Also try to get the largest healthiest looking ones available. Larger turmeric roots will have multiple branches and shoots which can be separated and planted to start multiple plants.
Once you've procured turmeric roots or rhizomes simply plant them in a loose potting soil preferably amended with vermiculite. Any knots, knobs and buds on the root or rhizome should be planted facing upwards. It is best to start them in a suitable container, unless you are fortunate enough to reside a very warm temperate zone in which case they can be started directly in the ground. Transplants for outdoor growing should be transplanted in late Autumn and once again that is in warm temperate climates only. Most other will be growing in containers and transporting in and out doors periodically.
Light Shade is best, avoid full sun particularly in warm sunny areas and also avoid full shade. It does best in light shade.
Water lightly daily, Turmeric requires moisture, but don't over saturate the soil, just keep it moist. It will not tolerant being water logged and root rot is not uncommon. Grown in the wild or outdoors, the plant will prosper in clay and marsh - but the roots- which is what you are growing it for will be next to useless. During the winter cut back on the water.
Fertilizer is not absolutely essential so long as you began with rich fertikle soil, but modest amounts are helpful in producing the best possible crop. Do not over fertilize, fertilize lightly and infrequently or you could damage the roots and or plant. If you notice a premature yellowing of the leaves or burnt tips chances are you over fertilized.
Phosphorus and potassium support root growth, fertilizers high in phosphorus and potassium are especially helpful in root crops, which Turmeric is, during the active growing season. Phosphorus also promotes flower production which won't help your root development or hurt it, flowering or 'bolting' will not effect the turmeric root. Use Nitrogen in moderation, as it will promote lush foliage at the expense of the rest of the plant. A fertilizer with an N-P-K ratio where the first number [N] is fairly low while the last two [P-K] are higher is best. See - Understanding Fertilizer labels.
Growing turmeric indoors in pots for most people is the best option. They aren't gonna go good with African violets or similar house plants but they will go well next to a banana plant - they reach about 4 feet tall when fully mature.
Pests are rarely an issue with this plant, but aphids, mites and white flies will suck on any vegetation. White flies are more common in greenhouse or other indoor scenarios.
Fungal infections are also not very common, although not unheard of. Keep an eye out for brownish patches on the foliage or yellowing of leaves as these are symptoms of several fungal infections, but particularly leaf blotch which is somewhat treatable.
If you do notice a yellowing of the leaves, it is not necessarily a disease. As the plant approaches the end of its seasonal cycle [8 - 10 Months] this will happen naturally. The leaves will also dry out somewhat. This is an indication that it is time to harvest the tubers.
Dig up the plant, remove the rhizomes from the stems and you have harvested your Turmeric root. Store unpeeled roots in an air-tight container in a cool dark place for up to 6 months. Fresh turmeric or even stored turmeric is much more potent than anything you may be accustomed to from your local grocer. A little bit will go a long way.
Turmeric Omelettes Grow Ginseng Parsnips Jerusalem Artichoke