No - it's a bit of experimental eco-friendly dyeing. One of our group members recently attended a workshop given by the Australian textile artist India Flint who dyes all her own fabrics using plant material and no chemicals at all. She gathers her leaves, flowers, bark, lichen, etc. and places them between layers of fabric which are then tightly rolled and bound so that the fabric is in very close contact with the plant material. The bundles are then boiled for about 1 hour - I think that is right, anyway it's what I did. White vinegar gives darker colours so I added just a dash to my boiling water. I used bits of old sheeting, and oddments of silk cut to approximately A4 size.
Silk and wool give better results, cotton is not so good. I tried some ripe honeysuckle berries which produced these yellow blobs. They are brighter in reality and look better than this photo which looks like a very dirty tablecloth!
Colours from previous layers seep through onto the next one. Here I think are very faint marks from red rose petals. I wonder if I had used a newly opened flower instead of one which was beginning to fade I would have got a stronger result. Maybe I didn't roll or bind them tightly enough.
Spent day lily flowers give quite a strong colour. Strange that they come out purple when the flower was a rich deep red.
However, I am pleased to have had even mild success from such sketchy instructions and must look into this in greater detail. Obviously a knowledge of which plants to use will be essential rather than just going round the garden and hoping for the best. Possibly picking leaves at certain times of the year might make a difference - I'd better buy India Flint's book!