Yes, the hardy begonias are great, but leave bare ground from the end of bulb season until mid-July when they start coming up for me here in central New Jersey. Have you tried interplanting late sprouting bulbs? Arisaema candidissimum, Arisaema consanguineum, and Amorphophallus konjac work well for me here, although the Amorph' has become somewhat of a pest. Watch out for "thuggish" groundcovers like silver Lamium or sweet woodruff, Gallium. They come up early in the year and stay low UNLESS they come up against a taller growing plant, in which case they try to compete in height, often by leaning against the growth of the victim for support. The sweet woodruff also I found is immune to slugs, but hosts them quite well. Perhaps they feed on the dead leaflets near the stem bases, but anything else coming up through them that is not rapidly sprouting and holding its leaves above the groundcover leaf level is quickly lost. By this I mean mature Arisaemas and Trilliums with leaves high up on the stem. Seedlings and low leafed plants are smothered and eaten. Bonaventure Magrys Cliffwood Beach, NJ USA zone 7