Thalia Red StemText Box: THALIA RED STEM (Thalia geniculata) Large leaves are supported on red stems. Can grow to 5 ft. Water depth 2– 6 inches. Flowering spikes up to 10 feet. Weather permitting we ship the tropical marginal and bog plants April through September. OUR MARGINAL AND BOG PLANTS ARE EITHER IN 2 INCH POTS OR BAREROOT Tropical marginal and bog plants will not survive the cold temperatures, if you live in zone 7 and below you might consider them to be annuals or bring them indoors in the winter.