they
don't become too dry in the summer or very wet in the winter.
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Planting
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Dig
a large planting hole, incorporating some bone meal or a general fertilizer
into the soil. Add a small amount of well-rotted garden compost or manure
if you wish. We do not recommend peat as a planting medium because of
its acidity. Plant bare rooted tree peonies deeply. If your plant is
grafted (French, American and Japanese
hybrids), the graft union should be at least 3.5 inches below the
soil. This will encourage the tree peony (scion) to make its own roots
and basal shoots. Chinese varieties are propagated by division and don't
have a graft union and deep planting encourages new growth from beneath
the soil. Pot grown, rootballed or containerized specimens of all types
should be planted slightly deeper than the soil level in the pot. Water
them well after planting and during the following summer.
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Subsequent
Cultivation
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Usually
a tree peony will grow away producing large handsome leaves and often
some new shoots from the base. However, the main stem may not produce
a shoot from the tip. Depending on the size of the plant you buy, flowering
can happen any time from the first year to 4 years from planting. Sometimes
a newly planted tree peony will appear to make little growth, if any,
in its first season but all its activity happens underground. Providing
the foliage looks reasonably healthy, don't panic. This may just be
a 'settling in' period. Occasionally the main stem may die back a little.
Although this might be worrying, wait until the next spring when vigorous
growth should resume from the lower part of the stem or even from below
soil level. If your plant is
grafted, look out for suckers from the herbaceous rootstock and cut
these off at ground level. The foliage is quite different from that
of the grafted tree peony. Wait until you are sure these suckers are
from the rootstock before removing them, as your tree peony will also
produce basal shoots and these are what you want.
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Feeding
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Tree
peonies are heavy feeders but dislike large doses of fast acting nitrogenous
fertilizers. They respond well to a generous, early autumn top dressing
of blood, fish and bone, a slow release organic fertilizer. Its high
potash content encourages flowers to develop. A light sprinkling of
a general fertilizer can be applied in the spring if you wish.
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Pruning
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Tree
peonies respond well to pruning. You should aim for a broad, multi-stemmed
shrub of up to 4-5' in height, which will not need staking. Chinese
and American types have a naturally branching habit and will need
less regular pruning than the Japanese
and French types. In February, just as the growth buds are swelling,
trim off all the dead wood. You will often find that the new shoots
are coming from lower down the stem, leaving a small dead spur. Whole
branches will sometimes die. These should be pruned back to a live bud,
or to just above ground level. With a young plant, only remove dead
wood during the first two years to help get the plant established. Don't
be tempted to prune. After this if your plant forms a good shape, no
regular pruning is needed. However, if your plant has few stems and
is poorly shaped, then prune hard. You may see buds at the base of the
stem or shoots coming from below the soil. Prune back to these or down
to 6" or less from the ground. Even if you can't see any basal
buds, adventitious ones will form. The best time to prune is early spring,
although this may mean that you sacrifice some flowers in the coming
year. You can prune directly after flowering but re-growth is slower.
If you have, or inherit, an older tree peony, which has never been pruned,
it can be transformed and rejuvenated by applying this technique. It
is best to prune just one main stem each year, cutting it down to about
15 cms. It takes courage to do this, but is usually successful.
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Moving
a Tree Peony
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There's
no need to worry about moving even a large, mature tree peony. Just
move it during early autumn as you would any other woody deciduous shrub.
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Tree
Peonies in Pots
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Tree
peonies can be grown successfully for several years in a large container
(at least 12” diameter) and make very fine pot plants. When planting,
it is important to use a soil-based compost. Your plant should be grown
outdoors during the summer, autumn and winter. In the spring, when the
flower buds swell, you could move it into a cool conservatory to enjoy
the blooms but be sure to return the plant outside when the flowers
fall. Tree peonies must be outside in winter, as cold temperatures are
needed to form the flower buds.
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Peony
Wilt
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Tree
peonies rarely suffer problems from pests and are unpalatable to rabbits
and deer. The only disease you are likely to encounter is peony wilt.
This may appear in early spring, usually before flowering. Soft brown
lesions develop at the base of new shoots and buds. These wilt and become
covered with a characteristic gray bloom. As soon as any damage is seen
trim back the affected shoots to healthy wood. Spray the whole plant
with a systemic fungicide containing carbendazim. This should be repeated
at 10-day intervals until no further damage can be seen. The fungal
spores of peony wilt can over winter on old foliage so it's important
to pick up and burn old leaves in the autumn. With deep planting, good
hygiene and regular observation, although peony wilt may appear occasionally,
it rarely causes serious damage to a mature plant.
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