- You Will Get 25 Seeds Of Soapweed, Yucca Glauca White Flower Seeds. - Perennial. - White blooms. - Grows 4 ft tall. - Full sun. - Hardy to zone 3. - Soapweed, or Yucca, grows long straight needle like foliage and produces a flower spike up to 4' tall with white blooms that appear in May and June. - It is a striking and somewhat exotic looking plant.