What is stinging nettle?

Stinging nettle identification is something most people learn the hard way. It’s a perennial that spreads by underground rhizomes and forms dense, upright patches in rich, moist soil. North America has a native form of it, and a European form has been introduced as well, so in Pennsylvania you’re likely seeing one or both.

The plant is covered in tiny hollow hairs that work like needles. When you brush against them, the tips break off and inject irritating chemicals into your skin. The burning usually fades within a few hours, though the itch can linger longer.

It isn’t a dangerous plant for most people, and it has real value. Butterflies such as the red admiral lay eggs on it, and foragers prize the young spring leaves. The trouble starts when a patch spreads into a path, a play area or the edge of the lawn where people walk in shorts.

Stinging nettle identification: what to look for

Learn to spot it from a step away so you don’t have to touch it.

• Stems: upright, 2 to 6 feet tall, usually unbranched, four-angled and covered in bristly hairs.
• Leaves: in opposite pairs, lance- to heart-shaped, with coarse saw-toothed edges, deep veins and a pointed tip.
• Flowers: tiny and greenish, in thin branched strings that hang from where the leaves meet the stem, from early summer on.
• Growth habit: a solid stand of many stems spreading from yellowish underground rhizomes.
• The test you don’t want: a sharp, immediate burning sting followed by small white welts.

In early spring the new shoots are short and tender, with leaves often tinged purple. They already sting at that stage, so gloves are a must even when the plant looks harmless.

Where it grows in Pennsylvania

Nettle wants moisture and rich soil. In central PA it thrives along streams and rivers, in floodplains, moist woods edges, drainage ditches and wet spots below hills. It’s also a classic weed of barnyards, old manure piles, compost heaps and anywhere organic matter has built up.

Around homes, it shows up in shady, damp corners, behind sheds and along the back edge of wooded lots. If a patch is creeping toward your lawn, the soil there is probably wet and fertile.

Stinging nettle look-alikes

Native wood nettle grows in many of the same floodplain spots and stings too, but its leaves alternate up the stem instead of pairing up. False nettle, another native, has similar opposite leaves but no stinging hairs at all.

Purple deadnettle sounds similar but is a short spring annual with pink flowers and no sting. Horsenettle isn’t a nettle; it’s a spiny nightshade relative with yellow berries.

The quickest clue is the leaf arrangement and the hairs. Opposite, toothed leaves with bristly hairs on a tall square-ish stem, in a dense patch near water, add up to stinging nettle.

How to get rid of stinging nettle

Suit up first: thick gloves, long sleeves and long pants. Then decide whether you really need to remove it. Nettle is food for several butterfly caterpillars, and a patch in a wild creek corner may be worth leaving.

• Dig it out: in spring, when shoots are small, loosen the soil with a fork and pull out the yellow rhizomes. Get as much as you can, since leftover pieces resprout. Moist soil makes it easier.
• Cut repeatedly: mowing or cutting the patch to the ground several times a season weakens the rhizomes and stops seed. It takes persistence over a couple of years.
• Smother: for small patches in beds, cut it down and cover with cardboard and a thick layer of mulch.
• Change the site: nettle loves wet, rich ground. Improving drainage and planting thick grass or groundcover makes it less competitive.

Herbicides: systemic products work best on actively growing plants in late spring before flowering or on regrowth in early fall. Broadleaf herbicides containing 2,4-D, dicamba or triclopyr can control it in turf or rough areas, and glyphosate works as a spot treatment but kills anything green it touches. Many nettle patches sit right next to streams, so the product must be labeled for use near water. Read and follow the product label, since the label is the law. Applying herbicide for hire in PA requires a PA Department of Agriculture pesticide applicator certification, so large or streamside patches go to a licensed vegetation-management company.

Keeping it from coming back

Rhizome pieces left in the soil will send up shoots for a season or two. Check the spot every few weeks in spring and early summer and dig or cut new growth right away.

Don’t dump fresh manure or rich compost at the edge of the woods, and keep the area mowed or planted. If a wet low spot keeps growing nettle, fixing the drainage is often the long-term answer.

For the area where kids play or dogs run, keep a mowed buffer between the lawn and any nettle you decide to leave in a wild corner. That way the patch stays where it’s useful and out of the way of bare legs.

Questions we get about stinging nettle

Similar weeds

HorsenettleSolanum carolinensePurple DeadnettleLamium purpureumJapanese KnotweedReynoutria japonica