Why a patch of nettles is worth the stings

Stinging nettles have a poor reputation. Most of us learned to avoid them as children, and they turn up uninvited in the corner of the garden where nothing else will grow. But if you want more butterflies in your garden, a stand of nettles is one of the most productive things you can grow — and it costs you nothing but a little space and a pair of gloves.

Stinging nettle (Urtica dioica) is a native plant that supports a huge range of British wildlife. It is a larval food plant for several of our most familiar and colourful butterflies, a source of seed for finches in autumn, and a hunting ground for ladybirds, hoverflies and spiders. Few plants earn their keep so generously. Leaving a patch to grow is one of the simplest wildlife gardening jobs you can do.

Which butterflies need stinging nettles

Four of our best-loved garden butterflies cannot breed without nettles. The females are fussy: they will only lay their eggs where there is a good supply of young, tender nettle leaves in warm sunshine.

• Peacock — the most spectacular of the group, with its bold eyespots. Females lay clusters of eggs on the undersides of nettle leaves in spring and summer, and the black, spiny caterpillars live together inside a silk web spun across the nettle tops.
• Small tortoiseshell — once extremely common, this butterfly has declined sharply in many areas. Its caterpillars feed in groups on nettles, and gardens with a decent nettle patch can be genuinely important for it.
• Comma — the caterpillar looks remarkably like a bird dropping, which is excellent camouflage. It tends to feed on nettles growing in sunny, sheltered spots, often on isolated plants rather than dense beds.
• Red admiral — increasingly breeding in Britain rather than arriving as a migrant, and nettles are its preferred food plant here.

Because these butterflies produce several broods between spring and early autumn, they need a steady supply of fresh nettle growth right through the season. That is where a little management comes in.

Where to put your nettle bed

Sunshine is the single most important factor. Nettles growing in deep shade are largely ignored by egg-laying females, so choose a spot that gets a good few hours of direct sun, ideally facing south or west. Shelter matters too — against a fence, wall or hedge is ideal, as butterflies will bask and feed nearby.

You do not need much room. A patch measuring roughly one metre by two metres will support a useful population of caterpillars and still leave the rest of the garden untouched. Tuck it behind a shed, along a boundary, or in the corner where the compost heap lives. Nettles thrive on rich, nitrogen-rich soil, so somewhere slightly scruffy suits them perfectly.

Keeping nettles in their place

Nettles spread enthusiastically by underground rhizomes, and a patch left alone will happily march across a border. The trick is to contain them without fighting them.

• Sink a rigid barrier — paving slabs on edge, or a length of stout plastic edging — around the patch, leaving about 30cm above ground.
• Alternatively, sink a large pot or old bucket with the base removed into the soil and grow the nettles in that.
• Plant in spring or autumn. Seed collected from a friend's patch in late summer germinates readily, and you can also lift a few rooted runners.
• Wear thick gloves and long sleeves when you work around them, and pull up any runners that escape beyond the boundary while they are still small.

Once established, a nettle patch largely looks after itself. It needs no feeding, no watering in all but the driest spells, and no weedkiller — which is just as well, since sprays would defeat the entire point.

A cutting routine that helps rather than harms

Left to its own devices, a nettle patch eventually becomes tall, woody and full of seed, which is far less useful to butterflies than fresh leafy growth. The answer is not to cut it all at once, but to cut it in sections.

In early June, cut back roughly half the patch to about 15cm from the ground. This stimulates soft new shoots, exactly what female peacocks and commas are looking for, and gives you a second flush for the summer broods. Leave the other half standing so that any caterpillars already feeding have somewhere to go. Three or four weeks later, cut the second half, by which time the first is regrowing nicely.

Never strim or mow the whole patch between April and September, as you will destroy eggs, caterpillars and pupae in one sweep. From late September, leave the stems standing. The dead, hollow stalks make excellent overwintering sites for insects, and the seed heads that follow are a favourite autumn food of goldfinches.

More than a caterpillar food plant

Butterflies are only part of the story. In summer, nettle stems are often smothered in aphids, which in turn draw in ladybirds, hoverflies and lacewings, and provide a rich larder for blue tits feeding their young. Several species of solitary bee and overwintering ladybird shelter inside the hollow stems of old nettles. Wrens, dunnocks and blackbirds rummage through the base of a patch for insects and seed.

You can even make use of the plants you cut. Steep the leaves in a bucket of water for a fortnight, then dilute the resulting liquid to make a free, nitrogen-rich feed for your tomatoes and leafy crops. It smells dreadful, but it works.

So before you reach for the strimmer, consider leaving that awkward corner alone. A modest patch of nettles, sited in sunshine and cut in stages, will reward you with peacocks, commas, tortoiseshells and red admirals drifting through the garden — and a great deal more besides.