This describes the process whereby an awkward stem, that is not suitable for pleaching in the conventional way, can still be laid by severing all but one of its roots and rolling it over so that the attached root twists but stays attached. In order for a conventional pleach, there needs to be a good run of live grain on the face of the stem which will become the hinge. Only if this is not available should a root-lay be considered.
The stem in the picture has a dead section on the face meaning that a suitable hinge cannot be created by pleaching. The way that the roots can be seen to run from the stem make root laying a possibility.
This shot is looking square at the hedge and the stem needs to be laid to the left as the blue arrow shows. Graham identifies the root, arrowed in yellow, that is running out perpendicular to the hedge, as being a suitable one that will twist as the stem is allowed to drop. All other roots, particularly the large ones to the right, are severed from the stem and it is laid over and built into the hedge in the normal way. As it drops, the attached root naturally twists but remains intact. Clearly, the severing cut needs to be made below the chosen root.
Here we can see the finished configuration. The yellow circled root is the twisted, attached one that will continue to sustain the stem. The severed roots circled in red will throw up new shoots in the same way that the heel of a conventionally pleached stem would. In practice, it is often the case that the roots of a stem need to be exposed by carefully digging around it, and this takes time. Here, Graham was lucky that the roots were already clear above ground level and a suitable root was already presenting itself.