You Will Get 5 Seeds Yucca Rostrata Blue Beaked Yucca Hardy. This great yucca gets evergreen foliage, and clusters of white flowers, like nearly all yuccas, but the leaves can be a bit more blue on this species.. The one really great characteristic of this one is that it can produce a trunk of 4’ to 6’ or more, although they do grow fairly slowly.. These plants are extremely exotic, yet they are very cold hardy, provided that they are kept dry in the winter.. They are hardy to at least USDA zone 5, and possibly colder.. These plants would make excellent additions to your rare plant collection, or just make a unique statement in your yard.