What rubber lawn edging is meant to do

Rubber lawn edging is a flexible strip that sits between a lawn and a planting bed, creating a clean separation that keeps grass from creeping into flower borders and helps mulch stay in place. The Royal Horticultural Society (RHS) explains that a well-defined lawn edge with a decent drop down to the border will help keep mulching material where it belongs. The University of Illinois Extension notes that edging forms a neat line between planting areas and turf, and when installed properly it should blend in, minimize hand trimming, and contain mulches within the bed.

Before you buy: Recycled-tire rubber edging is convenient and long-lasting, but research on rubber mulch raises questions about zinc, leachates, and fire risk that are worth weighing before you install it near food plants or water.

Why gardeners choose rubber edging

According to the Illinois Extension’s discussion of rubber mulch, convenience is rubber’s primary benefit in the landscape. Rubber mulch decomposes much more slowly than wood-based mulches, so reapplication is infrequent.

The RHS advises that broad, sweeping curves on lawn edges are easier to maintain than intricate curves or complex shapes, so plan the line before choosing any strip material. However, the Illinois Extension’s bed edges post, written by horticulture educator Rhonda Ferree, does not list rubber among the common edging materials it reviews. It covers metal, plastic, wood, brick, stone and concrete, and notes that the material should be long-lasting, strong, and complement the landscape. If you are considering rubber, weigh its appearance and durability against those materials; our guides to metal edging, plastic edging and lawn edging materials compare them.

What research on recycled-tire rubber mulch tells us

Most of the available research on recycled-tire rubber in landscapes comes from studies of rubber mulch, not edging strips. The findings are not a direct measure of what an edging product will do, but they highlight characteristics of tire rubber that may be relevant when you decide where and how to use rubber edging. The Washington State University (WSU) publication by Dr. Linda Chalker-Scott and the Illinois Extension’s 2019 blog post by Chris Enroth both summarize this research.

Weed control and plant health

The WSU paper states that rubber tire mulch was less effective in controlling weeds in herbaceous perennial plots than wood chips, and sawdust performed better for Christmas tree production in terms of weed control, microbial biomass, and soil chemistry. The Illinois Extension post adds that studies identified symptoms of leaf yellowing, reduced tree growth, and increased tree mortality where rubber mulch was used. Soil checks showed high levels of zinc, which can be toxic to plants and could cause leaf chlorosis.

Zinc and other metals

According to WSU, rubber contains very high levels of zinc, as much as 2 percent of the tire mass. A number of plant species have been shown to accumulate abnormally high levels of zinc, sometimes to the point of death. The same source notes that a USDA researcher who studied zinc and other metals for decades strongly believes ground rubber should not be used in any composting, potting medium, or casually dispersed on agricultural or garden soils because of zinc toxicity. Acidic soils and aquatic systems are particularly sensitive, since heavy metals are less tightly bound to the soil and more available to plant and animal uptake.

Leachate and aquatic life

WSU reports that research at Bucknell University indicates rubber leachate from car tires can kill entire aquatic communities of algae, zooplankton, snails, and fish. At lower concentrations, the leachates cause reproductive problems and precancerous lesions. The greatest threat of contamination appears to be to freshwater habitats. The Illinois Extension post echoes this, noting that rubber mulch decomposition releases breakdown products such as heavy metals, plasticizers, and accelerators into the environment.

Flammability and decomposition

WSU states that compared to a dozen other mulch types, ground rubber is more likely to ignite and more difficult to extinguish. In areas where the possibility of natural or man-made fires is significant, rubber mulches should not be used. The Illinois Extension post confirms that when ignited, rubber mulch is most difficult to extinguish. Both sources also emphasize that rubber is not permanent. WSU explains that many bacterial species can use rubber as their sole energy source, and white-rot and brown-rot fungal species can detoxify some of the additives used in tire manufacture. The Illinois Extension post adds that certain bacteria feed readily on rubber material, and over time the painted coating fades, leaving behind identifiable shreds of used tires.

Practical points to weigh before installing rubber edging

Because the research on rubber mulch raises concerns about zinc and leachates, you may want to keep recycled-tire rubber edging away from vegetable gardens, fruit plantings, and any area where soil health directly affects food you eat. The WSU paper advises that rubber should not be used as a landscape amendment or mulch, and that toxic substances leach from rubber as it degrades, contaminating soil, plants, and associated aquatic systems. While an edging strip is a smaller, more contained product than a mulch layer, the same materials are involved.

If your property includes a pond, stream, or drainage swale, consider placing rubber edging well away from the water’s edge. WSU notes that freshwater habitats are the most sensitive to tire leachates. In fire-prone areas, WSU says rubber mulches should not be used, which is a reason to consider a different edging material there. The Illinois Extension bed edges post points out that steel edging is the longest lasting and works well where a great deal of side-strength is required, while brick and stone make useful and decorative edging when set on a proper base.

Installation basics and safety

No matter which edging material you pick (see how to install lawn edging), the RHS recommends starting by deciding on a shape, marking it with a string line for straight edges or a garden hose for curves, and then cutting along the line with a half-moon edger or flat-backed spade. For a flat-backed spade, the RHS suggests marking a depth of 7.5 cm (3 in) on the blade and inserting it to that depth. After cutting, remove the unwanted grass and check that the line is neat and even from both ends.

When installing rubber edging strips, always follow the manufacturer’s instructions for anchoring and joining pieces. The Illinois Extension bed edges post explains that most frost heaving can be stopped by using grooved or lip-style edging, steel anchoring stakes, and proper installation procedures. That advice was written for plastic and metal edging, so for rubber strips follow the maker’s instructions.

Any project that involves digging a trench for edging requires a call to 811. The national before-you-dig service states that you should contact 811 or use your state 811 center’s website a few business days before you begin any digging, including common projects like installing fences or planting trees and shrubs. After you contact 811, wait for utilities to mark the approximate location of buried lines, then dig carefully around any marks and consider relocating projects that are close to buried utilities. Even shallow digging can hit a utility line, so this step is essential.

Frequently asked questions

Is rubber lawn edging safe for vegetable gardens?

Research on recycled-tire rubber mulch, summarized by Washington State University and the Illinois Extension, shows that rubber can leach zinc and other compounds that may harm plants and aquatic life. While edging strips are not the same as mulch, the same materials are involved, so keeping rubber edging away from food-growing areas is a cautious approach.

Does rubber edging really last forever?

No. Both WSU and the Illinois Extension explain that rubber is broken down by bacteria and fungi. Over time, the material degrades, the color fades, and the product may release breakdown substances into the soil.

Can I install rubber edging without digging?

Follow the edging maker’s instructions. The RHS describes cutting a lawn edge with a spade or half-moon edger to create a clean border, and the Illinois Extension notes that grooved or lip-style edging, steel anchoring stakes and proper installation stop most frost heaving in plastic and metal edging. If any trench is involved, contact 811 first. Check the product instructions for the exact method.

For more on rubber lawn edging options, visit our rubber lawn edging category.

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