FLOOR HEATING OF GREENHOUSES
Bedding plant operators have traditionally grown in plastic film greenhouses and on the floor to eliminate the cost of benches. A common problem has been the cold soil temperature. Neither warm air nor hot water heating systems are able to maintain warm soil temperatures without operating the greenhouse at ambient temperatures higher than necessary.
The use of porous concrete (that is, concrete made with only cement and aggregate, without sand) has become popular for greenhouse floors. Porous concrete provides a solid surface and controls weeds, yet allows excess irrigation water to drain through. This type of floor allows for the placement of pipe in the floor and creates a radiant heating system for the greenhouse, similar to what has been used in home and industry for many years. Regular concrete has had limited acceptance because it is impervious to drainage and causes crop damage in low areas which collect water.