with the need of improved communication between scientists in this field of research and people who utilize plants. The Commission for Urban Horticulture was established in 1982 which deals with plants grown in urban areas, management techniques, the functional use of these plants as well the shortcomings of the current lack of knowledge regarding this field. The establishment of such a commission is an important indicator that this topic has reached a level of international recognition. Economic benefits There are many different economic benefits from gardening from saving money purchasing food and even on the utility bills. Developing countries can spend up to 60–80 percent of income on buying food alone. In Barbara Lake, Milfront Taciano and Gavin Michaels Journal of Psychology article "The Relative Influence of Psycho-Social Factors on Urban Gardening", they say that while people are saving money on buying food, having roof top gardens are also becoming popular. Having green roofs can reduce the cost of heating in the winter and help stay cool in the summer. Green roofs also can lower the cost of roof replacement. While green roofs are an addition to urban horticulture people are eating healthy while also improving the value of their property. Other benefits include increased employment from non-commercial jobs where producers include reductions on the cost of food. Production practices Crops are grown in flowerpots, growbags, small gardens or larger fields, using traditional or high-tech and innovative practices. Some new techniques that have been adapted to the urban situation and tackle the main city restrictions are also documented. These include horticultural production on built-up land using various types of substrates (e.g. roof top, organic production and hydroponic/aeroponic production). Because of this, it is also known as roof-top vegetable gardening/horticulture and container vegetable gardening/horticulture. Urban and peri-urban horticulture in Africa A report of the United Nations Food and Agriculture Organization, Growing greener cities in Africa, states that market gardening – i.e. irrigated, commercial production of fruit and vegetables in areas designated for the purpose, or in other urban open spaces – is the single most important source of locally grown, fresh produce in 10 out of 27 African countries for which data are available. Market gardening produces most of all the leafy vegetables consumed in Accra, Dakar, Bangui, Brazzaville, Ibadan, Kinshasa and Yaoundé, cities that, between them, have a total population of 22.5 million. Market gardens provide around half of the