tan heat noun2 •heat generated by the fermentation of tan bark waste; generally used in horticulture as a source of bottom heat for potted plants in greenhouses; the application of tan heat to greenhouse plants, mainly during the 18-19th century.Being a native of the West Indies, [Bignonia leucoxylon] does not flourish without the assistance of tan heat; but will live in any situation of the hothouse... — 1797 •a bed of tan bark waste used as a source of mild bottom heat for potted plants in greenhouses or hothouses.
