Why reeds and rushes earn their place

Few things lift a garden pond quite like a stand of rushes catching the light, or the rustle of reed stems in a September breeze. Beyond looks, they are quietly doing serious work. Upright stems give dragonflies and damselflies somewhere to climb when they emerge from the water, they break up the wind for amphibians, and they offer shelter for everything from water boatmen to young frogs hiding from herons.

They also help the pond look established rather than newly filled, softening the hard edge between water and bank. The catch is that many of them are vigorous growers. Plant the wrong one in the wrong place and within three seasons you have a reed bed rather than a pond. The trick is choosing carefully and planting with containment in mind from day one.

Know what you are actually planting

The names get muddled in garden centres, and the muddle matters because the plants behave very differently. True reeds, true rushes and the plants we loosely call rushes are not the same thing.

• Common reed (Phragmites australis) is magnificent in a large wildlife pond or a dedicated reed bed, running underground and forming dense colonies. In a small garden pond it will take over. Give it a permanently contained bed or admire it elsewhere.
• True rushes (Juncus species) are the safest bet for most gardens. Soft rush makes a tight clump of tall, fine stems. Sword-leaved rush is smaller and tidier again, ideal for a modest plunge pool or half barrel.
• Bulrushes are reedmaces (Typha). The dwarf reedmace is well behaved enough for a small pond, but the greater reedmace is a thug with a running rhizome.
• Flowering rush and sweet flag are lovely but not true rushes, and both spread steadily. Use them where they have room.
• Sedges (Carex) are the quiet workhorses, clump-forming and content in shallow margins.

If you have a small pond, stick to clump-formers. If you have space and can contain the runners, the bolder native species become a genuine habitat feature.

Plant in baskets, always

Loose planting into a silt-bottomed pond is asking for trouble. You cannot lift, divide or thin out anything without wading in, and runners will roam wherever they like. Aquatic baskets solve nearly all of this.

• Use a mesh basket roughly twice the diameter of the root ball. A cosy basket keeps growth in check; a huge one gives it licence.
• Line the basket with hessian or a fine basket liner, then fill with a loam-based aquatic compost. Ordinary potting compost is too rich, too light and will cloud the water.
• Set the plant so the crown sits just above the compost surface, then top off with a 2cm layer of washed gravel to stop fish and birds stirring everything up.
• Plant between April and June, when the water has warmed but before the growing season is in full swing.

Position the basket on a marginal shelf so the crown sits at or just below the water surface. Most rushes and sedges are happiest with 0–15cm of water over the compost; reeds will tolerate deeper water once established, but starting them shallow helps them settle.

Keeping them in bounds

Containment is a regime, not a one-off job. Check baskets each spring for roots pushing through the mesh, and re-pot into the same size basket rather than a bigger one. Dividing every two to three years keeps plants vigorous and stops them flowering themselves into a takeover.

Watch for self-seeding too. Soft rush in particular scatters seed freely, and you will find seedlings in neighbouring baskets and along the damp edges of the pond. Pull them while they are small, when the roots come away easily.

Never introduce invasive non-native aquatics alongside your rushes. Floating pennywort, water fern, parrot's feather and New Zealand pigmyweed will smother a pond far faster than any reed, and several are subject to legal controls on sale and disposal.

Looking after the stand through the year

Leave the stems standing through autumn and winter. Hollow reed and rush stems are exactly the sort of sheltered nook that overwintering insects and amphibians need, and the seed heads feed birds. Tidying them in October removes a whole season of wildlife value for the sake of neatness.

Cut back in late February or early March, just as new shoots begin to push through. Cut to about 10cm above the basket and leave the stems in a loose bundle on the pond edge for a few days, so any invertebrates hiding inside can crawl back to the water. Once they have, compost the stems or add them to a wildlife heap.

Feed sparingly, if at all. Rich water encourages algae and floppy growth; the plants will take what they need from the pond itself. Top up the gravel mulch after dividing, and check the water level in dry spells, since baskets on a shallow shelf can dry out quickly in a hot July.

What you get back

A well-managed fringe of rushes turns a pond from a puddle into a habitat. Damselfly larvae crawl up the stems to emerge, frogs use the clumps as cover when moving between water and border, and the stems give tadpoles and small fish somewhere to hide. On a still evening the verticals catch the low sun and the whole pond looks twice the size it is.

Start with two or three modest clumps in baskets, keep them divided, and let the planting mature slowly. Restraint now means you will still be enjoying the reeds in ten years rather than fighting them.