Answer: Your bulbs will most likely be fine if their depth isn't deeper than 12" deep. Planting depths given by bulb suppliers are generally for folks who intend to "lift" the bulbs. If your bulbs are naturalized, i.e., you leave them in place season to season you can add approximately 3-4" of depth to the supplier's recommendations. If the added top soil puts them much deeper than 12", I would probably dig them and replant at a lesser depth.
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