The much publicised health benefits of turmeric, including anti-inflammatory and antioxidant properties, have made it a popular addition to everything from lattes to smoothies to teas. Although fresh turmeric tubers have been said to have more potent health benefits than the powdered turmeric sold in grocery stores, a small bag of them can cost upwards of $20. If that sounds too expensive for your budget, there’s good news for greenhouse owners because they can easily grow turmeric even in northern climates. It takes a while, however, roughly seven to nine months, depending on the greenhouse temperature. Turmeric, remember, is a tropical plant that does best at around 75˚ to 80˚F. The lower the temperature, the longer turmeric cultivation takes.
To grow turmeric, start by carefully slicing a turmeric tuber to allocate one eye per slice. Then place each slice in moist, pH-neutral potting soil using shallow, 8” to 12” pots to give the tuber pieces space to spread as they grow. (A coir-based potting soil is said to be ideal for Turmeric although mine seem to grow well in soil with left-over peat based potting soil mixed in.) Alternatively, you can initially put the potting soil in zippered plastic bags and start the tuber slices there, transferring them to pots after they have sprouted and leaf growth has begun.
Here in New England, I start my turmeric tubers in late December or early January under germination-chamber LED lights that are kept on up to 14 hours a day. A heat mat maintains the temperature at around 65˚ to 70˚F. The turmeric pots remain in this chamber until April when they go into my greenhouse. At this time, the plants usually have a shoot about 6” to 12” tall. Sometimes I let the plants continue to grow in their pots for a while, but as soon as I have space, I set them into a greenhouse growing bed. Here they’ll grow to about 3’ in height and produce large, spade-shaped leaves.
I water my turmeric plants every few days to help the tubers develop. I’ve heard of watering them with compost tea or manure tea, but I’ve used organic seaweed tea instead, seaweed being plentiful where I live in coastal Rhode Island. Such teas aren’t essential, however. The same fertilizer used for most other root crops will also work for turmeric.
When the tops of the turmeric plants die back (often when temperatures drop in the fall), it’s usually time to harvest. Simply dig the tubers out of the ground, wash them off and use them. But remember to keep a few tubers for next season.