Everyone has their favourite wildflowers.
Mine include showy species such as bluebells, meadowsweet,
cowslips and scabious as well as more subtle beauties
especially moschatel, water crowsfoot and eyebright. If however, I were
choosing my favourites from the point of view of bringing
wildlife to my garden, then my first choice would always be
the knapweeds. Robust plants with pink, blue or purple
flowers, the knapweeds and their close annual relative the
cornflower, must be amongst the very best of plants for
encouraging garden wildlife. The ease with which they will
adapt to almost any garden situation makes them really
special.
The knapweeds (species of Centaurea) belong to
the daisy or Compositae family so a large part of their
wildlife attracting ability lies in the fact that each flower
head is made up of hundreds of small florets – tiny individual
tubular flowers brimming with nectar. If you observe a
butterfly or bumblebee on a knapweed flower you will see that
it spends a great deal of time probing its long tongue again
and again into the tiny separate flowers, moving methodically
over the flower head. It’s a little bit like visiting a
supermarket for all your food, rather than many individual
small shops! This means that the insect saves a great deal of
energy by staying in one place for some length of time,
although this method of feeding has the potential to increase
the risk of predation. That risk must be worth taking
however, as anyone who has watched a clump of knapweed flowers
will have noticed.
We have one annual wildflower member of this
group – a flower with a hue so intense that it has a colour
named after it. Mention ‘cornflower blue’ to anyone and the
phrase will immediately conjure up the true pure blue that is
characteristic of this wonderful flower. Sadly lacking from
our countryside now, the cornflower was once a common sight in
cornfields together with corn poppy, pheasants eye, corn
marigold and corncockle, all of which have suffered at the
hands of weed free agriculture. These annual flowers are easy
to grow in our gardens in a sunny spot, either together in
swathes of gorgeous mixed colours, or in single species
groups. Sow this month by scattering the seed onto the
surface of weed-free, turned and raked soil, and press them
gently into the soil surface with hands or feet.
The cornflower has great wildlife value and is
especially good for attracting the smaller butterflies to the
garden. Common blue, small copper, the skippers and the brown
argus, a species found increasingly in gardens in the south,
all seek out this flower for its nectar. Honeybees,
bumblebees and hoverflies also visit it for pollen and
nectar. If it is one of the few butterfly nectar sources in
your garden (or on your allotment – it makes a wonderful cut
flower as well as encouraging beneficial insects) it may also
attract the small tortoiseshell and other larger butterflies.
Easy to grow, a stunning colour and a self-seeder too. There
are many cultivated varieties in a range of colours if you
prefer, some shorter and more manageable than our native
flower and all seem to be good at bringing insects to the
garden.
Throughout Europe the knapweed group is
represented by a range of perennial species, some more akin to
the closely related thistles than our familiar British
plants. A few of these are now naturalised in our countryside
and may be worth trying in your garden if seeds or plants can
be located. The yellow star-thistle is one, its pale lemon
knapweed head providing a pleasing contrast to our own purple
flowered species. This plant is pollinated by bees as is
another non-native interloper, the perennial cornflower, a
common cottage garden plant sometimes occurring as a garden
escape. I always find a place for this plant in a border
somewhere, as much for its heady scent of coconut (reminiscent
of tropical holidays!) as its attraction to bumblebees.
Common
and greater knapweed are plants that are well known to most of
us who appreciate the countryside and wildflowers. Often seen
on roadside verges, in waste places, on railway embankments
and cliff tops, these species are an important component of
the nectar supply for bees and butterflies in natural
habitats. Both were once common in hay meadows, a habitat in
short supply now. If you have a small garden meadow or intend
to create one, make sure that you include one or both of these
plants to ensure a good nectar supply for summer butterflies
and bees, as well as long lasting colour into September.
Common, lesser or black knapweed is the coarser
of the two, having tighter, thistle–like purple flower heads
resulting in its other common name of hardheads. In the
garden it will grow to 60 cms or so, its tough stems resisting
almost any gale, making it useful for a windy spot. The dark
green leaves are rough to the touch and are pale and felted
with hairs beneath. Many insects will visit the purple
flowers which bloom from June to September, making it a great
plant to include in a late summer border. Once the flowers
are over, this plant, like all its close relatives, produces a
seedpod full of large nutritious seeds, which, much like
teasel seeds, will bring goldfinches from miles around. It
will self seed gently (few seeds ever escape the finches) so
it never becomes a problem in the garden. In a meadow it is a
long lasting perennial, surviving for many years.
Greater knapweed is similar to common to the
untutored eye, and the two can easily be confused. Generally
though (but not always) common lacks the distinctive ray
florets – the pretty feathery bits around the edge of the
flower head which give greater knapweed a more shaggy
appearance. It is also a more pinky purple to my eye and the
leaves are more dissected. In truth it doesn’t matter which
species you grow as long as you manage to find true native
stock. They are equally brilliant at attracting bees,
butterflies, hoverflies and goldfinches. To some, greater
knapweed is the prettier plant and there are few more
wonderful sights in mid summer than a clump of this wildflower
covered with small tortoiseshell, peacock or marbled white
butterflies. In my garden last summer, the visiting clouded
yellows found a rich nectar supply in both greater and common
knapweed in my wildflower meadow.
The perennial knapweeds will germinate without
any kind of pre-treatment, needing no period of cold weather
to break their dormancy. The seedlings do however appear
rather erratically, so sow in spring in small seed trays, cover
lightly with grit or a fine layer of compost and be prepared
to tease the little plants gently from the tray as they
germinate, moving them into small pots or plugs. They are
robust seedlings, quickly producing a good root system and
they transplant easily.
If you are relatively new to growing
wildflowers in your garden you could do no better than
starting with the knapweeds. Easy to germinate and grow,
robust, suitable for border, meadow or wild corner, plus
brilliant for wildlife – there is no better place to start
your wildflower collection. |
