Support Systems
Since aeroponics is defined, in part, by a lack of growth media, the question of how to keep plants in place, roots down and leaves up, is pretty central. Roots need to be suspended, freely exposed to air and mist on all sides. Leaves need to be similarly unencumbered, to promote full, even growth, especially for leafy crops like lettuce. The support mechanism must be rigid enough to keep the plants upright but also strong yet flexible enough to allow all parts of the plant to grow.
Baskets are a popular option, especially where plants are introduced as seedlings. Closed cell foam plugs are also suitable for starting directly from seed. Seeds are placed in the plugs, which in turn are inserted into holes in the tray that forms the top of the growing chamber. The tray is exposed to light on the top side and nutrient mist below. Flexible foam secures the stem and root mass as the plant grows.
Flexible collars are also popular for hydroponics systems. The collars encircle the stems of seedlings and can expand or be compressed automatically as the plants grow. Circular holes in a larger tray support the collars, allowing for easy movement into other environments as they grow, for cleaning, or for harvesting. The ability to easily move plants without damaging either the foliage or the roots is an important part of the success of aeroponics.
Fruiting plants like tomatoes and strawberries, or root crops like potatoes are also well adapted to aeroponic systems. Tomatoes, squash, and other plants that produce heavy fruits do need additional support beyond a simple foam collar, so they work really well in a tower system where roots face inward while the foliage and fruit are supported by an external supporting structure, very much like a traditional wire tomato cage. When fruits are particularly heavy, growers may choose to provide individual support with an expandable mesh bag, for example.
Potatoes are an important cash crop and global food source, and there’s actually been quite a bit of study around the world on optimizing potatoes for aeroponic farming. This allows developing countries where soil fertility, water quality, diseases and pests are problematic to improve both quality and yield. Aeroponics setups are also very space efficient, meaning that high levels of production can be supported even where land is in short supply.
Root crops have different needs than top fruiting plants and they’re not as easily adapted to hydroponic systems since tubers can’t be constantly submerged in water. In aeroponics, however, tubers are allowed to grow suspended in air, where the abundance of oxygen produces vigorous root masses capable of supporting tubers. It’s advisable to select varieties that produce many smaller tubers vs a few very large (and heavy) ones.
Starting From Seed:
Starting from seed in an aeroponics system is actually fairly straightforward. A flexible foam collar placed in the aeroponics tray can hold even tiny seeds, keeping one side exposed to light and the opposing side regularly misted with water enriched by nutrient solution. Given appropriate conditions like ambient temperature, seedlings typically sprout earlier than those grown in soil. As the seedling grows, the foam collar adjusts to the changing size of the stem and the availability of oxygen in the root system promotes vigorous growth. This is a big advantage in aeroponics since root growth is a critical factor in the health and survival of seedlings, especially during the necessary transplanting of many soil-grown plants.
Room to grow:
Aeroponically grown crops even have an advantage over many hydroponically grown crops because their support system is so flexible. Whether starting from seed, sprouted seeds, or very young seedlings, a flexible foam collar is secured around the seed or stem. The collar itself fits into a tray that separates the enclosed root chamber from the (usually open) top chamber. These flexible collars allow the plant to grow freely without restricting stem size or the need to transplant. As the crown and foliage of a plant becomes larger, it’s a simple process of transferring the plant to a roomier environment by lifting it by the collar and inserting the plant into a new, roomier tray. Since there’s no growing medium, neither the roots nor the foliage are disturbed by the move. The process is quick, simple, and trouble-free.
Misting
Aeroponics setups typically keep a reservoir full of carefully balanced nutrient solution underneath the suspended plants. A system of pumps and nozzles periodically draws the solution up and sprays a fine mist, completely covering each individual root system. Any solution that is not absorbed drips down and returns to the reservoir. Since the roots are misted only periodically, they spend the majority of their time exposed directly to oxygen, which is a key factor in the success of aeroponic farming.
Another key factor in the success of aeroponics is the size of water droplets provided in the misting system, since smaller droplets are more easily absorbed by the plants. All aeroponic systems are based on root systems suspended in air within a closed chamber, and periodically exposed to sprays of nutrient-enriched water, but different types of equipment support different size mist, from basic low-pressure systems typically employed by casual hobbyists to high-tech systems that produce droplets fine enough to appear more like fog than mist. The bushy, abundant roots associated with aeroponics are an effect of, as well as a driver of abundant plant growth. A combination of plentiful oxygen and fine mist nutrient solution promotes generous root growth, and in turn, the roots have even more surface area to absorb both oxygen and nutrient solution. The advantages convey not only to root formation but also to a faster growing plant canopy and copious fruit development.
A key element in operating an aeroponics system is carefully timed spray intervals and duration. Oxygen exposure is the key to success for aeroponics, but the plants still require nutrients and water to support growth and maintain turgidity. This means that reliable, programmable timers are critical for any sort of large-scale aeroponics operation, and since plants will quickly die in the absence of regular mistings, backup power systems are a must.
