In re this query:

Friend of a friend quit putting out thistle seed; she was getting
thistles growing all over her property. Then she was told that if she
baked the seed for 15 min at 350o they would not germinate; but, were
still good to eat.

True?

I have been informed that true thistle-seed is virtually, perhaps
absolutely, unavailable on a commercial basis. The bird-food commonly
called "thistle seed" is actually Black Niger seed, a much different
and far less noxious plant. I have not seen Black Niger seed germinate,
but do not doubt that this might occur. This, and probably most other
seeds, can be rendered non-vialable by exposure to 350-degree F heat.
However, to have this effect, all seeds must be exposed to this temp-
erature for the prescribed time. Thus, the seeds must be spread out
on a broad surface rather than piled up (which could insulate seeds
in the center of the pile).

Here in Southeast Texas, Black Niger seed is commonly used to feed
American Goldfinches, which species competes poorly with House Finches
and House Sparrows at feeders with ports large enough to provide
Black Oil Seed. However, Goldfinches show a clear preference for Black
Oil Seed over Niger Seed when House Finches are relatively few and
House Sparrows are precluded from using the feeders.

With apologies for a long reply to a short question.......

a Buaidh!
FX

F. Schloeder
Bellaire, TX