If flats are used for holding the rooted cuttings, the flats can be placed directly on the bench top or on sand. Since the mist tends to lower soil temperature which restricts root development, best results are obtained when the soil medium is warmed. For most plants, a temperature of 75 o F is considered optimum. To achieve such temperatures, electric heating cable can be placed on the bench or slightly above the gravel layer in the sand. Thermostat controls are also available which permit raising the soil temperature to whatever level is desired for the specific plant species being rooted.
Many growers place flats of cuttings or seeds directly on the bench.
This practice allows for greater sanitation since flats can be easily moved and the benches cleaned. When the greenhouse is heated with steam or hot water, some soil warming can also be provided by placing one or more heating pipes below the bench. If this arrangement is used, the piping below the bench should be separately controlled so that heat can be added even when greenhouse space heating is not required. Other features of benches such as required supporting framework, bench dimensions, and construction features are discussed in detail in OSU Extension Facts F-6703 Greenhouse Floors and Benches. Mist benches are often placed in inexpensive polyethylene quonsets in nurseries for added protection to the propagation area.