Who needs soil to sow a sustainable garden? You can cultivate plants in midair, float them in mineral-enriched water or add nutrients for an organic harvest by using your own fish for fertilizer.
All of these methods can be done indoors and year-round.
Hydroponics might be the most familiar soil-less gardening technology. It involves growing plants by floating their roots in chemically enhanced water. The operation can be automated with a timer. Some systems are portable.
Aquaponics blends aquaculture (feeding fish in tanks) with hydroponics. Water heavy in organic animal waste is pumped from a fish tank into grow beds where plants filter out the nutrients. The purified water is then recycled back into the fish tank, where the nitrate-production sequence is renewed.
Aeroponics uses no growing medium. Instead, plants are strung over containers and their roots are misted with a nutrient-heavy solution.
"The technology that is accelerating this (soil-less) trend is the proliferation of extremely effective and increasingly energy-efficient grow lights," said Sylvia Bernstein, owner of The Aquaponic Source in Longmont. "With today's grow lights, any space can become a year-round garden."
The systems are easy to learn and to maintain, Bernstein said.
"First, there is no weeding involved. And because you can set your grow beds at whatever height works best for you, stooping and bending can also be minimized," she said.
Watering also is easier, especially with aquaponics. "You simply top off your tanks once every week to 10 days, versus the nearly daily watering that an outdoor garden requires," Bernstein said.
Hydroponics is an uncomplicated way to raise vegetables, said Richard Tyson, Orange County (Fla.) Extension director.
"The floating system is one of the most inexpensive, low-tech systems around, and as long as you stick with leafy salad crops and herbs, it is one of the best for beginners," Tyson said.
As for aeroponic gardens, they need little space, making them popular with apartment dwellers. Their moist environment is vulnerable to bacteria growth and disease, though, so they must be kept clean.
Nearly any freshwater fish that thrives in captivity can be used for aquaponic gardening, from goldfish to catfish and trout to crayfish. The fish can be purchased from licensed hatcheries, while aquaponic, hydroponic and aeroponic kits are available at specialized supply stores and online.
"The best fish to grow in aquaponics are the fish that best suit your needs, whether those be for food or fun or both, and that are conducive to growing the plants you are interested in growing," Bernstein said.
Fast-growing tilapia are the most commonly used. Bernstein has trained her tilapia to eat from a baby bottle, which provides a degree of entertainment. And, she noted, "you always can eat the full-grown fish."
"In the not-so-distant future, I believe that indoor, aquaponic gardens will become more the norm than the exception," Bernstein said. "Homeowners will start to think of them as a part of their food preparation environment, much like a living pantry."