What broodiness is, and why it will not just fade
A broody hen has switched into incubation mode: she flattens herself over the nest, clucks softly, puffs up and pecks at hands that reach under her, and leaves the nest only briefly to eat and drink. She will sit on fertile eggs, infertile eggs, or no eggs at all with equal devotion, because the drive is hormonal, not logical. Left alone she may sit for three weeks or longer, losing condition, barely eating, and stopping laying the whole time — while also occupying the nest box your other hens need. Breaking her up promptly is kinder than letting her waste away on an empty nest.
First moves: eggs away, hen off the nest
Start with the simple pressure. Collect eggs several times a day so there is never a tempting clutch building up, including from any hidden corners she might adopt. Every time you find her settled, lift her off and set her out in the run near food and water — some hens only need this repeated eviction for a day or two. Shutting her out of the hen house during the day, where that is practical and safe, removes the nest from the equation entirely. Watch that she eats and drinks at these evictions; a hen growing light and listless needs the stronger method below without delay.
The broody crate: cool air where she wants warmth
The method that reliably works is a crate or cage with a wire or slatted floor, raised on bricks so air circulates freely underneath. A broody hen's instinct is driven by warmth against her breast; a floor she cannot warm up, with cool air flowing under her, switches the instinct off. Put food and water in the crate, set it somewhere bright, safe from predators and in sight of the flock, and leave her in it day and night for a few days, letting her out only to test her. Most hens are broken in two to four days. She has no nest material in the crate — comfort is not the point; the cool underside is.
Testing whether she is truly broken
Each day, let her out and watch where she goes. A hen still broody marches straight back to the nest box and flattens into it within the hour. A broken hen scratches, dust-bathes, feeds with the flock and roosts normally at night instead of returning to the box. Only when she roosts on the perch like everyone else is she finished with the crate. Expect her to start laying again a week or so after she gives up sitting, and keep collecting eggs promptly for a while, since a hen that has gone broody once is a candidate to try again in the next warm spell.
Prevention, and the checks that make it stick
With a known broody-prone hen, prevention is mostly egg discipline: no eggs left sitting in boxes through the day, no cosy hidden corners, and golf balls in the nest are an invitation, not a deterrent, for her. The whole break succeeds or fails on consistency — one day forgotten in a warm nest can reset the clock, which is why the daily lifts, collections and crate checks suit a shared rota. Recording those checks in KinsLe Care Teams, each one marked done with a timestamp, means everyone helping with the flock knows whether today's egg collection and broody check actually happened.