What has happened to Ferocacti I put in too much shade is that if they do grow they tend to really show low light effects in their spines - spines go super thin to non-existent. I have a F. latispinus that clearly is it because of the body and older spines but if I'd just show pictures of the youngest spines you'd not ID it as such. Problem is that F. latispinus is not quite able to deal with full sun here, many Feros are, so if you like me have most full sun planting spots or if there is shade most full shade then it is hard to get that plant to be where it is happy.
It might still grow just fine, but it will not look like it is normal impressively spined self.
