In an echo of the chicken versus egg debate, opinion is
divided among scientists on which came first, bees or flowering plants. They
are agreed, however, on the fact that by about one hundred million years ago,
bees were dodging dinosaurs to pollinate flowering plants. Since then, bees and
flowers have co-evolved. Flowers developed arresting colours, alluring
fragrances and shapes that would easily accommodate bees. Bees evolved special
body parts and body hair, becoming an unwitting third party in plants’
reproduction as they transported pollen stuck to their bodies from flower to
flower. In rare cases the flower/pollinator evolution has been so specialised
that only one insect can pollinate a plant. These tend to be plants whose
evolution was not affected by glaciation, for example the large red flowers of
the southern African Meneris tulbaghia
is pollinated by a single butterfly species.
For millions of years the flower/bee relationship evolved
without any outside interference but then we decided we could ‘improve’
flowers. We wanted larger petals, different colours and longer flowering
periods. As plant nurseries became increasingly commercial, the competition to
produce bigger, brighter and showier blooms became intense. In the process we
began to disrupt the flower/bee relationship. We bred plants to encourage
mutations of the flower shape that eliminated the pollen producing stamens. Often
these mutations, such as double flowers, made the nectaries inaccessible. Nectar and pollen were off the menu for bees
at these flowers.
The hunt for nectar and pollen became even more difficult as
we began to fill our gardens with exotic plants introduced to the UK by
intrepid Victorian plant hunters. Plants
from all corners of the planet began to be grown in British gardens.
Rhododendrons from the Himalayas, fuchsias from South America and gladioli from
South Africa,
among others, all became popular with British gardeners. Pollinated by the
birds, insects or mammals of their native land, the flowers of these plants
were often inaccessible to bees, or indeed any British native pollinators. Not
all exotic plants are no-entry zones for bees, however, as we will see later.
Despite the best efforts of plant breeders and importers,
there are still hundreds, if not thousands, of garden worthy plants that can
provide a feast for bees and other pollinators. By following some simple
principles, planting can be designed that is pleasing to the human eye and
provides generous nectar and pollen sources for bees.
Good planting design starts with what is called ‘structural’
planting. This is the planting that will give the garden shape, height and
definition, even in the depths of winter. Formal gardens often use evergreen
shrubs and hedges such as box or yew, perhaps clipped to a geometric shape, to
create this definition. In a bee friendly
garden this structural planting is ideally British native trees or shrubs. Many
of these are spring flowering and will create pollen and nectar sources early
in the season, when bees can struggle to find food. Double flowered varieties
should be avoided. A hedge of native shrubs starts flowering early in the
season as the white froth of blackthorn appears. The beautiful white blackthorn
blossom can appear as early as late February, often in a very cold period following
a false spring. These cold snaps are known as ‘blackthorn winters’.
A native hedge will then continue flowering almost
continuously until June when the native roses wind through the branches. It is
not only a fabulous smorgasbord for pollinators but also an excellent habitat
for other wildlife. The illustration
shows a native hedge used as a garden boundary, it makes a good screen as well
as providing lots of pollinator friendly plants.
While a native hedge will create a linear feature in the
garden that can enclose space, create boundaries or screen unsightly features,
a single specimen tree can be a focal point and introduce height into the
garden. Again, a British native is a good choice to cater for pollinators.
Trees such as the mountain rowan (Sorbus
aucuparia), crab apple (Malus
sylvestris) and wild cherry (Prunus
avium) are great all-rounders. Rowans and crab apples have the added bonus
of persistent fruit that will festoon the tree through winter as well as spring
blossom, providing food for birds. Take advantage of the plant breeders’ work
to choose a variety that contributes maximum interest to the garden; just steer
clear of double flowers! A good crab apple is Malus x robusta ‘Red Sentinel’. Some non-native trees such as the
Snowdrop Tree (Halesia carolina) are also good for bees.
Having ensured the garden has strong structural planting.
The next step is to fill in the spaces that have been defined by the structure.
This planting can be accomplished fairly easily with a selection of shrubs or a
more complex planting of flowering herbaceous perennials in beds can be planned.
If shrubs are used,
they should be chosen to provide a long succession of flowers throughout the
season. Again, British natives are a good choice but, depending on flower
shape, some exotic shrubs can also provide for pollinators. When planning infill planting it is worth
creating a planting calendar to check you have covered as many months as
possible.
