You already know what volcanic lapilli are used for as a material: they drain, they don’t break down, they protect the surface. Here we answer the next question — the one you ask when you’re looking at your own garden: how do you actually use lapilli in a flower bed, along a path or around your plants, and how do you keep it looking good over the years?
Why use volcanic lapilli in flower beds?
A bed mulched with lapilli does most of the work on its own. The mineral layer blocks light from reaching weed seeds, slows water evaporation and buffers temperature swings around shallow roots. And unlike bark or other organic mulches, lapilli don’t decompose: no seasonal topping up, no insects drawn to decaying organic matter, and the dark reddish-brown colour holds up through years of rain and sun.
Then there’s the look, which matters in a bed as much as the function: the warm mineral tone contrasts with the green of the plants and gives the whole area a tidy, finished appearance — the signature of Mediterranean-style, low-maintenance gardens.
How do you lay lapilli in a flower bed?
Laying is simple, but a few details separate a result that lasts for years from one you’ll redo:
- Prepare the ground — remove existing weeds with their roots: mulch blocks new weeds, it doesn’t kill established ones.
- Consider a breathable membrane — under the lapilli, a permeable landscape fabric lets water and air through while making it even harder for weeds to push up. In densely planted beds you can skip it.
- Spread an even layer — the cover should be continuous and thick enough to keep light off the soil; too thin lets weeds through, too thick just wastes material.
- Take care of the edges — an edging strip (steel, stone or terracotta) keeps the lapilli in place and separates the bed from the lawn, so the granules don’t migrate where you don’t want them.
Do lapilli work for paths and walkways?
Yes — it’s one of their most appreciated uses. Being rock, lapilli take foot traffic without crumbling and drain rainwater away, so the path never turns muddy. For walkways the coarser grade is the usual choice, more stable underfoot, held in place by lateral edging. The result is a permeable, very low-maintenance path: no puddles, no grass to cut, just an occasional rake to level the surface.
Which plants pair well with lapilli?
Lapilli are an inert material with a reaction close to neutral, so they get along with most garden plants. The most natural pairing is with Mediterranean and aromatic species — lavender, rosemary, sage, thyme — which like dry, well-drained surfaces. They work just as well with succulents in open ground or pots, with ornamental grasses, and with olive trees and citrus in the garden or in large containers on a balcony.
Around acid-loving plants such as hydrangeas, azaleas and camellias you can use lapilli as a decorative cover: being inert, they don’t meaningfully shift the soil reaction, which for these plants is managed through the right substrate and feeding.
Lapilli or expanded clay in the garden?
It depends on the job. Lapilli are heavier and more stable: they stay put in beds and paths even in wind and rain, which makes them the better choice for outdoor surfaces. Expanded clay is lighter and more regular, and performs best in pots — as a drainage layer at the bottom or a surface cover — where weight matters. In many gardens the two coexist: lapilli outside, expanded clay in the containers.
How much maintenance does a lapilli-mulched garden need?
Very little — that’s the point. Once or twice a year it’s worth raking the surface to redistribute the granules and remove leaves and organic debris which, decomposing on top of the mulch, would give weeds a foothold. If the layer thins out in high-traffic spots over time, you top up only where needed. Nothing gets replaced: the material you laid stays there, season after season.
Volcanic lapilli in the Arber range
In the Arber range you’ll find selected volcanic lapilli in two grain sizes — the finer one for decorative covers and pots, the coarser one for drainage, paths and beds — for people who care for their garden with an expert’s eye. Formats and usage guidance are on the label and the product sheet.
Always check the label and the technical sheet for grain size and specific usage guidance.
Planning a bed or a path and not sure where to start? Browse the volcanic lapilli in the catalogue and the gardening section, or contact us: we’ll help you choose the right material and grain size.
Frequently asked questions
Do you need a membrane under lapilli?
It’s not mandatory, but it helps. A breathable landscape fabric makes it harder for weeds to push through and stops the lapilli mixing into the soil over the years. In densely planted beds, where the ground is almost fully covered, you can do without it.
Do lapilli change the soil pH?
Not appreciably: they are an inert material with a reaction close to neutral, they don’t decompose and don’t release substances that meaningfully shift the soil reaction. That’s why they can be used as a cover even near acid-loving plants.
Lapilli or bark for mulching beds?
Bark adds organic matter but decomposes and needs redoing periodically. Lapilli don’t feed the soil but last practically forever, don’t attract insects and keep a tidy look far longer. If you want low maintenance and a mineral look, lapilli are the more practical choice.
Can lapilli be used in pots on a balcony?
Yes: as a drainage layer at the bottom of the pot or as a decorative surface cover that limits evaporation. In very large containers keep the weight in mind: if you need something lighter, expanded clay is the alternative.