Umm they have a website and phone number
The spring native plant sale at Hawk Mountain Bird Sanctuary is May 19th and May 20th from 10 a.m. to 4 p.m.
Actually it's not on their website, at least not on mobile that I saw and I searched for a while. In searching "native plant sale" in the search bar on their website, though, I saw past dates that were all May and September, so I would guess there would be sales then. If you call they will probably have more information. Hope this helps!
Dates and times are prominently featured on the facilty website.
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