How To Grow And Care For Curcuma (Turmeric)

Curcuma is a genus of plants native to tropical regions of Asia. You'll know curcuma, which belongs to the ginger family Zingiberaceae, by their eye-catching cone-like flower spikes. Tiny yellow or white flowers emerge from the colorful bracts on these cones. Some are called hidden cone gingers and have flower spikes hidden under the foliage. These highly ornamental plants include wild turmeric and Siam tulip plants.

Curcuma bloom in summer or sometimes fall, depending on the variety and the length of your growing season. Showy blossoms appear on the plant's lengthy stems, along with very long, lance-shaped leaves that resemble a canna lily. The leaves can be green, variegated, or have a central red stripe and grow from 18 to 40 inches long. This herbaceous perennial grows rapidly during monsoon season in its native habitat, then goes dormant during the dry winter. In a more temperate climate, it can shoot up 2 to 7 feet tall in the late spring and summer, then die back after a frost. Curcuma bulbs are planted in spring after all danger of frost has passed. These plants can be reliably grown in the Coastal and Tropical South and are often found along the Florida coast. Gardeners in the Lower South also can plant many Curcuma species and enjoy their tropical flavor in the garden.

Plant Attributes

Curcuma Care

Curcuma is relatively easy to grow indoors and outdoors as part of the ginger family. Depending on your climate, grow curcuma as an annual summer plant or as a tender perennial. The plants emerge late, with warm temperatures and lots of moisture. Curcuma prefers to stay drier in the winter while dormant. Some species like to receive hours of morning sun, while others prefer light shade.

Light

Common turmeric (C. longa) can handle full sun in moist settings but does especially well with direct sunlight in the mornings and afternoon shade in the South. Most curcuma do well in part shade or in light shade all day—for example, dappled sunlight or high, open shade.

Soil

The most critical factor in curcuma's soil is that it is well-draining and moderately moist while the plant is actively growing. Adding organic matter before planting will help achieve a loamy texture and enrich the soil. Curcuma prefers slightly acidic soil.

Water

Keep the soil moderately moist to ensure curcuma doesn't dry out while it is actively growing. Typically, this plant needs watering once weekly in the spring or summer, but this could be more frequent in hot weather during dry spells. Water any time the top inch of soil is dry, fully saturating the soil. Reduce watering during dormancy in the winter and early spring.

Temperature And Humidity

On the cooler end of its range, curcuma often waits until summer to emerge from the soil. In warmer areas like Florida, curcuma emerges in spring. Curcuma grows and flowers best in warm, humid growing conditions with ample rainfall. Plants go dormant in cool, dry weather and the foliage will not survive past the first frost. The foliage will sustain damage anytime the temperature drops under 50° F. Most curcuma are winter-hardy in Zone 8a or 8b and further south, though there are exceptions. If curcuma is not reliably cold-hardy in your area, you can grow it as a summer annual, store the rhizomes over winter, and replant the following year.

Fertilizer

Use a 20-20-20 soluble fertilizer after the shoots emerge in spring. Curcuma requires a lot of nutrients, so monthly fertilizing in the spring and summer will help encourage growth. Don't fertilize in fall or when the foliage is beginning to die back, as the plant is in the process of going dormant.

Types of Curcuma

• Siam tulip (C. alismatifolia): Siam tulip has smaller leaves and pink or white bract clusters. Plants grow to about 2 feet tall. 'Bangkok Ruby' and 'Twitter' are dark pink cultivars.
• Giant plume ginger (C. elata): Giant plume grows to 7 feet tall under optimal conditions and produces pink and yellow flowers. The flower spikes emerge from the ground under the foliage.
• Turmeric (C. longa): Turmeric cones can be white, pale pink, magenta, or ruby red. Plants grow to 4 feet tall and may be hardy to Zone 7b. After dormancy, the rhizomes can be dug up, dried, and ground into turmeric spice. You can also use fresh-grated turmeric in your cooking.
  
• Queen lily ginger (C. petiolata): This is the best-known variety of the curcuma, also known as hidden lily or queen lily. These plants grow to 3 feet high, with white, hot pink, or purple cones growing in the middle of the foliage.
• 'Emperor': This popular selection produces gray-green leaves with white borders alongside light pink flower spikes. These are, in a word, stunning.
• Zedoary (C. zedoaria): This species has green leaves with a dramatic, dark red stripe down the center and grows to 3 feet. The reddish-pink cones have bright yellow flowers. The rhizomes can be used in cooking.

Pruning

Prune in the fall after the foliage dies. Deadheading flowers is optional but can be done to improve appearance. Curcuma grows and blossoms even if you choose not to deadhead flowers. Use pruning shears to cut the flowers close to the ground and remove brown leaves when the plant does dormant.

