I planted some bulbs this past fall and I know that most of them will only last until early-mid june. Are there any annuals I can plant once they are spent that won't harm the bulbs?
If the new plant is an annual, when it dies, it will decay and fertilize the bulbs. I don't know of any plant that is actually 'harmful' to bulbs. Just be careful that you don't accidently disturb the bulbs and don't cut off the bulb foliage - it needs to die off naturally, to get the energy it will use to bloom again next year.