Toby (Hi again, two mails in one day from me!!)
Sarracenia Nurseries believe that you can enhance colouration in Sarras,
particularly red veining and similar, by placing an iron nail in the soil.
Presumably any iron additive would have the same effect.
As to me, I believe there are lots of spurious "red" or "burgundy"
plants that aren't. They may occassionally put up red coloured pitchers
but I've seen many that revert almost immediately to green. So the best
remedy is to find a better clone!
Then again, I'm not a sarra expert by any means so lets see if an expert
responds!
Regards
paul