That is a very good idea !!

I've got a bright green shag carpet of nigella seedlings. AND they are completely winter hardy, so I'm guaranteed plenty in the spring, whether I want all of them or not (they can get kind of aggressive, but they're easy to remove where they're not wanted). I'm also getting malva 'Zebrina' seedlings now, but they are NOT winter hardy. I always have plenty of self-sown ones every spring. I winter sowed them my first year, and haven't had to do them again since then. Laurel

I would look at the root shape. Roses kind of form a heart. Bulbs go pretty much straight down. So you'd want to put the bulbs in a space between the space the roses need. A ground cover like alyssum keeps its roots near the surface, so they won't fight with the rose, and they can be planted closer. Search for "root system" and whatever plant you're thinking of, and you'll get images. Imagine how they'd share the underground volume, give each plant its part, and they'll be happy.

At the old house, I had a ton of blue flax that re-seeded like crazy. You couldn't really deadhead it, because it was constantly making new blooms on the same stems, so it gradually took over much of the front garden. Which was a shame, because the petals would usually have fallen by the time I would get home from work in the evening! So, while I did like them, I didn't bring any seed to the new house - just too much of a good thing after a while. At the new house, I'm not sure yet which will be doing that much re-seeding. I'm trying to keep on top of shearing my nepeta so it doesn't self-seed too much. I like lambs ears foliage but not the blooms, so I have been cutting them back. I have a little bit of larkspur - I actually shook them all over last fall before composting them, since I didn't have a whole lot to bother harvesting the seeds. I refuse to ever plant echinops. After fighting to keep out the invasive thistles at the old house, I could never get myself to purposefully plant anything thistle-like! Ouch, ouch, ouch...