If you need eggs, all of them; if you need chicks, none of them.

What i dont get it.

Hens will do what hens want to do. I think that's what fancifowl meant, and it's true.
There are breeds that are more broody than others. You can count on Silkies hatching eggs. But even with them, if you have some eggs that must be incubated, they might decide they don't want to brood eggs that week.
Once a hen does goes broody, there isn't much you can do to talk her out of it.

*L* fancifowl is exactly correct--when you want to hatch chicks, NONE of your hens will cooperate and go broody. If you want EGGS, they will ALL go broody and stop laying. It's one of those 'Murphy's Law' type things. Obstinate little stinkers...!

Springtime usually naturally brings a desire to go broody in some hens, depending on breed. Silkies, cochins, banties and 'fluffy' (heavy) breeds such as Orpingtons tend to go broody more reliably and easily than other breeds. Breeds such as Polish, Rhode Island Reds and Leghorns have mostly have the broodiness bred out of them in favor of laying eggs.

And hens will go broody whenever the mood strikes--some do it for a few days, others for weeks on end--eggs or no. Broodiness cannot be forced. If you can tell us what breeds you have, or post pictures, we might be able to give you a better idea of what you can expect.

You can help encourage broodiness by providing lovely nesting areas with plenty of nesting material and make them nice, quiet, darkened, private nests where the hens can set undisturbed. Away from dogs, kids, noise, etc. Broody hens like to feel like they are safely 'hiding' their nest away from predators, it's instinctual. Leaving a couple of eggs in a favorite nest can help, too--just make SURE to take a pencil and mark the eggs to be left with an 'X' so that they get left behind and fresh eggs picked up--you don't want to accidentally crack open a week-old egg that's been sitting out! *L*

Velvet ~:>