This is a very interesting and wonderful plant that has become more widely available in recent years and with it comes an interesting controversy: The original description of the plant by Howard S. Gentry would appear to only include room for the white-grey version of the plant to be the actual true form of Agave titanota.

However, as one can see from the photos for this plant posted in the database there are green versions that otherwise look very similar to the white-grey versions that you can find at botanical gardens and nurseries also named Agave titanota. While work is in progress to try and sort out if these green plants are indeed just green versions of Agave titanota or represent something different: either a hybrid or a completely new species, the fact that these green plants are very variable and some times can be grown from seed that purportedly came from the white grey form, makes for a complicated situation.

Interesting tidbits that I have learned from people who have actually visited the type locality of Agave titanota as described by Gentry and where he collected his specimen plants: Within the area of the type locality no green plants where observed, the white grey plants there appear to grow only on limestone substratum. The first green look-a-likes are encountered a significant distance away from the type locality in an area where they are close to and overlap with other Agaves, significantly among those another quite variable Agave: Agave kerchovei. These plants are growing on mixed substratum not solely limestone, and while most are green there are blue/grey-green plants among them.

So the jury is still out, but if you are growing and enjoying a nice green 'Agave titanota' do not be surprised or upset if there are certain purists around that would strongly disagree with that plant as being an actual Agave titanota.

As to growing them: here in Mesa, AZ, where we get to deal with the full on AZ summer and a strong heat island effect these plants enjoy a little bit, but not too much shade to look their best. So in areas where the summer is less extreme these plants should have no problem with full sun. Plants enjoy regular summer water and would probably not mind some limestone soil amendment. Since it has not really been very cold here during the winter in quite a while, I cannot speak to this plant's cold hardiness.
Both my white grey and my green specimens offset regularly when the plants are settled in and happy, most of these offsets are basal stem offsets though and they are not that easy to remove, but offsets should have no problem rooting.
As plants mature they appear to slowly but surely become less fierce looking, with the extremely toothy leaf margins becoming much less so.

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