Indoor gardening is being investigated with the goal of having a constant supply of herbs and vegetables for culinary use. Many practical recipes (especially, to our knowledge, in Vietnamese cuisine) require fresh herbs which are not available frozen. Purchasing fresh herbs to make these recipes is non-ideal due to the inconvenience of visiting a vendor, as well as due to the combined cost and short shelf-life of these ingredients. We opt instead to produce the crops ourselves, ameliorating the pragmatic difficulties associated with the aforementioned recipes. This endeavor is further motivated by recent research which suggests a positive correlation between the presence of living, well-maintained plant life and morale in the laboratory . The particular species we intend to grow and harvest are known by their common names cilantro (coriander), Thai basil, garlic chives (jiu cai), Chinese broccoli (gai lan), holy basil (tulsi), basil, and spinach. Other species, such as bok choy, spearmint and Japanese mustard greens (komatsuna) may be investigated, conditional upon demand among researchers, availability of seeds, and availability of space in the indoor garden.
Bubble-based hydroponics has been chosen as the method to be used to grow the plants. This is due to the simultaneous simplicity and portability of the system, the latter due to the ability to simply drain the water reservoir prior to relocating the garden. Traditional dirt-based gardening does not offer this convenience. Bubble-based hydroponics involves using a bubble source to circulate a nutrient solution throughout a reservoir, as well as to aerate the solution. Plants are placed in mesh pots which come in contact with the water surface. A metal-hydride light is used to provide light of intensity similar to that of natural sunlight.
Prior to placement in the hydroponic system, seeds must be germinated in a rockwool seeding medium. The items needed to prepare this process are shown in Figure 1.
Figure 1. Seeds, rockwool seeding medium, pH-adjusted nutrient solution, pH modifiers, and germination vessels are shown here. The rockwool is saturated in the solution, seeds are added, and then the rockwool pieces are placed in the germination vessels.
In order to partially neutralize the residual alkalinity of the rockwool seeding medium and to provide nutrients to the seeds, a nutrient solution is prepared and adjusted to a pH of 5.5 using citric acid and sodium bicarbonate. The rockwool seeding medium is saturated in this solution. Seeds are then placed in the seeding medium, taking care to record which seeds where placed in which holes in the medium. Finally the pieces of rockwool are placed in labelled germination vessels, which are kept partially sealed in order to preserve moisture. Figure 2 shows the occupied germination vessels. Light for the sprouting plants is provided by an overhead bulb, and heat by a cryptocurrency mining computer.
Figure 2. The filled germination vessels have been placed in a relatively warm and well-lit location to promote germination.
In order to prepare to plant the sprouted seeds in the hydroponic system, a basic indoor gardening laboratory is set up as shown in Figure 3. A metal-hydride bulb and reflector are suspended from the ceiling. When the light source turned on to full power, an illuminance of 20,000 +/- 10% lux is measured at a distance of 20 cm from the growth reservoir; this is sufficient to replicate realistic outdoor lighting conditions. A darkened curtain is suspended from the ceiling to protect people entering the laboratory from the bright light. The growth reservoir is painted black to inhibit algal growth within the reservoir.
Figure 3. This is a basic hydroponic indoor gardening laboratory, with a black reservoir to contain the nutrient solution and a metal-halide bulb and reflector to provide light to the plants.
Research updates with continue when the plants have sprouted and are ready for transfer to the hydroponic system.