No eggs

[Ladybluearm]

I have 9 young barred rock pullets, 21 weeks old, not laying yet. They are on laying pellets and have great laying boxes provided. Anxiously waiting. I thought they would be by now, what could be the problem. They are molting a bit.

 

[ChickenCanoe]

Molting first autumn isn't common but can happen. Molting will normally prevent laying since egg production and growing a new winter coat are difficult to do simultaneously.
All that said, it is most likely the time of year. You are in the northern hemisphere which means day length vis-a-vis dark period is changing the most at this point, just as in May day length increases dramatically. Increasing day length signals animals to reproduce. Decreasing day length is the sign to shut down reproduction.
Most modern breeds of chickens will lay right through their first winter once laying begins if it starts prior to short days.
When did you start feeding layer feed?
I normally recommend waiting till the first egg to switch to layer, especially in fall when there is no guarantee commencement of lay is imminent.
Birds not laying eggs, in spite of being female - are not layers and shouldn't get the 4% calcium in layer feed.
I'd get a little grower or all flock feed to switch them to temporarily. The higher protein will help with feather production and won't hurt onset of ovulation.
I would recommend reading the following article and check your bird's pelvic bones.
https://www.backyardchickens.com/articles/who-is-laying-and-who-is-not-butt-check.73309/

 

[Mrs. K]

21 weeks is still pretty early. And while breeds have tendencies, individual birds vary. And we are past the solstice. The days are getting short.

What I think will happen, kind of sort of, is no one will lay until much closer to 24-26 weeks, and they won't lay every day. It will be hit and miss, and some may not lay at all until January or February...depending on how far north you are.

And you could add some lights -but even with lights - I would not expect eggs for another 3-4 weeks. Are their combs bright red, swollen? Count 3 weeks from that. If you don't have a rooster, do they squat for you, and let you touch them, and then shake? Count two weeks from that.

But really until you have given up all hope, and are sure that somehow you got the few chickens in the world that don't lay, and have come to terms with that...3 weeks later they lay!

Mrs K