1. Select peninsula benches to segregate different varieties.
Conventional, lengthwise benches typically cover about 60 percent of the floor area. (These run the length of the greenhouse.) The remaining 40 percent is for aisles, which are used to access plants. Consider changing to a peninsula arrangement that places the benches perpendicular to the sidewall, with 18-inch work aisles between and one 3-foot to 6-foot main center aisle. This will increase the grow space by at least 10 percent.
Benches are usually placed about 30 inches above the floor—a convenient work height. A peninsula arrangement will also work for larger container-grown plants placed on the floor. This system provides easier access for moving plants with carts or conveyors.
2. Movable benches allow up to 90 percent of the floor area to be covered with plants.
Install all benches on pipe rollers and allow them to move side-to-side by up to 2 feet (the width needed for a proper work aisle). When a particular bench must be reached, other benches are pushed apart to create an access aisle. This means attached irrigation, heat and electrical wiring has to be flexible. Benches as long as 200 feet can be moved easily by turning a support roller (which allows the bench to move from one side to the other) with a crank.
3. Tray systems work best in large, open growing areas.
Trays up to 6 feet wide and 20 feet long can be loaded with potted plants in the work area, then transported by cart or conveyor to the growing area. The trays can be moved back to the work area for spacing, maintenance or harvesting. The roller conveyor system uses flat bottom trays that ride on trolley wheels or fixed casters attached to support rails. In a second type of system, the rollers are attached to each tray and ride on the pipe rails. A low-cost transport cart can be used to move the trays from the propagation area to the veg spaces, then to flower areas. An alternate manual system uses rails with attached plastic trolley wheels.
4. Benches should be designed for efficiency.
Bench width can be 5 feet to 6 feet for access from both sides (3 feet for access from one side). Bench tops should be 13-gauge galvanized expanded metal, 1.5-inches square galvanized or vinyl-coated steel mesh, or UV-protected molded plastic to provide a good service life. Corners and sides should be smooth for safety. Use adjustable legs for leveling and bracing for stability.