The breadth of use that Eucalyptus trees provide is astonishing !
Interested in buying Eucalyptus foliage
Nicola Brown provides workshops on the subject, though you can get a good idea of the process from her video below which also shows the beautiful results that can be achieved
Many of the Eucalyptus that can be grown in Ireland and Europe are suitable for use in the process of dyeing clothes and fabrics:
are a few that Nicola has tried successfully, and which she describes as producing the most amazing reds π though there’s always merit in experimenting, and personally I like the unusual foliage of the snow gums such as:
NOTE I am going by the shape and patterns on the leaves; I do not know if they will produce good dyes.
NOTE also that the bark as well as the leaves of Eucalyptus can be used for fabric dying π

More information about fabric dyeing with Eucalyptus can be found at Nicola Brown
Another good resource, particularly in respect of which varieties produce different colours in different fabrics is Sally Blake