70-77 Days to maturity. Alternanthera dentata. Alternanthera Purple Knight Seeds. Non-GMO, Annual or Perennial. Purple Knight Alternanthera seeds promise an exotic and neat ornamental foliage ideal for many humid gardens across North America. Purple Knight seeds mature into robust mounded shrubs of rich purples and reds unfurling out for an eye-catching trim along walkways, borders, and fences. Alternanthera is native to the year round warmth of Asia, Africa, and Australia and will thrive all season in similar climates. Purple Knight alternanthera is easy to grow from seed and guarantees a unique and low-maintenance ground cover for any residential or commercial property.