The Royal Horticultural Society (RHS) has been running a “Plants for bugs” experiment at RHS Wisley since 2010 to find out which plants and combinations of plants are best for encouraging wildlife, specifically invertebrates (including pollinators) in our gardens. They planted up 36 3m x 3m sites with different combinations of native, near native and exotic plants and monitored the wildlife in each plot. At this time of year (Spring) when we are thinking about weeding, soil and which new plants we might like in our gardens (see the images to the right for some native plants that will do well in the typically alkaline, clay soils found around Faversham), the results of the RHS experiment are particularly interesting.
All gardens need pollinating insects, especially if you have fruit trees and bushes or peas, beans and squashes. Pollinators also help if you have annual and perennial flowers which you would like to self seed around your garden like Pot Marigolds , Toadflax and Aquilegia.
The RHS experiment found that the best way to get the maximum number of pollinators (like bees and hoverflies) in your garden is to use a mixture of native plants (don’t forget that includes plenty of lovely flowers like Roses, Cherry trees, Ox eye Daisies well as “weeds” – it’s good for every garden to have a weedy corner) and exotics to extend the season (everyone knows Buddleia as the “Butterfly bush” and they aren’t anywhere near a native British plant).
Bugs that live in your plants.
Lots of gardeners don’t like finding signs that leaves have been nibbled by aphids, thrips or earwigs. They are an important part of the food chain in your garden, they get eaten by predator invertebrates like Ladybirds and other beetles which, in turn, are eaten by the birds we all like to see in our gardens.
Other invertebrates that live in plants are the various species of detritivores; bugs that eat dead leaves, rotting wood and fungal and algal growths. These are good for the garden because they speed up the process of decomposition, tidying up the garden and improving the soil.
The RHS experiment showed that the more densely you plant your garden, the larger the population of plant dwelling invertebrates it supports. Although native and near native plants support the greatest numbers of these bugs, they will live in the exotic plants (plants from the southern hemisphere) too. Even if your garden is planted up with nothing but exotic plants it will support a bug population only 20% less than a garden with nothing but native plants.
Bugs that live on the ground.
As I try to explain on the Physic Garden You Tube channel, the RHS experiment found that a mixture of native plants, evergreen plants (including exotics) and some open spaces provide the best habitat for ground living invertebrates. Bugs such as Millipedes and Woodlice are types of detritivore (see above) which recycle rubbish; they like to live under plants but they don’t care where the plants come from.
Other ground living bugs are plant eating herbivores and they prefer native plants but the experiment found that they like evergreen non native / exotic plants which they can live under in Winter (two examples of such plants in the Physic Garden are Day Lilies and some of the evergreen ornamental grasses in the raised beds).
Finally, predatory invertebrates like Wolf spiders and centipedes like some patches of open ground on which they can stalk their prey.
It all sounds very confusing but it isn’t really. If you want to attract wildlife (invertebrates as well as the mammals, birds and amphibians that prey on them) it’s worth thinking about your planting. A good mix of native or near native plants (including weeds), plant them densely, add exotics to lengthen the season and leave a few open spaces. Last but not least, a few pieces of rotting timber here and there and a pond (even a tiny one) would send your wildlife approval rating through the roof!
For more information visit rhs.org.uk/plants4bugs and rhs.org.uk/plantsforpollinators