Propagating Curcuma

Propagating curcuma is possible through dividing rhizomes. Curcuma's large rhizomes fill containers quickly, requiring division every two or three years. In the garden, dividing every three to five years will enhance the plants' vigor. Dig up roots in the fall at the end of the bloom season. Here's how:

1. At the end of the season, dig up the curcuma roots—you can tell the blooming season is over when the leaves start to turn yellow.
2. Choose healthy roots and avoid moldy, shriveled, or rotten ones. Divide the rhizomes with a sharp garden knife, making sure there are at least three to five eyes on each section.
3. Clean dirt from the rhizomes, pack them in sawdust or peat, and keep it in a cool, dark, and dry location until you are ready to plant it—usually in the spring.
4. Divide the rhizomes into sections, and leave a few "eyes" or buds in each section to help secure the roots when planted.
5. Plant the rhizomes in a container 2 inches deep or in the garden in 2 to 4 inches of organically rich soil. Leave the "eyes" or buds facing upwards. New growth should sprout outdoors by the following summer.

If you want to divide a large clump and replant it immediately, you can divide the plants in spring or summer. At the cooler end of curcuma's range, rhizomes should be planted at least 4 inches deep. In a mild climate like Florida, you can plant them 2 inches deep.

Potting And Repotting Curcuma

Curcuma is easy to grow in containers for your summer garden. You can also start the rhizomes indoors in late winter in order to give them a longer growing season and see earlier blooms. The plants go dormant after about 10 months of growing, so you can start them as early as 10 months from your usual first frost in fall.

Curcuma requires a wide container to make space for its rhizomes and may outgrow it quickly. Use at least a 5-gallon container (12 inches wide) or one that is more than double the length of the rhizome. For a 12-inch container, cut the rhizomes into 2 or 3-inch sections, making sure each has at least two or three eyes.

Use well-draining potting mix that includes plenty of organic matter. Fill the container most of the way with soil, then place the rhizome horizontally with the eyes facing up. Cover with 2 inches of potting mix and water well. Keep the soil lightly moist and place in a warm location that is at least 75° F. A heating mat can help warm the soil. Sprouts take as long as eight weeks to appear. Plants may be moved outdoors once days are warm and nighttime temperatures remain above 50° F. Gradually expose the plants to the outdoors, bringing them in during cold weather.

Potted curcuma requires more frequent watering, often daily during hot weather. If you have trouble keeping the plant hydrated, it's likely time to repot your curcuma in a new container with fresh potting mix. Once the plant goes dormant, you can remove the rhizomes and store them for replanting the next year.

Overwintering

If your soil freezes in winter, cover dormant plants with a couple of inches of mulch or straw to protect the rhizomes. Curcuma prefers to be on the drier side while it is dormant and generally doesn't require watering during this period.

To store rhizomes over the winter, dig up dormant plants and cut off stems with pruners. Brush off dirt and allow them to dry overnight. Store the rhizomes in sawdust or peat moss, and place in a cool (but not freezing), dark space until you are ready to replant.

If you are growing the turmeric plant, you can choose to harvest some of the rhizomes when the plant goes dormant. Wash off the soil and store in an open-air container in the refrigerator or in a cool, dry spot. Or, peel off the skins, dry the rhizomes, and grind into a powder.

Common Pests & Plant Diseases

Root rot can occur in overly wet soil. The most noticeable symptom is browning and death of leaves at the top of the plant. To determine if your plant is infected, dig it up and cut into a small section of the rhizome. Infected rhizomes have brown flesh with white specks. Cut off all infected parts of the rhizome, dust with sulfur powder, and replant in a new location.

Bacterial wilt occurs when soil temperatures rise, causing rapid wilting and then yellowing of leaves. The disease eventually plugs the stems, so plants must be removed and discarded. Leaf blotch and leaf spots can also happen when temperatures are high or leaves are overwatered. Prune and dispose of infected leaves.

If the soil is overly dry, spider mites may attack, but a mild insecticidal soap treats these pests. Young leaves are also susceptible to slugs and snails.

How To Get Curcuma To Bloom

Curcuma bloom in summer through fall and produce vibrant, cone-like flower bracts in various hues, including pink, purple, and white. Some species may start blooming later than others, and cool weather may delay it. Keeping curcuma in moist, well-draining soil helps increase the length of its bloom season. Even in summer, dry soil can cause the plants to go dormant. Dividing plants when they are too small may delay blooming by a year. Curcuma is a heavy feeder, so try fertilizing if you are not seeing flower spikes well into summer.

Common Problems With Curcuma

Curcuma primarily experiences fungi and disease when the water balance is not maintained. Here are some common issues:

Brown Leaf Tips

If leaves develop dry, crunchy tips or edges, this usually indicates too much sun, under-watering, or both. Curcuma must have consistent moisture during the growing season when planted in full sun. Increase watering or move it to a location that protects the plant from afternoon sun.

Leaves Turning Brown

If curcuma leaves turn brown, this doesn't mean your plant is dead, but it is a sign that it is entering dormancy, which occurs at the end of the blooming season during cool temperatures. Early leaf browning in summer happens if your soil is too dry, so water the plant at least once a week if you haven't had adequate rainfall.