Chapter 3
Greenhouse benches provide basic convenience in the production of crops. The use of greenhouse benches has several advantages over planting directly in the greenhouse soil or setting pots on the greenhouse floor: (1) plants are at a more convenient height to work comfortably; (2) benches permit a more effective display of plants; (3) benches provide improved air circulation and environmental control around the plants; and (4) benches permit better disease and growth control.
Benching materials should allow for air circulation around the plants and drainage from the containers. This is to minimize disease problems and to allow for complete coverage by fumigant and fogged pesticides. Common bench surface materials are: red wood lath in woven wire, red wood boards with ¼ to ½ inch spaces, l-inch square 14-gauge welded-wire fabric, and expanded steel mesh.
Two basic designs exist for the arrangement of benches in the greenhouse: longitudinal and peninsular. Longitudinal design results in the arrangement of benches in a linear fashion, with all benches and aisles running the same direction in the greenhouse (See Figure 3.2). This permits long continuous runs of watering lines, heating pipes, and/or plant support techniques. Peninsular design utilizes a large main aisle with benches running perpendicular to the main aisle, with smaller aisles between these benches (See Figure 3.3).
These strong, durable benches remain in one place (See Figure 3.1). The main reason to use this type of bench is to provide additional aisle space when more access to the plants is needed. Stationary benches are common in retail, educational, and research growing operations.
Rolling benches are built in the same fashion as stationary benches, except the bench tops are supported on pipe rollers and allowed to move sideways (See Figure 3.4). Bench platforms are moved by a crank at the end of the bench from side to side.
Container benches (also called movable benches, pallet benches, or Dutch trays) offer complete handling of plant material from planting to shipping. By using a container bench system a grower can easily move the crops between different climate zones. Some growers move the benches in and out of coolers where plants are vernalized (given a period of cold so they'll initiate flowers). With mobile trays the potted plants are set on a large tray, typically 4 to 6 feet wide and 8 to14 feet long, instead of on a bench (See Figure 3.5). The tray system saves considerable labor as the plants don't have to be carried to a cart or conveyor. Two types of tray transport systems are common. The roller conveyor system uses flat bottom trays that ride on trolley wheels or fixed casters attached to support rails.
Ebb-and-flood benches typically consist of a metal frame that can be leveled with a water-tight liner or water-tight movable trays to contain the nutrient solution (See Figure 3.6). Channels in the bottom of the bench allow the water to distribute evenly and to drain rapidly when the water supply is shut off. This allows the bench top to dry reducing algae growth and disease potential. In operation nutrient solution is pumped from a holding tank to a level of ¾ to 1 inch depth in the bench and held there for 10 minutes or long enough for the media in the container to absorb the solution.
Trough benches typically consist of a metal frame that supports a series of troughs running lengthwise across the bench (See Figure 3.7). The troughs are usually made of aluminum or polystyrene plastic. Unlike an ebb-and-flood bench system, which is perfectly level, trough systems arc usually sloped slightly from one end to the other.
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