Embrace your bald patches!

Bald patches in beds and lawns good for garden wildlife

Gardeners should embrace the odd bald patch in their beds and lawns if they want to support certain wildlife, finds new research from the Royal Horticultural Society (RHS).

In the third paper from its four-year Plants for Bugs study, a team of researchers from RHS Garden Wisley looked at the particular needs of ground-dwelling invertebrates in gardens. They found that overall the denser the vegetation, the more ground-active invertebrates but that ground-dwelling spiders were found in greater numbers among sparser plantings.

Spiders are important predators and a valuable part of the natural balance in a garden, feeding on a variety of prey including biting midges and sap-sucking insects. Planting slightly smaller, younger plants and letting them fill out and embracing the occasional bald patch of earth is therefore not only economical, but provides a habitat different to that provided by full, mature borders.

RHS researchers also found that evergreen plants such as holly, Christmas box and pittosporum might have a special role to play for invertebrates. Evergreens, while not as popular as some showy plants - roses or peonies for example -  were found to provide all-important shelter in the winter months, supporting a wide range and abundance of invertebrates including ladybirds, springtails and ground beetles.

In all, the study found that the best way to support invertebrates in gardens and promote a healthy ecosystem, is to choose plantings biased towards British native plants and encourage dense vegetation, while leaving some patches of bare soil. Near-native - northern hemisphere - and exotic - southern hemisphere - plants also have a positive role to play in providing a habitat for invertebrates, offering good evergreen winter cover and supporting pollinators when in flower. Many gardens are already important habitats for invertebrates, but this research helps refine the advice given to gardeners wanting to maximise their garden’s potential and support declining invertebrates.   

To support invertebrates in gardens the RHS advises:

  • The perfect cover: Let planting fill out, but keep some areas sparser to help specific groups notably spiders. Although not covered in this research, some ground-nesting bees also make use of patches of bare ground.
  • More local: Plant densely with plenty of native and near-native plants to support the greatest number of ground-active invertebrates but be prepared for more nibbled plants than exotic plant schemes.
  • Winter protection: Whatever the plant origin, try to include some evergreens in your garden to give shelter to invertebrates.
  • Decide priorities: Choosing more exotics in your planting scheme might mean it supports marginally fewer plant-dwelling and ground-active herbivores, but will mean potentially fewer nibbled plants and should help extend the season for pollinators if you choose flowering exotics.
  • Be bio-diverse: For rich species diversity, follow all of the above. Don’t limit yourself to just a few different plants - this and other studies suggest the greater the variety of plants in a garden, the richer the diversity of invertebrates it will support.

Andrew Salisbury, principal entomologist at the RHS, said: “Ground-dwelling invertebrates such as predatory ground beetles and ground-active spiders are vital garden predators whilst springtails, woodlice and millipedes break down dead plant matter returning nutrients to the soil. The power of a garden lies in its very smallest inhabitants. Gardeners who look after them will have the greatest positive impact for biodiversity.”

The third and final paper ‘Enhancing gardens as habitats for soil-surface-active invertebrates: should we plant native or exotic species?’ was published in the journal Biodiversity and Conservation.

For more information about the RHS Plants for Bugs research project and advice on how you can support insects in your garden visit www.rhs.org.uk.