to the tree?
A healthy tree in general cannot be harmed by ivy clinging to the trunk.
The clinging-roots do not burrow under the bark, do not draw nutrients
from the tree, do not strangle the tree. But compared to, say, climbing
hydrangea or clematis, there are some potential hazards from ivy,
especially if unrestrained.
Ivy can over add so much weight to a tree that it increases the
possibility of of breaking loose bark & limbs. If it is not restricted to
the trunk, but has spread out into the canopy, it increases the chance of
blow-down in high winds, & especially in stormy areas adds risk. Ivy also
increases limb loss in high winds. Ivy increases these risks by increasing
the tree's wind resistance. It is recommendable to remove at least any ivy
that climbs away from the trunk, as that which clings to the trunk per se
does not increase wind resistance.
Ivy that has spread into the canopy can out-compete the tree for sunlight.
Ivy can hide tree-killing infestations, funguses, & diseases that are
treatable if spotted in time, but won't be spotted beneath the ivy. Trees
that are already ill or near the end of their lives, but which might have
had a decade or so of attractive life left in them, may have their time
shortened by ivy, by harboring bacterial disease or by providing a haven
for an increasing number of insects, some of which are harmful to trees.
Ivy that is doing especially well in a tree can be an early sign that the
tree is sick, & can hasten the development of disease, but it is not the
cause of the sickness. Heavy infestation of ivy is to be regarded as
evidence that the tree is in a natural state of decline.
Though ivy does extremely well in shade, it in general only produces
flowers & seeds when in full sun, & so seeks to get out of the shade by
climbing trees. It is especially fond of climbing up dying trees, because
aging or sickly trees produce fewer leaves, permit more light through,
which the ivy likes. Often ivy is seen thick upon a dead tree & it can
look as though the ivy must've killed the tree, but the ivy was merely an
opportunist seeking to get more sun;
English ivy is an invasive competitor harmful to our native forests,
though only if it begins to flower & seed. In order to flower, parts of
the ivy must go through genetic change which occurs only in bright sun. An
undergrowth of ivy in deep shade rarely if ever goes through the
metamorphosis required to produce flowers then seeds which birds scatter
into native woodlands. But ivy that has reached the upper canopy of a tree
& is in full sun frequently develops upright "bushy" parts that poke
straight up out of the cannopy like trees on top of trees. This is he part
of the ivy that will flower, & will be too high up to keep them from going
to seed, & only then poses a threat to native woodlands. For this reason
all flowering ivy should be removed from ANYwhere in the garden, but won't
even be noticed in the tree canopy.
Of course, if you live in England where it grows native, this is not an
issue, as excess ivy in declining trees is one of the preferred habitats
for sundry species of birds, bats, squirrels, etc. In England it is
illegal to damage or interfer with bat roosts, including trees with lots
of ivy. But here in the northwest where ivy is not natural to the forests
it invades, programs have been undertaken to remove English ivy which
eradicates sensitive native species in its path, & many landscapers have
"taken the oath" never to plant what has become an invasive pest. Dwarf
cultivars & variegated forms of ivy are not invasive, but large-leafed
plain english ivy should not be planted or preserved.
-paghat the ratgirl
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
Paghat is DEAD ON. I hate seeing this stuff in trees. It is an obnoxious,
invasive weed that transpires a great deal of moisture out of the ground,
year round. It belongs in Europe IMO...preferably France. Mike.
Mike LaMana, MS
Heartwood Consulting Services, LLC
On 10 Aug 2004 06:57:09 -0700, email@example.com (Ira) wrote:
This has been discussed before. I asked an arborist this question,
and he said emphatically, "No!" I am allowing English ivy to grow up
a pine tree, so that the deer won't eat the ivy (as they do every
I have tried growing English ivy on a troublesome slope but each winter the
deer strip it clean and it takes a long time to recover. I have some
growing on tuteurs that flank my garage. I know that winter is almost over
when the deer get hungry enough to start eat that ivy.
They got mine also. It was a long, cold winter here without much snow.
They ate the bergenia and I thought it was gone. It has recovered nicely,
but I didn't get a single flower in the spring because not a single leaf
survived. I wish they would eat all my liriope because I have to cut it
back to the ground anyway each spring.
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