Hi,could any one tell me when the coat for a long haired gsd develops.I have what i thought was a longcoat pup but he is nearly 6 months old and his coat doesnt look too long to me.Also when do they usually stop growing upwards as he is only about 23inches at the shoulder and appears quite small,thanks.

There are three types of GSD coat. The Stock (standard) coat, the Long Stock coat (with undercoat) and The Long Haired (no undercoat)
If your pup has tufts of longer hair on it's ears, that's normally a good indication of a coated dog.
When my dog was 6 months old, apart from those tufts on his ears, he'd have gotten away with people thinking he was a plush coated dog...which is just a term used for a slightly fuller Stock coat.
His chest, belly and pantaloon feathers took a while to become the length they are now :)
Were one or both (or neither to look at) of your pups parents coated?

As for his height, he'll get there. By about 9-10 months they've probably done growing upwards and start instead to fill out. Maturity however, takes a little while longer ;)