Forcing as a horticultural technique has been recorded as early as 1608. Historically, rotting manure was used to create hotbeds which would provide warmer temperatures, allowing some or all of a farmer or gardener's crop to ripen earlier than it would in the open air. Cold frames and greenhouses are also methods of warming plants in order to force them. Greenhouses that were used specifically for growing off-season plants were sometimes known as forcing houses.
