Is stevia farming a good idea in India and what about the market?

Stevia is a natural sweetener crop with genuine demand from the food, pharma and sugar free product industry, but you must approach it carefully because the market is buyer driven, not open mandi. It is a perennial grown from planting material, established on well drained soil, and you harvest leaves repeatedly several times a year for a few years, drying them for sale. The real risk is selling, since dried leaf is bought by specific processors and companies, often on contract, and farmers who planted on speculation without a buyer have struggled. So treat a firm buyback or processing tie up as essential before planting, and be cautious of agents promising guaranteed high returns and selling overpriced saplings. Yield builds after the first year. Done with a real buyer it can be a steady niche crop. Confirm a buyer, realistic dried leaf rates and quality specs in writing before investing.