Time and again we have seen tall vertical and unstable banks that are too high on top to plant riparian shrubs and too unstable to plant shrubs at the water's edge. We wanted to establish plants in these areas without using heavy equipment and re-grading vertical banks. We have also seen grass and sedge plants out compete our newly planted shrubs in multiple instances (which is why we have almost exclusively used 5-gallon shrubs since 2010).
To create a pod we select an area behind an eroding bank were we want riparian shrub establishment even as the bank erodes. We place the pod several feet away from the eroding bank, depending on the rate of erosion as we would like the plants in the pod to establish before the creek or river reaches the pod edge.
We dig the pod by hand and choose a size based on the number of plants and the size of the bank. Sometimes we make many small pods, say 3 feet in diameter, or other times make a few large pods, say 20 feet long by 8 feet wide. Any size can be effective. We remove the vegetation and its roots from the surface and place those clumps upright and away from the pod. This allows for the clumps of vegetation to re-root into the soil and leaves less area for weeds to establish. The pod would typically be 8 to 12 inches deep after removing grass roots. We then either dig the entire pod 8 to 24 inches deeper into the soil, removing mineral soil or we begin to dig deep holes in which to plant a 5 gallon shrub. Willows especially can handle the ultra-deep holes and we fill the hole after planting back up to the pod ground level while burying part of the willow stem. If we are planting species such as golden current, cottonwoods, or woods rose we typically dig the pod deeper and dig shallow holes for individual plants.
We typically plant a single species in each pod and judge our depth based on what species we are planting. We try and nearly reach the water table while being careful not to plant shrubs too deeply where the pod may fill up with water and be wet too long for any woody plant. Typically one can find where the anaerobic soils begin and we try and plant above that level.
We have used a mini-excavator in one instance where the grass mat was so great that digging by hand was too difficult. Of course a person could use heavy equipment and plant using all sorts of methods similar to this but we prefer to minimally cause further disturbance or create areas where weeds thrive.