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Living with
Perennial Weeds
Published
in Organic Gardening Magazine - May 2009
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Is there any gardener who
hasn’t got, or had in the past, a problem with perennial weeds? Even the
smallest garden can be beset with couch grass and dandelions galore, with
ground elder or creeping thistle invading every border. In fact in a
small garden in a terrace with gardens on either side (that may not be
well cared for), the problem can be a nightmare. These plants can spread
through from neighbouring gardens on either side regardless of monumental
efforts to keep them out. How do we deal with these thugs? Can we
eliminate them, or do we need to learn how to cope with them and even
appreciate their tenacity? And it is always worth remembering that your
worst weed nightmare could be a wildlife magnet in disguise. However
I feel about the more ‘weedy’ plants in my garden that cause me problems,
I also have to admire them. To be successful, to reproduce and spread and
occupy a suitable habitat, is what a plant is designed to do. And
sometimes it is our interference that has contributed to the problem,
perhaps the addition of too much fertiliser, the removal of other plants
that then allow it free reign or even the elimination of its natural
predators that might have helped to keep it in check. In some situations
we may need to learn to live with a perennial problem rather than spend
all our time trying to fight it tooth and nail. |
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To the new gardener or allotment holder, the sight of a
plot brimming over with nettles or couch (called squitch in my home county
of Oxfordshire) is a daunting sight to say the least. But in some ways this
is the best situation to be in – here at the very start of your gardening
journey you can generally make a real impact on any major problems before
you have planned and planted. And if time is on your side, especially where
transient vegetables crops are concerned, it is possible to severely reduce
or even eliminate perennial weeds. Simply covering your plot with something
that excludes light for a time (black plastic sheeting, old carpet or a
specialist membrane) can be effective. Going down this route certainly
gives you the upper hand as once the majority of the offending plants have
gone the remnants may be dug out more easily. I often take this approach in
my garden, especially with nettles and docks although the latter with their
deep tap roots are incredibly tenacious. I generally use grass cuttings or
the hay from my meadow areas rather than plastic or carpet which I find very
ugly. These materials can also flap about if left through the winter (or
sometimes blow away completely in my windy garden!). Piling cuttings really
thickly onto an area of nettles, docks, creeping buttercup and unwanted
grass and other weeds, especially if left from autumn to spring, can very
effectively kill off the majority of these plants and loosen the soil
underneath to such an extent that digging out the remaining few roots will
be a pleasure rather than a chore. |
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This method will also help to enrich the soil beneath
with nutrients from the break down of the organic matter attracting
earthworms and other soil invertebrates. I have recently employed this
technique on an area of rough grass and weeds where I intend to make a new
pond – now easy to dig and no turf to remove. It also provided a winter
habitat for voles – the decaying hay is riddled with the runs of bank and
field voles which provide food for the local tawny owl, fox and kestrel.
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Digging of course is the option many organic gardeners
choose to take. In a small area this is entirely effective as long as one
is meticulous. It is also essential to dispose of the roots and rhizomes in
such a way as to ensure they don’t get the chance to grow and spread. I
tend not to compost roots of this kind, unless it is mid summer and they can
first be left in the sun to dry out completely. I put them into my green
wheelie bin (which otherwise remains empty all year round) from where they
make their way to the local biowaste digester. Like so many gardeners,
I seem to have spent my entire gardening life trying to deal with certain
perennial weeds, in particular nettles (on my first ever allotment) couch
grass and horsetail (my previous garden) and ground elder and bindweed in my
current garden. But whatever perennial weeds we have in our plots and
however we deal with them, they always have some value however obscure.
Every one of these difficult plants has wildlife value of some sort, whether
it be as a pollen or nectar provider, a larval food plant of moth, butterfly
or other useful insect, a seed provider for birds and small mammals or
simply as a plant in which to hide and shelter. It is worth remembering
that in any garden, as far as your local wildlife is concerned, any plant is
better than no plant at all. A weed is in the eye of the beholder - one
gardener’s nightmare could be another’s favourite wildlife attractant.
The bad guys – the worst
four to look out for: |
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Couch – Elytrigia
repens (Agropyron repens)
Couch, Twitch or Squitch
– this plant has plenty of local names reflecting its widespread
distribution. It loves newly dug soil and will rampage through all types
(including the heaviest clay) in what seems like a matter of days. The
rhizomes have a fiercely pointed tip which have been known to grow through
potatoes, concrete and even golf balls! Covering will kill off the
immediate plants but of course the rhizomes emerge unscathed and head off
through beds, borders and lawns with abandon. Best dug out where
possible.
Plus points – this grass is used by a wide range of moths and some
butterflies as a larval food plant. |
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Ground elder – Aegopodium podagraria
Jump About was one of the common names for this plant
and if you have this species in your garden you will know why! It spreads
easily from place to place and is perfectly happy in very poor soil. It was
introduced in the Middle Ages as a cure for gout. If ground elder had pink
or purple flowers we would probably all be growing it in difficult spots as
ground cover as its white flowers (it is a member of the carrot family and
the flowers resemble a smaller version of cow parsley) are actually very
pretty. The leaves are also quite attractive but the spreading nature of
the roots means that it gets in amongst other plants and is very difficult
to remove. There is a less invasive cream variegated variety of this plant
that is sometimes grown as ground cover.
Plus
points – the leaves make a tasty alternative to spinach and some moth
species use it as a larval food plant. |
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Horsetail
– Equisetum arvense
This plant is generally
thought of as a species that is a problem in wet soils but this is not
strictly the case. It likes to grow in compacted and poorly drained soils
and plagued my previous garden which was on a sandy soil. Like couch and
ground elder it is a plant that spreads rapidly underground by dark
rhizomes, but this species has a trick up its sleeve – the roots can happily
grow and spread at depths of one meter or more, making it virtually
impossible to remove by digging. It is an ancient plant related to the
ferns and reproduces by spores, so we do not even have the benefit of
flowers of any kind!
Plus points – sadly there are few but the stems
have been used in the past to scour pots and pans plus it is used as a
medicinal herb as a diuretic. Recent research has focused on its use in the
treatment of osteoporosis. It does produce thick ground cover for wildlife. |
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Nettles
– Urtica dioica
This familiar perennial weed is less of a problem to
cope with than some others. Generally nettles can be dug out fairly easily
– their fibrous root systems interconnect and digging them can be very
satisfying. Nettles prefer a soil rich in nitrogen so in a new garden or
allotment can be indicators of good fertile soil. In grassy areas nettles
rarely survive repeated mowing which is one way of eliminating them.
Plus points - nettles of course are the larval
food plant of the caterpillars of small tortoiseshell, peacock and red
admiral butterflies and many other small beneficial invertebrates thrive on
them including ladybirds. In the garden they are generally only used by
butterflies if they are in warm sunny spots.
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Other aggressive but wildlife
friendly perennials include:
Bindweed, dock, creeping thistle, dandelion, creeping buttercup and bramble.
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