Hard shell gourds are popular for crafting into bowls, birdhouses and other holiday novelty items and figurines. These gourds grow on one main vine plus leaders. If you cut off the end of the main vine, explained Soehnlen, the leaders will shoot out. Hard shell gourd vines develop white blossoms that open at dusk. Different hard shell varieties will cross pollinate, so be careful about mixing these seeds.
Hard shells develop a nice, mottled green color and can grow quite large and heavy.
They can be encouraged to grow straight or develop interesting curves. For straight gourds, grow them on a sturdy trellis, allowing them to hang down to develop long necks. For curves, grow them on the ground. In addition, hard shells grown on a trellis add shade value, explained Soehnlen. By September, the vines of both hard and soft shell gourds are dying back, and the gourds are fairly mature and ready to harvest.