Vertical Crop Production in Cities

Vertical growing is not restricted to the walls and facades of buildings.  In fact, greenhouse growers have long made use of what space they have available inside their protective glass structures to harvest the most amount of produce possible.  In taller structures methods for growing upwards, such as shelving and stacking systems, and the use of A-frames have evolved.

There is always a way to cultivate food plants as long as you have a structure to grow them up in. The stability of the vertical growth structure and environmental factors are frequently the only restrictions for outdoor crops. 

Climbers on trellis, arches and upright grow frames

Although protected structures help control environmental factors in many vertical food growing systems, there are other options for outdoor food production. In recent years, for example, there has been a trend toward inner-city restaurants growing their own crops from gardens for use in dishes. Because of the limited space at the back of restaurants, many of these 'kitchen gardens' are vertical garden setups.

A green wall for edible plant growing can be as simple as a series of pots or planting pockets mounted on a frame, which is a low-cost and simple way to construct a green wall. Another option is to lean an old wooden pallet against a wall and place pots on the cross beams. Dwarf and compact varieties of herbs and vegetables, such as marjoram, thyme, and basil, can be grown in this manner. Edible flowers such as nasturtium, chamomile, daisies, and pansies can also be included and used as garnishes. It's a good idea to have climbing plants like beans and peas near the top of vertical food gardens like these so they can grow.

A vertical herb or vegetable garden may also make use of a fence, wall, trellis, or lattice system. Many years ago we used vertical space to accommodate edible plants, such as passionfruit on trellis, grapes on pergolas and trellis, espaliered fruit trees on fences or against walls, climbing frames for beans, peas, Chinese gooseberries, and other creeping plants with roots in the soil or containers at ground level.

There are, of course, numerous other approaches to developing outdoor food production systems, with space and resources frequently being the only constraints. A vertical tower, for example, can be constructed using wire mesh such as chicken wire bent into a tube and cut to the desired height. The inside of the tube can be lined with black plastic or felt before being filled with a suitable growing medium, allowing for a taller tower while remaining lightweight. After moistening the media, seedling vegetables such as salad plants are inserted through holes in the lining. Plant towers like these can be attached to existing structures with wire braces. The advantage of wire mesh is that its versatility allows for the use of various shaped vertical containers.

 Another option is to secure lengths of guttering to the walls with U-brackets. These can be separated into tiers. Drainage holes are drilled along the length of each length of guttering. They are then filled with the appropriate potting mix and various herbs and vegetables are grown inside.

Hanging baskets and window boxes can help to increase vertical outdoor food production. Strawberries, cherry tomatoes, peas, and lettuce are all good choices for baskets. Window boxes and planters on walls and balconies allow for the growth of a wide variety of herbs as well as vegetables such as sweet potatoes, radishes, and onions due to the increased root space.

The disadvantage of such exposed systems is that the potting medium dries out quickly, so it is always best to use a high-quality potting mix. Unless these gardens use a simple automated irrigation system, such as drippers, it may be necessary to hand water the plants several times per day in warm to hot weather. Because the pots or pockets are small, nutrients leach out quickly. If the garden is not constantly monitored for moisture, the media becomes hydrophobic (rejects moisture). Soil wetting agents and surface mulches are two methods for combating moisture loss. 

Edibles are occasionally incorporated into prefabricated sheet and mat freestanding walls. Herbs and lettuce work well in these scenarios because leaves can be picked off as needed without having to harvest the entire plant. In addition to exterior walls, some green walls inside hotels and restaurants use crops in this manner. An irrigation system will benefit any system that exceeds a comfortable height for hand watering, whether with a watering can or an extendable lance. Going too high, on the other hand, makes crop harvesting more difficult and may necessitate the use of scaffolding or ladders.

Of course, there are many more complex systems that could be used for herb, vegetable and fruit growing on a vertical garden or a grow wall, rather than just the simple ones described here. These go up to fully automated crop production systems large and small. 

 

 

Some more sophisticated examples of different ways to produce food crops vertically include:

·       Hydroponics - Any method of growing plants without the use of soil. Roots of plants are suspended in a sterile medium and the plants are fed by means of water containing nutrients. The Nutrient Film Technique (NFT) is a method of soilless culture where plants are grown bare rooted in long narrow channels which enclose a shallow stream of nutrient solution. The nutrient solution flows continuously through the channel and is recycled from the bottom to the top end by a pump. This method suits crops such as lettuce, herbs and salad greens which have smaller root systems.

·       Aquaponics - A specialised form of hydroponics which incorporates fish or crustaceans into a hydroponics page system. Consequently, the end product of a productive aquaponics system is both food crops and fish to eat. Unlike hydroponics where nutrient solutions are provided to plants to help them grow, in aquaponics the plants are fed via the effluent from the fish. 

·       Mushroom trays on shelves - Different types of buildings can be adapted for growing mushrooms and these include anything from garden sheds to basements or disused warehouses.

·       Greenhouses with 2 or 3 planting shelves, each with artificial lighting

·       Layered troughs

·       Containers on a vertical conveyor

·       Multi-storey buildings with artificially lit and environmentally controlled growing rooms on each level

All of the above may require some technical expertise to set up and master the optimum environment in terms of e.g. temperature, humidity, light intensities etc.