Are they reliably perennial or invasive? In ideal situations, old fashioned grape hyacinth, Muscari armeniacum, can get a bit too eager to proliferate and migrate. Not only do their bulbs divide efficiently, but their seed disperse beyond bulb colonies. However, bulbs do not migrate too rapidly for containment. Thorough deadheading inhibits seed dispersion.
Grape hyacinth provides some of the earliest spring bloom. Floral spikes of tiny rounded flowers do not get much more than six inches tall, but are delightfully abundant. The rich blue color is exquisite. Hybrids and other species can bloom with pale pink, pale purple, white, yellow, or various shades or tints of blue. The grassy foliage is somewhat rubbery.
If they do not migrate efficiently enough, established colonies of grape hyacinth are easy to divide in autumn. Of course, it will be necessary to mark their locations as their foliage dies back at the end of spring. Division is easier and faster than growing new plants from seed. If hybrids produce seed at all, it may not be viable. If it is, it may not be true to type.