IVY on old yews - to leave or to remove?
By Tim Hills

Ivy out of control at Harbridge © Tim Hills
“Ivy had twisted up to the very summit, and looked well,
the lighter shiny green leaves among the dark of the needles. But
I realised that the ivy had to be stripped right off and out……even
up there, when you are in the wind and heavy among branches much
thinner than the wrist-thick ivy which strangles them……at
last the yew grows again visibly from the mealy base to the apex
of its pyramid. One feels that a resolution of evil has been accomplished.
Death has been destroyed. At first, it is true, when you have wheeled
away all the debris, the yew will look naked. By consolation comes
the first sunlight on the uncovered trunk….” Gardenage
(1952) Geoffrey Grigson

Ivy under control at Bettws Newydd © Tim Hills
A few strands of ivy on a yew bole is not a problem. It becomes
a danger when allowed to grow up into a tree and bush out. If allowed
to progress this far ivy may cause two problems, the weight of its
foliage and the shading out of the tree’s own leaves.
For those needing to make a case for the removal of ivy from an
old yew, the following may help.
Ivy “can smother the canopy and kill trees, so removing
the basal ivy stems
(in 20cm lengths to stop them re-grafting) will kill off the ivy
above in the
canopy”.
Russell Ball - Some Management considerations for our Ancient
Yews
“Ivy ……should be removed, as it can weaken the
tree’s system, and its weight makes the tree more vulnerable
to storm damage”.
Allen Meredith - Caring for Yews
“……in a gale a tree that is heavily laden with
ivy is like a fully-rigged ship, unable to lower its sails. Over
it goes!”
Jennifer Sandy - Richard Mabey’s Flora Britannica
“When clearing ivy from fallen trees I have found that
the weight of ivy exceeds the weight of the host.” N.J.Burrell
- Richard Mabey’s Flora Britannica
“The dead leaves can’t drop from the host and the
ivy will put its roots into the rotting debris.” Tree surgeon
Simon Russell - Richard Mabey’s Flora Britannica
“I spent several weeks climbing into the yew trees in
our churchyard and cutting down the ivy, which had such a grip
that in some cases I had to use a crowbar to remove it….It
had left deep weals where it was wrapped round the branches.”
R.Chilver - Richard Mabey’s Flora Britannica
One of England’s largest recorded yews used to grow in the
churchyard at Dibden, in Hampshire. The Saturday Magazine
of February 4th 1837 described the ivy filled yew (pictured below).
“Its hollow trunk still supports three vast stems, and measures
below them about 30 feet in circumference, a girth which, perhaps,
no other Yew-tree in England can exhibit.”
The engraving clearly shows that the tree was carrying a huge weight
of ivy on its split trunks and the article describes “….the
singularly large stems of ivy which had grown up against the interior
portions of the trunk. One of these ivy stems measures two feet
in circumference at the base, and after ascending seven feet, this
gigantic parasitic sends out fantastic limbs, which, entwining around
its antique supporter, had in many parts entirely overshadowed its
decaying branches”.
Although the article goes on to suggest that the tree was only held
up by the ivy, it is almost certain that the increasing weight of
ivy eventually contributed to its collapse. My thanks to Allen Meredith
for providing a copy of this 1837 document.

The Dibden Yew in 1837
When the health of a 500 or 1000 year old tree is threatened, the
ivy should first be cut and later carefully removed from its branches.
It should be borne in mind that ivy grows successfully on hundreds
of thousands of trees. Birds, bees and other insects will not be
deprived of food or habitat if ivy is removed from a few hundred
of these rare, ancient and irreplaceable specimens.
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