Never seen it get more than 3 feet myself, even in optimum conditions.

umm yes i think some sellers are misleading

Ours grow to about 4. The fertility of the soil can have an effect as they atre greedy feeders; not that ours ever get fed!

Is it right that you plant the bulb upside down or on it's side so it doesn't rot?

yes until the bulb gets established to stop the top rotting and will right itself in the end

No, Ladye, I have never done that and have no problem. Our soil is very well drained, if you garden in a heavy soil (eg Essex?) it may be different.

mine got to about 3.5 ft and I put them on their side when I planted them. when I accidently dug one up it was the right way up. I wouldn't put it upside down as that is quite a turning act for it.
I don't bother now they go in the right way and don't seem to have a problem.