Who needs soil to sow a sustainable garden? You can cultivate plants in mid-air, float them in mineral-enriched water or add nutrients for an organic harvest by using your own fish for the fertilizer.
All of these methods can be done indoors and year-round.
Hydroponics may 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.