Vertical Gardens

Vertical gardening aims to advance the productivity levels of urban and sub-urban agricultural production sites where most often available space is the biggest agricultural limitation. Plenty of different design solutions are available. The design of vertical garden (sometimes also called green walls) depends on the available material, space and local preferences as well as on the creativity and imagination of the users. Crops that can be grown comprise food crops (vegetables, fruits, herbs) and non-food crops (e.g. ornamental plants, medical plants). As a growing media soil, compost, vermicompost, terra preta compost, acrylic material as well as aquaponic and aeroponic solutions can be used. The crops can be grown in sacks, bags, flowerpots and all kinds of available receptacles like bins, cans, tins, bottles, tanks or boxes. They can be placed on yet unused places like on the roof of houses, balconies, on the top of walls or just hung up. Where space is available, earth beds of larger surface may even be installed, but require some expert design to control water drainage and infiltration.

Further vertical garden solutions that allow for a good utilisation of available space are cultivation arches, greywater towers or cultivation bags (see pictures below).

Other systems like cultivation umbrellas, cultivation bangles or some kind of cultivation that have also been proven useful (see picture below). 

A variety of different substructures like cultivation ladders, pyramids or racks can be designed and constructed to grow plants vertically (see pictures below).

Walls, murals and exterior walls of houses are also often used as a vertical gardening alternative either just as beautification of the wall or to grow vegetables and other crops along the wall. Vertical gardens also have a positive effect on the house climate (keeping the walls cool in summer). Walls can be used easily without big additional construction work. Either the wall will be modified with additional bricks or holders can be used for growing plants on the surface of the wall (see pictures below). In Botswana for instance, Gus Nilsson, a Swedish horticulturist has developed a system of intensive horticulture for dry tropical areas, based on walls with built-in containers (WINBLAD / SIMPSON-HERBERT 2004). Plants should be selected according to the orientation of the wall. Walls directed North will have different characteristics with regard to exposure to the sun, wind and rain then those directed South.

To make sure plants do grow well on vertical surfaces regular water and nutrient supply needs to be ensured. Irrigation techniques like bottle irrigation (see also irrigation) or regular watering with watering cans and alike can be used. Essential plant nutrients like Nitrogen, Phosphorus and Potassium should be applied according to the needs of the plants and in similar amounts as removed from the growing medium with the harvest. A good solution to do this is by making use of compost, vermicompost, terra preta compost and/or human urine or other organic fertiliser sources (see also chapters on urine use small- and large-scale, use of compost). The use of treated or partly treated greywater and reclaimed water can also be a cost effective alternative water and nutrient source, particularly in water scarce areas.