Forced bulbs, which is what your hyacinth is, will grow if planted outside.They generally won't do as well as those bought for that purpose, but sometimes you get lucky. Plant it out now, loosening the soil to about 8 inches, and plant it about 6 inches deep. Leave the leaves on, but cut the flower stalk off. Feed it a good quality fertilizer now, and water well. Then forget all about it until next spring, when with luck, you'll get to enjoy it again!