Want to help conserve plants in your garden? There’s an app for that.

Marius Munschek and colleagues have found that the public could help protect biodiversity in Germany through an approach called Conservation Gardening. Detailed in the journal Scientific Reports, their research outlines how Conservation Gardening – a method that combines everyday gardening with an ecological ethos, has the potential to combat the decline of native plants. Their study provides guidelines for implementing Conservation Gardening, incorporating details of suitable plant species and their cultivation requirements. Astoundingly, this research reveals that nearly 845 plant species categorised as threatened on the “Red List”, a catalogue of plants at risk of extinction, are fit for cultivation in backyards, with almost 66% being commercially available. This approach not only boosts biodiversity but also promotes sustainable gardening practices that are drought-resistant and low on fertiliser consumption, offering opportunities for climate adaptation in urban settings.

Conservation Gardening is the practice of planting declining native plants in urban green spaces. These spaces can provide the plants refuge and protection, and also aid in seed dispersal. Just like launching a space rocket, these gardens could become launchpads for seeds, helping them reach out to habitats beyond city limits. In addition to combating plant extinction and promoting plant diversity, Conservation Gardening also boosts insect biodiversity, particularly for insects that rely on declining plants and are themselves on the brink. However, putting Conservation Gardening into practice is not straightforward; it involves overcoming several challenges, including the continued preference for ornamental plants over native ones.

The impact of such an approach, the team predicts, could be unexpected. With the wide-scale adoption of conservation gardening across public and private spaces, it’s estimated that threats to plant species could decrease by up to 50% in certain regions and by about 25% across the entire nation. However, to fully leverage this potential and turn gardening into a mainstream conservation strategy, support from policymakers and the gardening industry, in terms of promoting and enhancing the availability of endangered native plant species, is imperative.

Yet, size does matter, and this is where the dilemma arises. Even though urban green spaces occupy a relatively small fraction of Germany’s total area, about 70% of the country’s population dwells in them. This provides a large volunteer-born labour force for conservation gardening, not to mention the opportunities it offers for secondary dispersal – spreading seeds outside their parent plant’s immediate vicinity – to natural ecosystems outside urban areas.

The researchers found that, on average, 41% of red-listed or at-risk species in German states are suitable for conservation gardening. Hamburg had the highest proportion of these species (53%), while Bavaria had the most significant raw count of red-listed species (1123 species). However, only 29% of these Bavarian species are capable of rebounding through conservation gardening. The silver lining is that there is still a large percentage of these at-risk-for-extinction species that can potentially be saved through this gardening method.

An exciting discovery by the researchers was that many species suitable for conservation gardening are already commercialised. About 650 species are available for purchase in Germany, with a singular producer, Strickler, supplying the majority. Still, there is an evident gap in supply, with 338 species remaining unsold, indicating a solid potential for commercial development of regional plant nurseries.

In the context of climate change and increasing droughts, conservation garden species appear to have a survival advantage. Around 45% of these species prefer dry soils, compared to 27% of conventional garden species. They also adapt well to different habitat conditions, such as wet areas, making them excellently flexible for grey water recycling practices. On top of this, they require fewer nutrients, with 25% favouring nutrient-poor soils versus 7% of traditional gardening species.

However, the researchers caution against viewing conservation gardening as a universal solution for biodiversity conservation. It is not a cure-all method, and other forms of nurturing flora, including non-native species, should not be overlooked. Munschek and colleagues write:

Our focus lies on declining native plants, but it’s important to note that CG should not be limited to those species alone, as it does not assign a higher moral value to natives over non-natives. In fact, supporting a mixture of species can be desirable due to their complementary functional traits. Non-native plants, for instance, can provide resources for insects when native plants have finished flowering. With the exception of gardens that plant invasives, most types of gardens already contribute to biodiversity, and CG should not be an exclusive approach to conservation.

Munschek et al. 2023.

To simplify the implementation of Conservation Gardening, the team has developed an R Shiny application, a digital tool that could act as a gateway to Conservation Gardening for amateur and professional gardeners alike, thereby helping more people get involved in this pragmatic form of conservation and contribute in their own way to the growing fight against the biodiversity crisis.

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Munschek, M., Witt, R., Kaltofen, K., Segar, J., Wirth, C., Weigelt, A., Engelmann, R.A. and Staude, I.R. (2023) “Putting conservation gardening into practice,” Scientific Reports, 13(1), pp. 1–11. Available at: https://doi.org/10.1038/s41598-023-39432-8.

Cover: Summer flowers in Germany. Image: Canva.