They grow like weeds here! Slugs do love them, so it's important to take steps against those - we use mineralised straw mulch here, although I think it's not available in the US (or at least no one has told me it is). But any other method of slug control would work - so just do whatever you do for hostas or other vulnerable plants. Our soil is clay-based, but they grow in all soils except chalky. According to the RHS they like either neutral or slightly acid soil - our is alkaline and as you can see they don't seem to mind!
So the short answer is that I don't really do anything - I do cut down the stalks after the first flowering so they rebloom. If anyone is willing to register as a small quantity seed importer (I think it's done online and not too difficult or expensive) I would be more than happy to send you some seeds. Plants grown from seed will not be identical to the parent plant (as with irises) but all the parents are from Westcountry Lupins, probably the best lupin hybridiser in the UK (they decorated the royal barge for the William/Kate wedding). I have other lupins not yet in flower; I'll post photos when they are.
