Konjac

Konjac (Amorphophallus konjac) is a shade-demanding, corm-forming perennial aroid grown for the glucomannan stored in its underground corm. Unlike leafy or fruiting crops it is a multi-year crop: each spring a dormant corm sends up a single umbrella-like leaf that feeds the swelling corm through summer, then lodges into winter dormancy, and the corm is lifted, graded, and replanted for two to four seasons until it reaches market size. It wants 50-70% shade, warm humid conditions (20-30C, 70-90% RH), a deep free-draining substrate, and a potassium-forward feed that rises through corm bulking. Konjac is highly prone to bacterial soft rot, and the raw corm is a calcium-oxalate irritant that must be processed before it is safe to eat.