Lafayette County Master Gardeners: Curcuma Ornamental Ginger

Curcuma Siam Shadow. Photo by Bronwynne Bailey

There are forty-seven genres and more than a thousand distinct species of ornamental ginger plants. There is great variation among species with presentations that look like pinecones, pineapples, mutant orchids, or alien insects. A visit to Hawaii will provide you with a large variety but most are not native.

Colors and Varieties
Norman Winter (from Central Mississippi Research & Extension Center) provides the following recommendation for Mississippi gardeners:

The scarlet ginger is very exotic looking with 10-inch-long orange to red floral spikes produced on 6- to 7-foot canes. The blooms do not last exceptionally long but produce for a long time.
The crepe ginger (Costus speciosus) produces white flowers in a 4-inch bracted red cone. After the flowers have dropped, the red bract cone remains pretty for an extended period of time, like the way the yellow shrimp plant performs.
For fragrance, you should buy butterfly ginger, Hedychium coronarium. The white, butterfly-shaped flowers produced this time of the year are full of fragrance. The plant is one of the easiest to grow and hardiest for Mississippi.
My favorite is the hidden ginger or Queen Lily, Curcuma petiolata. With canna-like leaves, this plant produces one of the prettiest blooms rivaling the bird of paradise, heliconia or bromeliad. Tucked down in the plant, the flower is quite showy. This variety may be invasive so avoid planting along native areas to prevent unwanted spread.
The variegated shell ginger Alpinia zerumbet variegate has leaves with a green and zebra-like band of creamy yellow. Although they bloom from time to time, the foliage is the showstopper! In Zone 7-8, you may want to dig it up and grow it in a container during the winter.

Growth Habits
Temperatures below 50ºF will spell trouble for a ginger flower. This limits outdoor growing as a perennial to hardiness zones 9 through 11 unless you have a heated greenhouse. Expect an average growth size of two feet wide and four-to-five-feet height.
It is important to note that though they smell remarkably similar, ornamental ginger plants do not yield the ginger root we use as a spice in the kitchen. Those are commonly referred to as culinary ginger plants, and they have their own species classification called officinale. Most ginger rhizomes you purchase in the grocery section are treated to limit leaf production and are not likely to root.

Butterfly ginger. Photo by Norman Winters

Soil Preferences
Tropical plants need tropical growing conditions, so before planting any in your yard, you will need to evaluate your surroundings closely. Moist, well-draining soil is ideal. Ginger prefers a neutral to slightly acidic ph.

Planting Depth & Spacing
Size and shape vary depending on the variety. For practical purposes, leave plenty of space between plantings. Most ornamental ginger plants produce exceptionally large blooms and grow to be quite tall. Ornamental gingers do not need harsh direct sunlight; they perform better in a little bit of shade.
When potting, select a container at least two feet wide and deep because the rhizomes will grow and replicate throughout the growing season and because the ginger will grow at least two feet tall and need a solid base to prevent destruction from winds.

Watering
Ginger needs at least one inch of water per week. Monitoring weekly rainfall is critical with supplemental watering as needed. Drought conditions with deeply limit flowering.

Fertilizing
As for fertilizer, Cooperative Extension Service recommends a biweekly or monthly application with a high-nitrogen content to increase blooms.

Pruning
Remove spent flowers down to the ground but allow leaves to die off naturally as pulling them can damage the rhizome. Preserve rhizomes in peat moss of sphagnum moss to overwinter. You can leave ginger in pots to overwinter. Store in a cool dry place. Avoid humid areas such as kitchens and restrooms.

Propagation
When slicing off rhizome pieces, make sure each new piece contains more than one node. Since you will not be eating the roots of ornamental ginger, you can immediately plant each piece in a tall grow pot. Use a rich, well-draining growing medium and bury the baby rhizomes deep with the nodes facing up. Water generously, keep warm, and wait three weeks before you expect to see signs of healthy new plant sprouts. Professionals can propagate via seeds.