Alliums are tremendous flowers for the border, with the taller stemmed varieties making a wonderful punctuation to the summer display.
These can be planted later than some other Spring-flowering bulbs, and are often offered alongside the autumn and summer-flowering bulbs/tubers (such as Dahlia), however for the best results these should be planted in the autumn.
Plant these quite deep – usually the depth should be twice the height of the bulb, but they can be shallower. In time the bulbs will find their own place if they are planted too shallowly to start with. Good or normal drainage is ideal, avoiding wet soils.
Allium nigrum is one of the sturdiest and offers excellent value for money. The flowers are white, but the seed capsules go a darker color as they mature, hence the latin name.
Allium christophii is another fine variety – the stems are short but the flower heads themselves are quite large. Not as large as Allium schubertii, but they have a deeper, richer colouring. Allium schubertii is also a great variety for a sunny spot, with seed-heads that look like massive dandelion seedheads when they finish flowering.
One of the best modern hybrids (and great value for money too) is Allium Purple Sensation. These grow nice and tall, and can be used for cut-flowers (but remember that they will smell of garlic). The plants are very sturdy, and will come back year after year, however you should make sure they get a good feeding in the early Spring.