Surrey,
United Kingdom 
HELENIUMS i love tall plants but heleniums dont always come tall i looked at "The bishop" as it was claimed at wisly they grow it as a hedge in summer it gets up to over a metre ive seen it! they said it was "The bishop" and a lot of places say 100cm but i went to a specialist and they say only 60cm ? and if you look at google photos it appears short
10 Apr, 2016
Answers
Try this website http://www.helenium.net/helenium.htm
I find it invaluable for researching heleniums.
10 Apr, 2016
Hi I have Moorheim Beauty which grows quite tall, but may need staking, I usually 'chelsea' chop mine back so it's a bit shorter :-)
11 Apr, 2016
I've found it listed in 4 different places as being up to a metre tall, including the RHS, so I'd go with that information - it may vary in height depending on cultivation (soil, light, water, etc). Not sure I'd be buying from the specialist you mention though, not sure I'd trust the plant they're selling under this name.
11 Apr, 2016
Hi, if you're looking for tall Helenium some suggestions below;
species growing to 5ft tall, H'Feuersiegel' H 'sonnenwunder' H 'Septemberfuchs' H 'Goldrausch' H 'Feuersiegel' H autumnale, species growing up to 4ft, H 'Baudirektor Linne' H 'Bruno', H 'Riverton Gem' H 'Rotgold, H 'Zimbelstern',
but they will only achieve these heights under ideal growing conditions, and are mature plant sizes, Derek.
10 Apr, 2016