Urban cities are lacking strategies, processes and technologies to provide stable, healthy, and safe food for growing populations. Intensive organic farming is another tool in sustainable agriculture but requires the application of bulk quantity of organic inputs for nutrition and pest control,which adds to the cost of production and possible environmental pollution. In such a case, the vertical farming in megacities plays a crucial role in providing food and nutritional security with resource efficiency.The cultivation of such high value crops under different innovation techniques results in increased cost of production because of the necessity for controlled environmental conditions, continuous supply and recirculation of good quality irrigation water and nutrients, and post-harvest handling costs until the product reaches the consumer. This would automatically increase the market price of the produce, which cannot be afforded by people with low-in come.Thus, it is essential to design innovative vertical farming technologies, which lower production costs without sacrificing product quality.

Microgreens are utilized as a suitable crop since they are rich in phytonutrients and vitamins while not necessarily needing external application of fertilizers. Microgreens are tender immature greens of vegetables, herbs, and grains providing intense flavors, vivid colors, and tender textures. Microgreens currently fetch a high price in the market because of its rich nutrition content and post harvest practices,such that the people with low income level cannot afford to buy them for enhancing their nutrition by adding them in their regular diet. This review is concerned about the production of highly nutritious and safe food with minimal post-harvest wastage by reducing the cost of production using containerized vertical farming technology. Vertical farming facilitates the production of high value crops with higher yield than obtained from conventional farming by efficient utilization of resources such as water, nutrients, space and time, thereby, reducing carbon footprint . This innovation utilizes both the horizontal and vertical spaces more effectively, thereby, producing higher yield per unit volume under controlled environmental conditions of temperature, light,carbon dioxide and humidity. There are different types of vertical farming innovations like hydroponics, aeroponics, and aquaponics where the nutrients are effectively utilized and monitored for physical and chemical parameters like quality, pH, and solubility in water.

Since vertical farming is experimented within a closed and controlled environment, sunlight as a source of light for carrying out photosynthesis is replaced by artificial lights with different spectra and intensities. In such a case, LED lights are more effective with high energy use efficiency and durability than traditional light sources like fluorescent lamps. Commercial hydroponics is a modern technology involving plant growth in nutrient solution without the use of soil as a rooting medium. This system involves the application of inorganic nutrients through irrigation water and recirculation of nutrient solution thereby avoiding wastage by leaching. The main advantages of this system include mitigation of problems related to soil such assoil-borne diseases, poor physical and chemical properties with decreased application of plant protection chemicals. Hydroponics results in enhancement of quality of fruits and flowers with precise application of nutrients. The disadvantages of hydroponics are higher installation cost for the soilless culture system,investment cost and technical skills needed to manage with them to obtain maximum yield and product quality within controlled environmental growing conditions.

Aeroponics represents the production of crops under air or mist environment without the use of soil as the rooting medium. In this system, the roots of the plants are exposed to the environment and can grow freely. The advantage of this system is that, it uses only 10% of the water needed for hydroponics and aquaponics because of the use of mist and hence the roots can access much more oxygen than in hydroponics and aquaponics. The disadvantages of this system are that a failure in the system would stop the flow of nutrient solution in the form of mist and may lead to the death of the crop . Aquaponics is a system which combines both hydroponics to produce crops and aquaculture to cultivate fish. The advantage of this system is that the fecal matter of fish would naturally become the organic fertiliser for the crops. This would eliminate the necessity for the solid waste disposal which would impose high management cost.