All ium schubertii is a bulb and a perennial. However, it does have a habit of reaching flowering size and then resting for a season before flowering again. Really well fed from when the leaves first appear until they begin to die down would help repeat flowering. Obviously if the planting position is not to the plants requirements then they might flower once from planting and then die altogether.

Many thanks Owdboggy for that comprehensive answer.

Good q drakey can I ask - I want to plant my alliums as suggested amongst shrubs so how do I feed them owdboddy

Easiest way is to put some bone meal or Blood fish and bone or general fertiliser in with the soil when you plant them. Remember that a handful of Bonemeal or BFB is supposed to go over a square yard so for a small amount of soil you only need a pinch.
If your soil is in good heart (and you can tell if your shrubs are good and healthy) then feeding the bulbs is not really necessary. It is only in poorer soil that there could be a problem with repeat flowering. I assumed (probably erroneously) that the question was asked becasue of some difficulty with them growing previously.
Amongst shrubs is a good idea, as long as the top of the bulb can get some sun in the Summer to help ripen it. Drainage is the most important thing for all these big Alliums. They hate sitting in water. Remember many of them come from Tundra where, the top foot or so of soil is well drained in Summer and below that it is permanently frozen so they are not sat in soggy soil.

Thanks owdboddy.Our garden would have been a grazing field for the owners horse at one time. We found and kept all the field drains intact. The last owner before us had loads of peat delivered and did not mix it in sufficiently for it to improve the soil. Because we used to be under the main approach to a national airport we had no worms. Every time a plane went over the worms came to the surface and got snapped up by the birds. To remedy this, every year for seven years, I got a load of well rotted farmyard manure (dung) from the local dairy owner. He thought I was growing mushrooms. I grew all the veg we needed and then health problems caught up. When I was lifting my Golden Wonders in March instead of planting them I called it a day and my husband laid it out in lawn. I grow in buckets now. I just need to upturn them to enjoy a good crop of potatoes.