I planted about 20 Globemaster flowering allium bulbs last year. The display last year was great! This spring, however, some bulbs did not come up at all. Of some that came up, the foliage was brown tipped (I suspect frost damage...we had some very cold nights), but a few of the plants flowered and then collapsed. Does anyone know what is wrong? They just dont seem to be thriving. Also, I'd like to propagate them from the seed heads that are left after the flowering. Is this possible? Plant like onion seeds?