Study finds top 5 ways to provide for pollinators in urban gardens
Our gardens are a key habitat and food source for pollinators. No matter how small your space, you can support the survival of these invaluable insects
An insightful collaborative study between the Universities of Bristol, Northumbria and Cardiff and the RHS has uncovered patterns of nectar supply in urbans gardens, showing up huge differences in the quantity provided by different gardens and revealing how provision changes over the course of the year.
Nectar is the main energy source for adult pollinators, and is particularly important for powering flight muscles. This makes it a good currency for measuring and comparing the resource value of different plants and habitats.
How residential gardens are managed, and what plants are used, can make or break their value to pollinators. But the good news is, it's easy for us to help them - and it doesn't even matter how big a space you have. Just by introducing a couple of the plants recommended below, you're making a valuable contribution.
© Olivia Drake![]()
Why are urban gardens so important?
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They provide an estimated 85% of the nectar available in urban areas
Cities are expanding all across the world. Collectively, residential gardens cover 16-36% of urban land area worldwide. These gardens offer a unique opportunity for pollinator conservation, in which the combined action of many people can have a major impact on nectar resources at a landscape scale.
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They can support a high diversity of pollinators
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They provide a more consistent source of nectar than a rural landscape
Seasonal timing of nectar resources has a big impact on the success of pollinating insects. In rural farmland, nectar availability fluctuates massively over time, with supply over 10 times greater at some times than at others.
Because urban gardens exist at such a high density, are independently managed, and each have a fairly distinct and wide variety of plants, this smooths out large fluctuations in supply. Variation in nectar supply over time tends to average out across many gardens, resulting in an overall supply that is more stable and continuous through the year.
The study
In 2019, surveys were carried out in 59 residential gardens in the city of Bristol once a month from March to October; a timeframe that covers the vast majority of the UK pollinator flight season. The gardens encompassed a wide range of sizes and planting styles.
In each survey, the abundance and identity of open flowers were recorded, and combined with nectar production data for each species, to work out how much nectar was being produced by each garden each month. This would reveal the magnitude, fluctuation over time, and diversity and composition (in terms of contributing species) of the gardens' nectar supplies.
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- There is huge variation in the quantity of nectar produced by different gardens
- Nectar provision was not significantly affected by garden size
- Different gardens contained distinct sets of plants, giving a high overall plant richness
- Nectar supply peaks in July
- Different patterns in different gardens reduces peaks and troughs in supply
- Gardens with more diverse floras provide a more stable nectar supply
- Compatibility between plant and pollinator is a potential issue
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1. It doesn’t matter how big (or small!) your outdoor space is
How you manage your garden is much more important than how big it is when it comes to how much nectar is available. Even just a few key plants in pots can become a valuable resource when combined with whatever else is available around you. So don't worry about the size of your plot - simply make the most of what you have.2. Try to include a wide variety of plants with a range of flowering times
Including many different flowering plant species in your garden maximises both the consistency with which nectar is provided over time, and the diversity of pollinators that can access some of that nectar.By choosing plants that flower consecutively throughout the active pollinator season (March to October), you can provide a more stable supply of nectar. You could even coordinate with neighbours to grow plants that peak at different times!
3. Plant nectar-rich shrubs
The study found that often, a single shrub or tree provides the majority of a garden’s nectar in a given month. The three-dimensionality of shrubs, trees and climbers means that a large number of flowers are packed into a relatively small land area. Consequently, these were responsible for two-thirds of total nectar provision in the gardens studied.
If you have space, consider planting a nectar-rich shrub or climber such as willow (Salix), Pieris, Californian lilac (Ceanothus), currants (Ribes), apple or crabapple (Malus), firethorn (Pyracantha coccinea) or common honeysuckle (Lonicera periclymenum).
4. Prioritise flowers with an open shape, especially those blooming in summer and autumn
Open flowers are accessible to the widest range of pollinators, so prioritising these caters for the largest audience. Tubular flowers are often accessible only to specialist pollinators and can’t be accessed, for example, by short-tongued solitary bees and pollinating flies.Late summer and autumn is often a time when nectar provision drops, so choosing plants that flower during this window provides a valuable continuation of food.
5. Familiarise yourself with which plants are the most nectar-rich
All the good intentions in the world can be there, but the secret ingredient is to know which plants will provide the most nectar for pollinators. To ensure a plentiful supply in each season, try to include at least one from each section below in your garden.
Based on the study, the following plants are recommended for UK gardens to provide an abundance of nectar throughout the year.
This study formed part of the PhD research of ecologist Nick Tew, who went on to work with the RHS. You may also be interested in Nick's top 10 plants for specialist bees.
