Bioreactors are mechanical in vitro systems that allow optimal air, water and solutes availability. Shoot systems developed during micropropagation usually require stationary gaseous phase to grow normally. Intermittent immersion of plantlets in liquid medium, by varied mechanical designs, produced superior growth, when compared to agar-gelled systems. We presented data from our laboratory to demonstrate reasons why plantlets in liquid grow faster and larger than agar that included: 1) greater water availability, 2) greater solute transfer within the medium, 3) larger surface areas for solutes transfer from medium to plantlet, and 4) the ability to use higher solute concentrations due to greater water availability. Improved labor efficiency in micropropagation was also realized by faster, non-oriented transfer of plantlets during subculture and the ease of removing medium when planting out in greenhouse. Larger vessels of liquid allow plantlets to get larger, than with agar, and using growth retardants or high osmotic medium controls plantlet size and further increases system efficiency. In a single operation batch process, solutes such as sucrose or phosphorus, may not be in adequate amounts at the onset of a culture cycle to maintain prolonged growth. Supplementing medium during the culture cycle allow plantlets to attain more mature status, such as the formation of storage organs in geophytes. This review featured two bioreactors, the Liquid Lab Rocker and the Artificial Plant Ovary, that allow medium supplementation and multi-functional process development. For bioreactors to be successfully deployed, their cost needs to be offset by labor savings in transfer time and greater numbers of better developed plantlets that accrue more value in the market.