I am not an authority on the subject,but from observations
of the genius as a whole. Climate in general plays a key role in a plants stature. I have seen the same cultivar
in different climates be variable in size. You may compare
notes with Robin Middleton in the UK. I am also sure being
grown from seed will have some impact the variance in the size discrepancy your having.

There are short forms of Salvia sclarea in the trade. Jim & Jenny Archibald have collected a giant form of sclarea in Turkey and it was released many years ago through the Denver Botanical Garden as a secondary US source as well as their list.

Thanks Hybridsage and Rich. Is the giant form commercially available? - it sounds nice.

What you are both saying sounds like sense. I read a book on genetic variability of natural species a while ago. It made the point, which is fairly obvious in retrospect, that the definition of a species can be rather a grey matter, rather than black and white. Surveys by the author and others showed that within a species there could be considerable variation in size, leaf shape etc according to the conditions where it was growing. But a lot of this variation was maintained when seeds from these differant plants were all grown together in trial beds, indicating that this variability was genetic.

Check JJA Seeds you will need to contact them see if they
have some available yet.

Thanks hybridsage - I have just had a look at their site, which is new to me, so I have saved the address. They don't have any on offer at present, but I will watch the site and see what Salvias they do have. As I already have a normal sized S sclarea, I can't, in all honesty, put it at the top of my list at the moment. But I might be tempted by something else!

I have just had a closer Google of JJA seeds and they appear to have a rather poor feedback.

Seed collectors operate on a seasonal basis. They are probably out in the field harvesting seeds, either in their own gardens or in the wild. This is the case with Southwestern Native Seeds. The latter have several times of the year when they are not available for correspondence. It may take J&J a while to answer mail, but they are very reliable and well known and respected by rock garden enthusiasts.

Thanks Rich. It looks a good site for seeds, and that has put my mind at rest. It fits with half the feedback saying very good, and the other half saying they couldn't be contacted.