butterflies – Cabot Institute for the Environment blog

A bumblebee visits a blooming honeysuckle plant.
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Pollinators are struggling to survive in the countryside, where flower-rich meadows, hedges and fields have been replaced by green monocultures, the result of modern industrialised farming. Yet an unlikely refuge could come in the form of city gardens.

Research has shown how the havens that urban gardeners create provide plentiful nectar, the energy-rich sugar solution that pollinators harvest from flowers to keep themselves flying.

In a city, flying insects like bees, butterflies and hoverflies, can flit from one garden to the next and by doing so ensure they find food whenever they need it.
These urban gardens produce some 85% of the nectar found in a city. Countryside nectar supplies, by contrast, have declined by one-third in Britain since the 1930s.

Our new research has found that this urban food supply for pollinators is also more diverse and continuous throughout the year than in farmland. Everyone with a garden, allotment or even a window box can create their own haven for pollinators. Here are tips on what to plant for each season.

Three people in wellington boots work on raised beds in a garden. — Community gardens, allotments, even window boxes can sustain pollinators throughout the year.
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What to plant in spring

The first queen bumblebees emerge from winter hibernation in February and March. They need food straight away.

At this time of year nectar-rich plants are vital energy sources for warming up cold flight muscles, with pollen providing the necessary protein for egg laying and larval growth. In early spring much of the countryside is still bleak and inhospitable.

Gardeners can help by planting borders of hellebore, Pulmonaria and grape hyacinth. Trees and shrubs such as willow, cherry and flowering currant are also fantastic for packing a lot of food into a small space.

A bee on a willow flower — Willow in bloom.
Ira Kalinicheva | Shutterstock

What to plant in summer

In late spring and early summer, pollinators have more food available – but there is also more competition for it. So it is crucial to ensure you have a diverse array of different flowering plants. This will guarantee there is attractive and accessible food to suit a wide range of insects and provide them with nutritionally balanced diets.

A great assortment of plants, including honeysuckle, Campanula and lavender, can provide floral resources in summer. Mowing the lawn a little less often will help too, giving the chance for important so-called weeds, such as clover and dandelion, to bloom.

Ivy in bloom with a red admiral.
Seepix | Shutterstock

What to plant in autumn

By late summer and autumn there are fewer species still flowering in gardens. A handful dominate the nectar supplies, particularly Fuchsia, Salvia and Crocosmia.

For many pollinators, however, these flowers are entirely useless. Their nectar is hidden away down a tube, only accessible to insects with long tongues, such as the garden bumblebee.

This means solitary bees and hoverflies may need to find other sources of food. The gardener can help by prioritising open and accessible flowers. Opt for species such as ivy, Sedum, Echinacea and oregano.

What to plant in winter

Few pollinators are still active in winter. Most species die off leaving the next generation behind as eggs, larvae or pupae.

But bumblebees and honeybees remain in flight, taking advantage of the warmer climate and winter flowers that cities can provide. By vibrating their wings, bumblebees can warm up to forage in temperatures barely exceeding freezing point, but they need a lot of energy-rich nectar to do so. If you want to attract bees into your garden during the winter some of the best options are Mahonia, sweet box, winter honeysuckle and the strawberry tree.

Yellow Mahonia on a frosty morning. — Mahonia on a frosty morning.
Sally Wallis | Shutterstock

Urban gardens are small and numerous, with hundreds or even thousands packed into a single square kilometre of a residential neighbourhood. Each gardener is different, with individual preferences of what to plant, how regularly to mow the lawn and even how to decide what constitutes a weed.

This results in an enormous variation from garden to garden in the quantity of nectar, the timing of its production and the types of flowers producing it. But there is always room for improvement. Some gardens provide pollinators with hundreds of times less nectar than others.

So keep yours well stocked with nectar and free from toxic pesticides. You’ll be amazed by the impact you can have.

This blog is written by Caboteers Nicholas Tew, PhD Candidate in Community Ecology, University of Bristol; Jane Memmott, Professor of Ecology, University of Bristol, and Katherine Baldock, Senior Lecturer in Ecology, Northumbria University, Newcastle

This article is republished from The Conversation under a Creative Commons license. Read the original article.

An easy win

Urban areas are a complex mosaic of different land uses and habitats. We surveyed pollinators in allotments (also known as community gardens), cemeteries and churchyards, residential gardens, public parks, other green spaces (such as playing fields), nature reserves, road verges, pavements and man-made surfaces such as car parks or industrial estates.

Perfect for pollinators.
Shutterstock.

Our results suggest that allotments are good places for bees and other pollinating insects, and that creating more allotments will benefit the pollinators in towns and cities. Allotments are beneficial for human health and well-being, and also help boost local food production.

In the UK, there are waiting lists for allotments in many areas, so local authorities and urban planners need to recognise that creating more allotment sites is a winning move, which will benefit people, pollinators and sustainable food production.

Good tips for green thumbs

We also recorded high numbers of pollinating insects in gardens. Residential gardens made up between a quarter and a third of the total area of the four cities we sampled, so they’re really a crucial habitat for bees and other pollinators in cities. That’s why urban planners and developers need to create new housing developments with gardens.

But it’s not just the quantity of gardens that matters, it’s the quality, too. And there’s a lot that residents can do to ensure their gardens provide a good environment for pollinators.

Rather than paving, decking and neatly mown lawns, gardeners need to be planting flowers, shrubs and bushes that are good for pollinators. Choose plants that have plenty of pollen and nectar that is accessible to pollinators, and aim to have flowers throughout the year to provide a constant supply of food. Our research suggests that borage and lavender are particularly attractive for pollinators.

Now that’s a happy bee.
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Often plants and seeds in garden centres are labelled with pollinator logos to help gardeners choose suitable varieties – although a recent study found that that ornamental plants on sale can contain pesticides that are harmful to pollinators, so gardeners should check this with retailers before buying.
Weeds are important too; our results suggest that dandelions, buttercups and brambles are important flowers for pollinators. So create more space for pollinators by mowing less often to allow flowers to grow, and leaving weedy corners, since undisturbed areas make good nesting sites.

An urban refuge

Parks, road verges and other green spaces make up around a third of cities, however our study found that they contain far fewer pollinators than gardens. Our results suggest that increasing the numbers of flowers in these areas, potentially by mowing less often, could have a real benefit for pollinators (and save money). There are already several initiatives underway to encourage local authorities to mow less often.

Roundhay Park in Leeds: not a flower in sight.
Shutterstock.

Ensuring there are healthy populations of pollinators will benefit the native plants and ecosystems in urban areas, as well as anyone who is growing food in their garden or allotment. Towns and cities could act as important refuges for pollinators in the wider landscape, especially since agricultural areas can be limited in terms of the habitat they provide.

It’s crucial for local authorities, urban planners, gardeners and land managers to do their bit to improve the way towns and cities are managed for pollinators. National pollinator strategies already exist for several countries, and local pollinator strategies and action plans are helping to bring together the key stakeholders in cities. Wider adoption of this type of united approach will help to improve towns and cities for both the people and pollinators that live there.

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This blog is written by Cabot Institute member Dr Katherine Baldock, NERC Knowledge Exchange Fellow, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Tag: butterflies

Urban gardens are crucial food sources for pollinators – here’s what to plant for every season