Well these are your plants for blue..... including the wonderful Woad.
The Woad which I have used can be made into so many different blues, by adding yellow you can make a great duck egg colour and you can make so many variations.
Give it a go! I am going to be doing some great experiments with all this new found knowledge!
NATURAL DYE PLANTS FOR BLUE
Devil's Bit (Scabiosa succisa) Leaves prepared like woad
Dog's Mercury (Mercurialis perennis)
Elder (Sambucus nigra) Berries
Indigo (Indigofera tintoria)
Privet (Ligustrum vulgare) Berries with alum and salt
Red bearberry (Arctostaphylos Uva-Ursi)
Sloe (Prunus communis) Fruit
Whortleberry or Blaeberry (Vaccinium Myrtillus) Berries
Woad (Isatis tinctoria) Yellow Iris (Iris Pseudacorus) Roots