If winter dryness turns the topsoil to dust, that means trouble. And during the plant's active growth period from April through June, keep pouring the H 2 O on. As with other garlics, cut back on water in the several weeks before harvest. And they do enjoy nitrogen feedings during the spring. We also condition the soil with a lot of well aged manure.
Bone meal seems to help, too.
A late spring field of elephants is an impressive sight, with their luxuriant blue green foliage. And come June, up go the scapes, ready to produce a beautiful purple flower characteristic of the allium family. But few of ours become so adorned because we cut the scapes just as pods form. We find that this does increase bulb size. Soon after, leafy growth ends, and bulb formation is in earnest.