Vegetables are a required source of vitamins, proteins, essential nutrients and carbohydrates for a balanced diet. In the mid-hill region in Nepal, farmers are limited to grow seasonal vegetables and are dependent on marketing mechanism of demand and supply. Growing off-season vegetables and fruits means improving the diet and increasing the household income.
Temperature fluctuations during summer make the vegetable crop susceptible to insects, pests and diseases and similarly, cold temperature during winter create favorable conditions for diseases. The tunnels offer protection to vegetables crops both in summer and in winter. The tunnel farming offers maximum crop yields, better maintenance of the fertility of land, controlled temperature and humidity, protection from wild animals and insects and better water conservation.
In order to produce vegetables under protection, it is necessary to consider a wind-free area, but if this is not possible, windbreaks should be erected or planted. Water must not be very saline, as it is further enriched by the addition of fertilizers. Finally, the tunnel must preferably be situated close to a market, in order to facilitate that products reach the market place as soon as possible. Crops such as cucumber, capsicum, tomato, pepper, bitter gourds, melons, brinjal and water melon are highly valued vegetables that show significant increase in yield when grown in tunnel farming.