Several bio-fences have been put up at various parts of the plot, by attaching iron wire-mesh between evenly spaced pipe-pillars at the Puliyarakonam plot in Thiruvananthapuram.    They function as vertical gardens because different types of fruit- and flower-bearing as well as medicinal climbers and creepers have been trained on them.   The fences have proven to be sturdy enough to hold even pumpkins, whose creepers are generally left to grow on the ground.