Strategically planting diverse, unmowed groundcovers under trees—known as creating “soft landings”—is a paradigm shift in ecosystem gardening, supporting caterpillar survival and, by extension, the local food web and biodiversity in ways traditional landscaping cannot.
Moving Past Traditional Landscaping: The Critical Role of Under-Tree Habitats
For decades, homeowners and municipal landscapers have defaulted to the familiar: turf grass grown right up to tree trunks, mowed frequently for aesthetics and ease of maintenance. Yet this seemingly innocuous practice inadvertently creates what ecologists call an “ecological trap,” threatening the survival of lepidoptera (the insect order containing moths and butterflies) at a stage critical to their life cycle.
The science is clear: many species of caterpillars, after feeding on tree leaves, naturally drop to the ground to complete their pupation process. In a woodland, leaf litter and diverse undergrowth shelter them from predation and mechanical threats. In mown lawns, however, they are crushed, exposed, or left with nowhere to burrow.
Why ‘Soft Landings’ Are a Gamechanger
Soft landings—areas of deliberately planted, unmowed groundcover beneath trees—reset this equation. According to entomologist Doug Tallamy, native oak trees alone can support over 530 species of moths and butterflies, but only if adjacent ground habitat allows caterpillars to finish their development (AP News). Removing leaves and mowing these areas undermines the entire biological role trees play in the food web.
- Supports Full Life Cycle: Soft landings enable caterpillars to transition safely into moths or butterflies, maintaining pollinator populations and, by extension, the birds and small mammals they feed.
- Enhances Urban Ecosystems: Under-tree plantings can turn even small yards or park strips into critical habitat patches, stitching together fragmented green networks essential for ecosystem resilience.
- Biodiversity Refuges: These zones provide cover and resources for a host of beneficial insects—fireflies, native bees, lacewings, beetles—beyond just lepidoptera.
The Real Problem: Habitat, Not Just Food
Much attention has been given to planting nectar- and pollen-rich flowers for pollinators. However, as Tallamy and leading horticultural experts have pointed out, habitat is often the limiting factor—not food alone (National Wildlife Federation). Without suitable shelter, beneficial insects cannot complete their reproductive cycles, regardless of how many flowers bloom nearby.
This insight reframes property management and urban planning: a landscape rich in floral resources but poor in safe overwintering and pupation sites ultimately fails biodiversity.
Strategic Implementation: How to Create a Soft Landing
Experts recommend a two-stage approach:
- Stop Creating Barriers: Cease mowing and compacting soil beneath the canopy. Allow fallen leaves to accumulate naturally, providing both mulch and microhabitat.
- Plant for Function: Replace lawn with native groundcovers, sedges, ferns, and shade-tolerant perennials. These create complex vertical structure—crucial both for soil protection and for supporting a wider web of life.
Contrary to myth, even shade-loving bulbs and wildflowers can thrive if selected to match local conditions. Lists of recommended species often include:
- Maidenhair or Lady Fern (Adiantum, Athyrium)
- Wild Ginger (Asarum canadense)
- Woodland Phlox (Phlox divaricata)
- Sedges (Carex spp.)
- Wild Violets (Viola spp.)
- Blue-stemmed Goldenrod (Solidago caesia)
Protecting Tree Health During Conversion
It’s vital to avoid damaging sensitive tree roots when transitioning away from turf. The best-practice method is to smother grass with layers of newspaper and mulch, planting small plugs to minimize disturbance. Raised beds should be avoided around established trees, as roots need unimpaired access to oxygen and water (International Society of Arboriculture).
Ripple Effects: User, Developer, and Industry Implications
For homeowners: Adopting soft landings is not only ecologically responsible but often lower maintenance than recurring mowing, as leaves and plant debris are left in place as mulch. The result: healthier trees, fewer garden pests (as birds and predatory insects abound), and richer seasonal interest.
For landscape professionals: This shift demands knowledge of native plant communities, soil health management, and construction-free planting methods. There is growing demand for expertise in habitat-first, not just ornamental, landscaping.
For policymakers and developers: Urban design codes that prioritize tree “donuts” of mulch or sod undermine citywide biodiversity plans. Integrated biodiversity corridors, in which soft landings are standard, may become the new regulation and a differentiator for sustainable development projects. This approach, advocated by leading institutions like the National Wildlife Federation, is already showing measurable boosts in pollinator abundance and bird populations (NWF Report).
The Strategic Future: From Isolated Trees to Living Networks
The soft landing model reimagines every tree in the built environment as a potential biodiversity powerhouse—not just as a static landscape element but as a hub in a living network. As more municipalities, campuses, and homeowners adopt these techniques, fragmented “green deserts” of lawn can be rewoven into ecologically robust corridors. This systemic shift may be necessary to buffer our urban and suburban regions against pollinator loss and the ripple effects that follow throughout local food webs.
Key Takeaways & Action Items
- Replace under-tree lawn grass with diverse, native groundcovers and let leaves remain in place.
- Select plant species appropriate to your climate and tree’s shade tolerance, using tools such as the National Wildlife Federation’s Native Plant Finder.
- Avoid soil disturbance and raised beds—smother grass and plant plugs instead.
- Educate neighbors and clients: soft landings mean more butterflies, birds, and resilient landscapes.
By elevating the humble under-tree planting zone into a keystone of modern ecosystem gardening, we have the opportunity to change not just gardens, but the urban and suburban environment for generations to come.
