Versatile mist chambers, framed with aluminum and glass and having access from top and sides, permit culture of an extensive number of, and different types of, vegetative plant organs as well as seeds and plant pathogens. Pneumatic atomizing nozzles are staggered to permit division of the chamber, and the spray emitted can be regulated from each nozzle. The amount of water vapor emitted is regulated by changing the air pressure or siphon height. Gauge-monitored pressure regulators and solenoid valves control the air and spray system. Timing devices can be used to inject water vapor at desired intervals. Air passing through a condensation tube is recycled past cone heaters, providing temperature from ambient to 90 F, and a duct and baffle system provides uniformity of temperature throughout. A combination recorder and controller maintains the desired temperature.