Bulbs would only provide temporary erosion control. After they go dormant, the roots disappear as well, so you'll be back to the original condition. You need a perennial groundcover for the growing season, or an evergreen groundcover for year long control. Check the perennials forum, explain the conditions of your site when you post. Sun/Shade, soil type.

Paula,

Thanks, I understand that - the rocks and the soil, once they're both settled, would provide the major source (in fact, now that I think about it, it all would be provided by the rocks) of soil stabilization.

I guess I should have phrased my question like this - are there bulbs that favour a confined space, once mature (that is, in the ground for several years)? I'm planning on sinking the rocks fairly deeply, so the bulbs that I put inside the rock formation are not likely to expand outside of the formation.

I already have lots of bulbs (tulips, lilies, hyacinths and muscari) in the ground, but wanted some different ones along the embankments that will fill in nicely with the rocks and don't have to be pulled up for our winters here.
Maybe I should consider a few perennials, but I'd prefer bulbs, for some inexplicable (for now) reason.

Thanks again for your thoughts.

Although not bulbs, daylilies are an excellent choice for erosion control. Otherwise, if that is not a major concern, lots of lesser bulbs are happy in confined spaces and many are native to rocky areas or are used extensively in rock gardens - scilla, winter aconite, species tulips, Chionodoxa and snowdrops would all work. Crocus certainly. Erythronium in shadier areas.

And I would also consider perennials, groundcovers or other rock garden plants. Nothing looks worse than a dedicated bulb planting area after the bulbs have finished blooming -- you need something else to carry you through the seasons.

Have you enough space for your low-growing Mahonia and that, is it kinnikinnick? I saw growing in an alpine area. It has terrific autumn colour.

Other possibles - Aquilegia canadensis? Some of the fritillaries? Sanguinaria? Dodecatheon?

And, if there's a suitably boggy spot at the foot - Sarracenia, perhaps? Amsonia?

Is your embankment in sun or shade, dry or moist? Botanical or species tulips such as tulipa tarda (yellow) like a sunny, dry (in summer) site and multiply quickly. Scilla siberica (blue) also spreads quickly, by seed, and will grow in a sun or part shade situation. For summer flowers, you could add some alliums, e.g. the native allium cernuum (pale pink). There are many choices. It just depends what you like. Crocus might be eaten by squirrels or rabbits.