The choice of a ventilation system for a tobacco greenhouse is possibly the most important choice. This choice determines how often the greenhouse operator must visit the greenhouse each day. Systems can be active (mechanical and use energy, fans and louvers) or passive (natural ventilation, no energy use, sidewalls). The systems can be automatic (controlled by thermostats) or manual (controlled by the greenhouse operator).
Standard, conventional greenhouses have active, automatic ventilation systems. These systems are marginally more expensive to purchase. Plus these systems are more complicated and somewhat more expensive to install. However, these systems are reliable and require only casual maintenance and adjustment. The major advantage to these systems is that they give excellent temperature control in the greenhouse.
Typical tobacco greenhouses have a mixed ventilation system. Active, automatic system for the first stage of ventilation and a passive or natural, manual system for the second stage of ventilation. This system is somewhat less expensive than a total fan ventilated greenhouse plus they are easier to install. However, these systems REQUIRE that the greenhouse operator visit the greenhouse a number of times during the day OR that greenhouse temperature control will be less than optimal.
RECOMMENDATIONS:
1. The best automated greenhouse system for tobacco plants is a ventilation system that uses fans and louvers for all ventilation. So if a farmer cannot be available at the greenhouse 3 to 10 times each day (while plants are in the greenhouse), then an automated ventilation system with fans and louvers is the choice.
2. If a tobacco transplant grower will be available every day (and possibly every 1-2 hours during the day)that the plants are in the greenhouse, a manual, passive ventilation system should produce appropriate temperature control for the production of high quality transplants.
3. Every tobacco farmer must consider outdoor beds at the same time that they consider a greenhouse. They offer the lowest cost and possibly the least management to produce quality transplants. Yet, numerous farmers have become tired of the hassle of pulling plastic off and on an outdoor bed and feel the investment in a greenhouse will make plant production easier.
4. We would like to know of farmers that use an automatic, passive (or natural) ventilation system to learn more about its advantages and disadvantages for their operations.