Des experts appellent à revoir la place des « mauvaises herbes » au jardin

On « Weed Day », marked annually on March 28, experts from German and Austrian institutions called for a fundamental rethink of how gardeners perceive and treat wild plants, arguing that common ornamental garden plants are ecologically worthless while so-called weeds are vital to the survival of insects, birds, and other wildlife. Bettina de la Chevallerie, managing director of the Deutsche Gartenbau-Gesellschaft 1822 (DGG 1822), told reporters that cultivated ornamental perennials and exotic shrubs frequently offer little or no food for native insects. She pointed to hydrangeas, forsythias, and cherry laurel as plants that may appear attractive but are, in her words, ecologically completely worthless because they provide little or no nectar or pollen. The mass planting of such species in private gardens creates what experts described as a hunger problem for insects. Margarita Hartlieb from the University of Vienna added that the derogatory label "weed" misleads gardeners into treating ecologically essential plants as dispensable nuisances.

Les orties et les pissenlits font vivre des espèces de papillons Wild plants including nettles, clover, dandelion, and mugwort, routinely pulled from gardens as unwanted growth, are in fact critical food and habitat sources for a wide range of species. Butterflies such as the peacock butterfly, small tortoiseshell, map butterfly, and red admiral lay their eggs exclusively on nettles, because their caterpillars feed solely on nettle leaves. Without nettles in gardens, these species cannot complete their life cycle. De la Chevallerie proposed replacing the word "weed" with "wildflowers" or "companion plants" to shift public perception toward the ecological role these plants play. „Dans tous les cas, le mot « weed » devrait être supprimé” — Bettina de la Chevallerie via Der Tagesspiegel The timing of garden maintenance also matters: removing and discarding faded plant stems in autumn destroys the pupae of butterflies attached to those stems, eliminating the next spring generation before it can hatch. Wild bees and other insects similarly rely on withered plant stems as overwintering sites, meaning autumn tidying can eliminate entire local populations.

Des pelouses entretenues décrites comme des écosystèmes « presque morts » Sophie Lokatis, a nature and species conservation expert at the Deutsche Wildtier Stiftung, described neatly trimmed lawns as environments that offer almost no ecological value. Many gardeners invest heavily in bird feeders and birdhouses during winter, but Lokatis argued that garden design is far more consequential for wildlife than supplementary feeding. „De telles zones sont presque mortes” — Sophie Lokatis via DIE WELT She noted that the number and diversity of songbirds have declined in parallel with the decline in insects over recent decades, with many bird species depending on insects as food, particularly when raising chicks. A further trend compounding the problem is the growing fashion for so-called grid-mesh fences with woven plastic slats, which Lokatis said offer neither nesting sites nor food in the form of berries or insects, while also releasing environmental toxins as the plastics degrade. Hedgehogs, increasingly rare in rural areas due to intensified agriculture, are now concentrated in gardens and urban green spaces, where they too depend on insects and shrubs for food and shelter.

Les experts demandent de laisser les tiges en place pendant l’hiver The experts' collective message on Weed Day centered on a shift away from the aesthetic ideal of the perfectly ordered garden toward designs that support biodiversity. Leaving wild plants to grow, allowing plant stems to remain standing through winter, and replacing ecologically barren ornamental shrubs with native species were all presented as practical steps available to individual gardeners. Weed Day provided a platform for conservationists and horticultural organizations to reach hobby gardeners who may be unaware that their planting choices affect local insect and bird populations. The framing of the debate around language — specifically the loaded term "weed" — reflected a broader argument that cultural attitudes toward tidiness and order in gardens carry measurable ecological consequences. Hartlieb's observation that the word "weed" implies dispensability was echoed by de la Chevallerie's call for a linguistic and conceptual shift in how gardeners relate to the plants growing uninvited in their plots.

Le déclin des populations d’insectes en Europe centrale est documenté depuis plusieurs décennies et est largement lié aux changements d’usage des terres, notamment à l’intensification agricole et à la diffusion de jardins privés simplifiés sur le plan écologique. La diversité des abeilles sauvages est une préoccupation particulière : selon la Deutsche Wildtier Stiftung, 604 espèces d’abeilles sauvages sont actuellement recensées en Allemagne. Une étude menée avec Sophie Lokatis, en collaboration avec la Freie Universität Berlin, a constaté jusqu’à quarante fois plus d’abeilles sauvages, de coléoptères et d’autres insectes ailés dans les zones comportant des graminées et des fleurs de prairie que dans des pelouses tondues ras.