Why sedges earn their place in gravel

A gravel garden asks a lot of its plants. Sun bakes the ground, rain drains through in minutes, and the soil beneath is usually thin, stony and poor. That suits a select group of plants very well, and sedges — the genus Carex — are among the most useful and least demanding of them. They are not grasses, though they share the same linear, arching foliage; they belong to the Cyperaceae family, with triangular stems and nut-like seeds. In gravel they knit low mounds of colour and texture between silver-leaved shrubs and drought-loving perennials, and they hold the shape of a planting through winter when so much else has collapsed. They ask for almost nothing in return: no feeding, no staking, and no watering once established.

Getting the ground right before you plant

Start with the sunniest spot you have. Drought-tolerant sedges want at least six hours of direct light, and the bronze and olive-leaved sorts want more than that. Drainage matters far more than soil quality. On heavy clay, fork the subsoil to 30cm, then work in a 10cm layer of horticultural grit so water can move away rather than sit. Plant each crown into a mix of garden soil, sieved compost and grit in roughly equal parts, sitting it slightly proud of the surrounding ground.

Then mulch the whole bed with 5–8cm of 10mm gravel, keeping it clear of the crown of every plant. That gravel collar does real work: it stops damp collecting around the crown in winter, suppresses weeds, and bounces light back up into the foliage. Water new plants through their first summer only. After that, leave them to the rainfall.

The best drought-tolerant sedges to grow

• Carex oshimensis 'Evergold' — the workhorse of the group. Cream and green variegated, about 30cm, evergreen, happy in sun or light shade, and superb against dark gravel.
• Carex oshimensis 'Everlime' — similar habit with lime-green edges, a touch brighter in shade.
• Carex testacea — olive-green shifting to orange-brown over winter. Give it the sharpest drainage you can and a warm, sheltered spot.
• Carex buchananii — stiff bronze-brown foliage to 60cm, evergreen and upright. Comb out dead leaves each spring.
• Carex comans 'Frosted Curls' — pale, curling and almost silvery, lovely as a gravel carpet, though inclined to sulk in cold, wet winters.
• Carex flagellifera — bronze and flowing, quick to settle, with seedheads that follow the stems down to the ground.
• Carex morrowii 'Variegata' — the one to use where a little shade creeps in at the edge of the gravel.

British natives for dry ground

Several of our own sedges are made for this treatment and bring a quieter, more local character to the planting. They are worth seeking out from native plant specialists.

• Carex flacca, glaucous sedge — blue-green and gently spreading, thriving on chalk and lime.
• Carex humilis — dwarf and tufted at 10–15cm, with softly downy leaves.
• Carex caryophyllea — spring sedge, short and neat, flowering early.
• Carex ornithopoda — bird's-foot sedge, a lime lover with a tidy, compact habit.
• Carex divulsa — grey sedge, one of the few that copes with dry shade.

Mix them with wild thyme, salad burnet and small scabious for a planting that looks as though it has always been there.

Where wetland sedges fit in

Not every sedge wants gravel. Our wetland species — pendulous sedge, greater pond sedge, hop sedge, common sedge — want the opposite: moisture-retentive ground that never quite dries out. That is not a reason to leave them out; it is a reason to shape the garden so both conditions exist side by side. A shallow, lined hollow at the low end of the gravel bed, fed by runoff, makes a natural rain garden.

Plant it with Carex elata 'Aurea', Bowles' golden sedge, for a shock of yellow-green, plus Carex nigra and Carex flava for texture and colour. Keep them contained in a buried liner or a distinct zone so they cannot creep into the dry bed, and be wary of greater pond sedge in a small garden — it runs hard. Pendulous sedge is handsome but self-seeds freely, so cut the flower spikes before they shed.

Looking after the planting

There is very little to do, which is part of the pleasure. In late winter, comb out dead foliage with a hand fork or gloved fingers, pulling gently from the base. Cut evergreen sedges back to 5–8cm every two or three years in late March, never in autumn, and cut deciduous types to the ground at the same time. Divide clumps every three or four years in spring, replanting the vigorous outer pieces and discarding the woody centre.

Do not feed them. Rich soil produces floppy, short-lived plants that lose the tight, architectural quality you planted them for. Leave the seedheads standing for the birds and for winter structure, and resist cutting into old, leafless wood on the bronze sedges — they will not reshoot from it. Get those few things right and your gravel garden will look settled, generous and entirely at home in the driest corner of the plot.