Check mature heights and spreads when choosing shrubs. A
common mistake is to plant shrubs too closely together so they do not have the
space to grow into healthy plants. This does mean that planting can look a bit
lean in the early years but this can be overcome by planting annuals such as poppies,
cornflowers or clarkia. Alternatively, relatively fast-growing, sacrificial
shrubs such as lavender can be inter-planted between the long-term planting and
then removed as needed. Groundcover planting such as periwinkle or ivy can also
soften the area around newly planted shrubs. Ivy is an excellent choice as the
flowers continue to provide bee food late into the season.
Planting swathes of perennials to ‘froth’ through the
structural planting can create a bit more drama and spectacle than
shrubs. It does take more planning and maintenance, however, so it is not an
approach to be taken lightly. That said, if you avoid the more high maintenance
perennials such as delphiniums you can keep the work to a reasonable level.
Bees like to blitz a small area of flowers when collecting
food. Large groups of the same perennial species planted together provide handy
nectar bars that will soon attract large groups of bees as the news of a good
food source spreads around the hive. Odd numbered groups of plants, 7, 9 and 11
are pleasing to the human eye. Plant in thin drifts of the same species that
thread their way through the border. Ideally, place the later flowering
perennials towards the front of the border. This means that as plants go over
fresher blooms appear, concealing the dying flowers.
Bees do not see flowers as we do. They have compound eyes
which means that objects appear pixillated; they do not see shapes as we see
them. Bees seem to favour spherical flowers and this may be because their
vision finds a sphere easy to distinguish. Their colour vision is also
different from humans. We have three
colour receptors that allow us to see blue, green and red. Bees also have three colour receptors but
they see UV, blue and green. Many bee pollinated flowers have UV
‘landing-strip’ markings to guide bees to the nectaries. Besides their UV
vision, bees can also detect the polarisation of light. Air molecules in the atmosphere scatter
photons to create a pattern of polarised light arranged around the sun. This
helps bees to navigate by the position of the sun even when the sky is
cloudy. So plants with blue/purple
flowers are visible, and attractive, to bees. Observation has revealed that
bees also prefer yellow flowers and this may be because yellow is a pale colour
that contrasts well with the green background of leaves. Many yellow flowers also have UV markings,
invisible to us, but clear signposts to bees.
A well designed
garden has open, flat areas as well as areas of planting. The open areas act as
a respite to the profusion of planting. Ponds work well as open areas and will
bring light and reflection into the garden. A well designed pond can be a great
habitat for wildlife. The Pond Conservation Trust web-site, www.pondconservation.org.uk
has lots of good advice on building
ponds.
Lawns also create open space in the garden and British
gardens are famous for their lush, rain-watered lawns. A traditional
striped-green lawn is a mono-culture, however, and not a great source of
bio-diversity. Bees prefer a flowering lawn, and
many people agree with them. A flowering
lawn does not have to be cut as regularly; indeed frequent cutting will stop
the flowering. Lionel Smith of Reading
University hit the headlines in 2013
when he planted a grass-free flowering lawn in a London public park. His blog makes
interesting reading, blogs.reading.ac.uk/grass-free-lawns/rethinking-the-traditional-grass-lawn.
Emorsgate Seeds, wildseed.co.uk, sell a Flowering Lawn Mixture that includes
wildflowers that respond well to regular mowing. Of course, the ultimate flowering lawn is a
meadow. If you have the space, and it probably does not need to be as large as
you think, a meadow is a great food source for bees. Another opportunity for
introducing more flowers into the garden is to install a green roof on your
garden shed. They are an attractive alternative to traditional shed roofs and
can be more effective insulators.
Plants that are good food sources are only half the story
when it comes to a bee friendly garden. We have an imperfect understanding of
how pesticides, and other garden chemicals, affect food crops and gardens in
general. Do not use them if you want to avoid the risk of contaminating the
garden ecosystem, either in the short or long-term.
So far we have discussed how to achieve a garden that is a
haven for bees. It is worth remembering that bees evolved in a wild ecosystem
of complex connections that link the smallest soil organism to the top
predators. We are still learning how
these connections work. While we can fine-tune the garden to suit bees, we
should not lose sight of the bigger picture.
A garden that supports wildlife and the local ecology in all its
diversity benefits everyone, including the bees. The RHS and Wildlife Trusts
web-site www.wildaboutgardens.org.uk
has good advice about wildlife gardening in general. A garden that is beautiful
for humans and a great habitat for wildlife are not incompatible. All it needs
is a bit of planning.
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