Tech Solutions: Finding more room

One excellent way to reduce production cost per plant is to make better use of greenhouse space. The cost of providing the right environment is the same whether you are utilizing 50 percent of the space or if every square foot is covered with plants. Every square foot that has plants means additional dollars of income. The following are ways in which production can be increased. Some may require modification to the system you are now using; others are just common sense ways that we tend to overlook at times.

Peninsula benches
Conventional, lengthwise benches typically cover about 60 percent of the floor area. The remaining 40 percent is for aisles to access the plants. Changing to a peninsula arrangement that places the benches perpendicular to the sidewall – with 18-inch work aisles between and one 3-foot to 5-foot main aisle down the center – will increase growing space by at least 10 percent. This system also provides easier access for moving plants with carts or conveyors.

Movable benches
With this method, up to 90 percent of the total greenhouse area can be covered with benches. Two types of systems are common. The simplest is to install the benches that remain in the greenhouse but move sideways on rollers placed over a support frame. By moving the benches, a single work aisle can be located wherever it is needed. The steel rollers create very little friction and a 200-foot bench can usually be pushed by hand. Frequently, existing benches can be converted to movable ones to save on cost.

A more efficient system from a labor standpoint is the movable tray system. Modular trays, usually 6 feet wide by 8 feet to 20 feet long, are moved to and from the growing area on rails, carts or conveyors. Transplanting, loading and unloading trays are done in a headhouse area where everything is more convenient.
 

Roll-out benches
You can double growing space by placing one layer of plants on a heated floor and a second layer 20 to 30 inches above the floor on a pipe support system. During the day the trays are rolled outside the greenhouse onto a matching pipe network. Both crops receive full sunlight. At night, they are rolled back into the greenhouse. This system can be adapted to both hoophouses and gutter-connected ranges. The system is good for hardening off bedding plants during the spring and for potted plant production during the fall.
 

Floor production
It is a common practice to leave only one narrow aisle down the center of the greenhouse. Space utilization is almost 100 percent. This low-cost system can be improved with heated floors and boom watering. Access is only needed to observe the plants. When shipping time arrives, a work aisle can be created by removing the plants out of the center of the greenhouse first.
 

Flooded floors
A modification to the above system being adopted by the larger growers is the flooded floor system. Although costing more for the concrete floors, pumps, tanks and controls, plant production is very uniform due to the even watering. Handling of the plants is best accomplished with a gantry that straddles the width of the bay or with an adjustable finger fork truck.
 

Racks
If you are growing hanging baskets or larger potted plants, an A-frame rack system can double your growing space. Racks are especially effective where foliage plants are grown, creating conditions similar to a forest canopy. They can be built with 2 by 4 lumber and fence pipe or with heavy steel rods. Racks can be made movable but are usually fixed to the floor or overhead trusses. If you are going to suspend the racks, be sure that the greenhouse frame is strong enough.
 

Hanging baskets
Many growers place containers over part of their growing area to increase space utilization. In taller greenhouses, two or three tiers of baskets may be suspended. These baskets are fitted with an automatic watering system and the spacing depends on the light requirements of the crop on the floor or benches beneath.

A more efficient system is the hanging basket conveyor which is attached to the overhead trusses in the greenhouse. Plants spaced as close as 8 inches apart are supported by a conveyor that moves them past work and watering stations. The savings in labor of having plants brought to an aisle for placement, inspection and shipping can offset the cost of the system.

Under bench production
A few growers utilize the space under benches as a production area. It works well for crops such as ground cover. By adding about 25 watts of fluorescent light per square foot, other low light crops can be grown. Watering is more difficult and there could be increased disease problems.
 

Utilize aisles and walkways
I have been in many greenhouses where wide aisles were installed to allow for customers during the busy retail sales period. In gutter-connected houses, these are sometimes 10 to 12 feet wide. This wide an aisle is seldom needed except during shipping time and some of this space could be filled with plants, either on the floor, benches or racks.
 

Movable greenhouses
A trend by growers using high tunnels for vegetable production is installing low-cost movable greenhouses. One area is used for early season production of greens. When the weather warms up, the greenhouse is moved to the adjacent area for warm season crops such as tomatoes and cucumbers. The greenhouse frame runs on rails or skids and is moved with a tractor or winches. These structures may also have application for protection of perennial and herb plants during the winter and for cool temperature production during the spring and fall. The area between the two locations could be set up to house a heater and water supply.
 

Removable greenhouses
The space allowed for snow accumulation between free-standing greenhouses could be set up with hoops that are covered with plastic after the treat of snow is over. This space is the most valuable during late spring, just before shipping season begins when the conventional greenhouse space is overflowing and there is a need to harden off plants. A little heat could be added, maybe from the adjacent greenhouse.

As energy costs increase, good growing space utilization is important. Making use of some of the above systems, keeping growing space full and providing optimum environment control can help to produce plants at the lowest cost.