Horsenettle

Quick facts

For identification. Not a growing guide.

How to recognize it in each season.

1. 1

   Spring shoots from the root system (find it now)

   Apr to Jun, every year

   • Recognize it: prickles on the stems AND along the leaf midribs
     Shoots come up late, well after the first spring weeds, from roots rather than from seed - so they appear in the same spots as last year, often in a rough line. Look for straight yellowish prickles on the stem and, crucially, on the midrib of the leaf on both surfaces. Leaves are alternate, oblong, 2 to 6 inches, with a few wavy lobes down each side, and feel like fine sandpaper from a coat of tiny star-shaped hairs. Nothing else in a lawn or bed is armed on the leaf vein like this.
   • Dig small plants out whole - and never rototill a patch
     A young, isolated shoot can be forked out if the soil is moist and loose and you follow the root down and sideways until it ends. Get every piece: a fragment under an inch long, with one bud on it, makes a new plant. Do NOT pull - the root snaps and you have simply pruned it. Do NOT till or rotovate a horsenettle patch: chopping the root system is how one plant becomes fifty, and it is the single most common way gardeners make this weed worse.

   Key signs

   • Late-emerging shoots in the same places as last year
   • Prickles on the leaf midribs, not just the stems
   • Any resprout after digging - remove it the week it appears
2. 2

   White to pale-violet star flowers (the control window)

   Jun to Sep, every year

   • A tomato flower on a prickly stalk
     Flowers are five-pointed stars about an inch across, white to pale violet, with a protruding cone of bright yellow anthers - unmistakably a nightshade flower, and near-identical to a potato or eggplant bloom. They come in small clusters off the side of the stem from early summer into autumn, and bumblebees buzz-pollinate them. Once you have seen the flower there is no doubt what the plant is.
   • Cut or treat at full bloom, not before
     This is the moment worth knowing. At full bloom and early fruit, and again on fall regrowth, the plant is moving sugars DOWN into its roots - so anything systemic goes down with them. Cutting or treating in May, while it is still pushing growth upward, mostly wastes the effort. If you are mowing to exhaust it, cut every 2 to 4 weeks from first shoots until frost; one annual mowing achieves nothing at all.
   • Do not let it fruit where children, pets or hay are
     Everything that follows the flower is the hazard. In a lawn, play area, paddock or hayfield, cut the plants down before the berries form rather than waiting for a convenient day. It is far easier to remove flowers than to police ripe berries later, and berries cut into hay are the classic route to livestock poisoning.

   Key signs

   • White or pale-violet star flowers with a yellow anther cone
   • Plants flowering below mowing height in short turf
   • Flowers in a hayfield - cut before the fruit sets
3. 3

   Yellow berries - the poisoning risk

   Aug to Nov, every year

   • Strip and bag the berries before anyone else finds them
     Fruit starts green with pale marbling, like a tiny watermelon, and ripens to a smooth glossy yellow ball about half an inch across on a bare stalk. That is what a small child sees as a tomato, and it sits at knee height. Wearing gloves, strip the berries into a bag and put them in the trash - never the compost, where the seed survives and the fruit is still findable. Then deal with the plant.
   • Check hay, paddocks and anywhere animals feed
     Grazing animals normally leave the growing plant alone because of the prickles, so pasture poisoning is uncommon. The real risk is hay: berries baled with the crop lose their spines and their bitterness cues and get eaten with everything else. Walk hayfields before cutting and check bought-in hay for the shrivelled orange-tan berries and prickly stem pieces.

   Key signs

   • Glossy yellow berries about half an inch across at child height
   • Berries dropping into a lawn or play area
   • Prickly stems and dried berries in baled hay
4. 4

   Winter: dead stalks, shrivelled berries, living roots

   Nov to Mar, every year

   • Dead stems still hold fruit all winter
     Frost kills the top growth, but the stalks stand through winter with wrinkled orange-tan berries still attached - which is both a hazard and a gift, because a dormant garden is the easiest place in the year to see exactly where every plant is. Walk the ground, mark or flag each stem, and bag the old fruit.
   • The roots are alive two to three feet down
     Nothing above ground reflects what is below it. Horsenettle overwinters as thick, fleshy, creeping roots that run several feet sideways and two to three feet deep, carrying buds along their whole length, and they resprout regardless of what happened to the top. Winter is for planning a two-to-four-year campaign and for keeping the tiller away from marked ground, not for a quick dig.

   Key signs

   • Standing dead stems with shrivelled berries
   • Marked patches to keep out of spring tillage
   • New shoots appearing late the following spring

Watch out for

4 to know. 2 are high-risk: Regrowth from Deep Creeping Roots, Toxic Yellow Berries. 4 are active in September.

Good & bad neighbors

First rule: keep Potato apart. A genuine conflict, not folklore.