RHS’s Top 10 beneficial garden species

The Royal Horticultural Society (RHS) has complied a list of the top ten beneficial garden species.

The list, which compiles the top ten most-asked-about species for biodiversity, is designed to celebrate the wildlife of our gardens and highlight the benefits of encouraging more species into our outdoor spaces.  

The list was built from enquiries to the RHS Gardening Advice Service, which gets thousands of queries from gardeners every year. 

Lichens are at the top of the list. Lichens can often be found growing on trees or shrubs, providing food for other garden wildlife and creating new habitats by providing shelter for invertebrates and nesting materials for birds and mammals. Lichens are often associated with good air quality as they carry out photosynthesis to capture atmospheric carbon, and certain lichens also absorb atmospheric nitrogen, a common pollutant. They regulate water and humidity levels by soaking up moisture during wet weather and slowly releasing it as water vapour afterwards.  

The insects at the top of the list come as no surprise: the benefits of pollinators and ladybirds are familiar to many gardeners. Ladybirds primarily eat aphids – it is said that a single ladybird can eat 50 aphids a day, or around 5,000 in a lifetime.  

The rose chafer beetle (Cetonia aurata) also makes an appearance on the list. This bright metallic green beetle often appears from May and the larvae feed on dead, decaying matter, helping composting in the garden.  

Social wasps also make an appearance. These vital garden predators feed on everything from caterpillars to green fly. Adult hoverflies are often wasp mimics, having no sting they are vital pollinators. The larvae of many species are predators of blackfly and other aphids. 

The growing interest in fungi and their role in the ecosystem is demonstrated by the appearance of beneficial fungi in multiple slots in the top ten. RHS Garden Wisley celebrated UK Fungus Day in October 2022, with around 1,000 visitors joining in with activities such as fungi walks and talks and learning how to inoculate logs with mycelium. 

Sulfur tuft and inkcap mushrooms are often confused for honey fungus as they appear in groups in the autumn, but these beneficial species help recycle dead wood and support plant health. They release micronutrients and humic acid that enrich soils and helps retain moisture, and the presence of fungi in soil improves its structure. By adding woody mulch or retaining pruning cuttings from healthy trees gardeners can encourage beneficial fungi in their gardens. 

Slime moulds are single-celled organisms that fuse together to create a supergroup which moves as a unit in search of food. They eat bacteria which decompose plant material, contributing to the nutrient cycling in a garden as they in turn are eaten by invertebrates such as nematodes.  

 The top 10 beneficial garden species for 2022 are: 

1. Lichens  
2. Native ladybirds 
3. How to encourage pollinators  
4. Solitary bees (Aculeate hymenoptera) 
5. Sulphur tuft fungi (Hypholoma fasciculare) 
6. Slime moulds 
7. Rose chafer beetle (Cetonia aurata) 
8. Ink cap mushrooms (Coprinoids) 
9. Hoverflies 
10. Social wasps  

Liz Beal, RHS Plant Pathologist, said: “We have seen a huge increase in gardeners wanting to find out more about the organisms they can encourage into their garden to naturally ward off the species that can be more damaging to their plants. Many of the gardeners that get in touch are also very curious about the wildlife they find and what they do, rather than looking for ways to get rid of them. A healthy garden ecosystem is home to a wide variety of wildlife, and we hope this list will help celebrate some of the friendly garden species that have a whole host of benefits for our plots and the wider environment.” 

The RHS is committed to becoming biodiversity positive by 2025 as set out in the charity’s 2021 Sustainability Strategy. To aid this, the RHS is encouraging gardeners to focus on the benefits of having a biodiverse garden and the contribution each species makes to a healthy ecosystem and the ways increased biodiversity can prevent any one species becoming to prevalent and harming plants.  

For more information on wildlife gardening, visit: www.rhs.org.uk/wildlife 

RHS members get free access to the charity’s one-to-one Gardening Advice Service, available by phone or email. Find out more about becoming a member at: www.rhs.org.uk/join 

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Alex Bestwick

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Alex Bestwick is a Digital Content Editor with a degree in Publishing and Creative Writing from York St John. When he’s not at work, he is usually reading, watching horror movies, or exploring the countryside. [email protected]

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