An import permit is not required for importing small quantities of "bulbs" by
the United States Department of Agriculture (USDA) unless you are importing in
commercial quantities.

All plants, bulbs, and seeds must be accompanied by Phytosanitary Certificates
from the originating country. Correct identifications of all materials with the
botanical names, including both Genus and species names, are required. The
requirements are actually quite easy to satisfy.