We have come to realise over the last couple of decades what rich habitats our gardens are for wildlife. Yet gardens are very different to the British countryside, on average containing 70% non-native plants, but having much greater plant diversity. Because there was no consensus of opinion on whether planting UK natives in our gardens was better for wildlife than non-native plants, which originate elsewhere in the world, the Royal Horticultural Society began a rigorous scientific study in 2010 to find out, Plants for Bugs’.
36 3m x 3m plots were created at RHS Wisley and another site in Surrey and each plot was planted with a mix of 14 plant species native to one of 3 geographical zones: the UK (native), the northern hemisphere excluding UK (near-native) and the southern hemisphere (exotic). Each bed contained bulbs, perennials, shrubs, a climber, grasses and ferns. Sampling of invertebrates were recorded over four consecutive years. Tens of thousands of insects were recorded including eight species of bumble bees, more than 50 species of spider and 40 of ground beetle. In 2011, for example, more than 2,600 species of pollinating insects were recorded.
So what conclusions did they draw from all the data? A paper was recently published on pollinating insects recorded and the main finding relevant to gardeners and anyone who designs public or private green spaces was that there was no difference between the number of pollinating insects that visit native and non-native plants. Non-native plants can be just as valuable to pollinating insects as natives. It was found that the diversity of species is far more important than whether they are native or not.
Here are the 3 key things the RHS say we as gardeners and garden designers can do to help increase levels of pollinators in our gardens.
Plant a mix of flowering plants from different countries and regions of the world. Place the emphasis on plants from the northern hemisphere including UK natives such as Veronica spicata ‘Royal Candles’-cultivar of Spiked Speedwell, or Lonicera periclymenum ‘Graham Thomas’-cultivar of Common Honeysuckle, with near- natives like Scabiosa caucasica- the Caucasian Scabious and Eupatorium maculatum ‘Atropupureum’ – Jo Pye weed. Then include ‘exotics’ from the southern hemisphere for late nectar such as Lobelia tupa, Fucshia and Osteospermum. Take a look at this list for more ideas.
Plant for a long season. It is not only us that enjoy a long season of flower in our gardens. Pollinators need to find nectar right through the year, so including early flowering plants such as Hellebores, Crocus, Winter flowering Clematis, Snowdrop and Mahonia is important. Later flowering plants such as Asters, Dahlias, Anemone x hybrida and Aconitum carmichaelii and grasses such as are also useful to provide late nectar sources. Here is a list giving a guide to seasonal flowering plants for pollinators.
Pack as many species of plant in as you can manage. Not surprisingly, the more species you fit in the more bees, hoverflies and other pollinating insects will be supported by your garden. And don’t despair if you only have a window box, pick the right plants and you will still be helping the pollinators in even the smallest space. Layer plants starting with bulbs and perennials and working up to shrubs and trees. Try squeezing slender plants like Verbena bonariensis, Foxgloves or Linaria purpurea between other plants. Don’t forget climbers which will only take up vertical space if trained well. A sunny spot will be the greatest draw for insects but even in shade Sarcococca, Hydrangea and Bergenia, for example, will flower well. Trees can also be good providers of pollen and nectar. Willow, Birch, Maple and Lime are ideal for this in larger spaces.
And finally, take a note of which plants attract the most insects in your area and add more of those which are buzzing with insects! Oh and don’t forget your allotment, orchard or veggie patch. Let a few veg plants flower and plant an edging of annuals such as cornflower, larkspur or marigolds for cutting. I am going to plant a strip of wild flowers to edge my new veggie garden and draw in insects to pollinate my crops. If you have space for a few fruit trees then let the grass grow longer beneath them and add wild flower plugs and spring bulbs. The extra insect life attracted will help to pollinate my apples, pears and plums hopefully.