Red ginger (Alpinia purpurata) is a tall, herbaceous perennial, grown for its bright red plume-shaped flower bracts. Native to the South Pacific, it is widely cultivated as a landscape ornamental and also grown commercially for cut flowers. This distant cousin of edible ginger grows from spreading, underground rhizomes, which must be accommodated in pot culture. When your red ginger plant needs re-potting, you can keep the plant healthy and propagate new plants by following a few easy steps.
Spread several sheets of old newspaper out onto a work surface. Tip your red ginger plant out of the pot onto the newspaper and carefully brush the soil away from the roots.
Divide the matted roots into clumps of one to four stems using the sharp knife. Trim off the green stems of any clumps which lack developed roots protruding from the fleshy rhizomes.
Wear gloves and dust the cut rhizomes with sulfur powder or other fungicide, using care not to inhale the powder or get it on your skin.
Bury each rhizome clump 2 inches deep, in a 6-inch pot filled with vermiculite or well-draining potting soil. Water the soil thoroughly at planting and keep evenly moist until new growth appears.
Place your red ginger roots in a warm place out of direct sun until they are well-rooted and have at least four healthy stalks. Gradually move the red ginger plants into more sunlight. Transfer them into a sturdy three-gallon, or larger, pot to grow them indoors. Plant them outdoors in a sheltered location with full to partial sun in frost-free areas.