Mysteries of Curcuma Phaeocaulis: A Guide to Black Turmeric

Curcuma phaeocaulis, also known as Black Turmeric or Wild Turmeric, is a perennial herbaceous plant in the ginger family. Its flower stalk emerges directly from the rhizome, usually before the leaves, extending 10-20 cm in length and covered in several loose, slender, scale-like sheaths.

The spike-shaped inflorescences are broad-oval in shape, 10-18 cm long, and 5-8 cm wide. The bracts are ovate to inverted ovate, slightly spreading, blunt at the tip, green at the base, red at the tip, and longer and purple at the top.

The calyx is 1-1.2 cm long, white, and trifurcated at the tip. The corolla tube is 2-2.5 cm long, the lobes are oblong, yellow, uneven, with the one at the back being larger, 1.5-2 cm long, and having a small pointed tip.

The plant blooms from April to June and can be found from India to Malaysia. The rhizome, called “Ezhu,” is used in medicine to treat blood stasis, abdominal pain, masses, indigestion, menstrual blockage due to blood stasis, and pain from falls and injuries.

The tuber is called “Green Silk Yujin” and is used to promote qi, relieve depression, break up blood stasis, and alleviate pain.

I. Physical Features

The plant stands about 1 meter tall; the rhizome is cylindrical, fleshy, with a camphor-like aroma, and is light yellow or white. The roots are slender or swell into a tuber at the end.

The leaves stand upright, are elliptic-oblong to lanceolate-oblong, 25-35 (60) cm long, 10-15 cm wide, often with purple spots in the middle, and are hairless; the petiole is longer than the leaf blade.

The flower stalk emerges directly from the rhizome, usually before the leaves, extending 10-20 cm in length and covered in several loose, slender, scale-like sheaths. The spike-shaped inflorescences are broad-oval in shape, 10-18 cm long, and 5-8 cm wide.

The bracts are ovate to inverted ovate, slightly spreading, blunt at the tip, green at the base, red at the tip, and longer and purple at the top. The calyx is 1-1.2 cm long, white, and trifurcated at the tip.

The corolla tube is 2-2.5 cm long, the lobes are oblong, yellow, uneven, with the one at the back being larger, 1.5-2 cm long, and having a small pointed tip.

The side-borne degenerate stamens are smaller than the labellum; the labellum is yellow, nearly inverted ovate, about 2 cm long, 1.2-1.5 cm wide, with a slightly missing tip.

The anther is about 4 mm long, with a bifurcated spur at the base of the anther septum. The ovary is hairless. The plant blooms from April to June.

II. Growing Environment

Cultivated under the shade of wild forests.

III. Distribution Range

This plant can be found from India to Malaysia.

IV. Main Value

The rhizome, known as “Zedoary,” is used for medicinal purposes. It is primarily used to treat “stagnation of qi and blood, abdominal pain, masses, accumulation, indigestion, women’s menstrual blockage due to blood stasis, and pain from falls and injuries.”

The tuber is known as “Green Silk Turmeric,” which has the function of promoting qi, relieving depression, breaking blood stasis, and relieving pain.

V. Growth & Propagation

Choosing the Rhizome: Choose robust and plump new rhizomes from the current year’s harvest for storage and seeding. Before planting, expose the seeds to the sun for 1-2 days, remove the root hairs, and separate them by size.

Cut the large ones into several pieces, each piece having 1-2 buds. After cutting, let them dry slightly to heal the wound, or coat the wound with wood ash.

Planting Period: The planting period varies depending on the variety and region. Warm turmeric (Zedoary) is suitable for planting in early to mid-April, while Zedoary is best planted in late May to June.

Planting Method: In a well-prepared ridge, dig holes at a row spacing of 30 cm × 20-25 cm, with a hole depth of 6-9 cm. Place one large rhizome or two small rhizomes in each hole, with the bud facing upward.

After planting, cover the soil to a depth of 6 cm and slightly compress it. About 100 kg of rhizomes per acre are used for seeding. To increase land efficiency, the main production areas often adopt intercropping methods with crops like corn and soybeans.

The corn and soybeans can be hole-sown at the end of March or the beginning of April in ridge trenches or on the ridge, with an appropriately increased row spacing.

In late June, Zedoary can be intercropped between the rows and plants of corn, with a row spacing of 33 cm. Dig a hole 7 cm deep, arranged in a triangular pattern, put 5 seeds in each hole, one at each corner and one in the center, with the bud facing upward.

Cover with fine soil or compost, requiring about 150 kg of rhizomes per acre. Warm turmeric (Zedoary) rhizomes are divided into six categories: old head, big head, two heads, three heads, nipple, and small nipple.

The old head is the rhizome that first sprouts from the mother plant; the big head is the rhizome that grows on the old head; the two heads grow on the big head; the three heads grow on the two heads; and the nipple and small nipple follow in sequence.

Except for the old head, which can’t be used as seed, the rest can be used. However, using the big head as seed is costly due to its large size, and the small nipple is weak in growth. Therefore, these two types are not used for seeding in production.

Generally, the two heads and three heads, which are robust, full of buds, and short and stout, are selected for seeding. The shorter the rhizome used for seeding, the better. Seeds should be sown around the Qingming Festival.

In narrow ridges, plant a single row with a plant spacing of 33 cm. For wide ridges, plant two rows in a triangular pattern with a plant and row spacing of 50 cm. The hole should be 17-20 cm wide and about 7-10 cm deep.

The bottom of the hole should be flat, avoid making it too deep and pointed as this disperses the tuber, making harvesting labour-intensive and difficult to clean completely.

Place one root bud in each hole, with the bud facing upward. Cover with 3-7 cm of soil. Use 125-150 kg of rhizomes per acre.