First, the HSA Member Anthology deadline is May 31st, even though the website says May 15th. I thought I'd missed the boat, but have confirmed that a deadline of May 31st was published in the print newsletter, that is the "real" deadline, despite what the website says. The rest of the information is accurate, however. So, if you're a member of HSA and haven't sent those haiku in, please do so! I enjoy the member anthology because I see it as a sort of "yearbook," providing a snapshot of the breath of haiku the members are writing in a specific year.
Second, the Yuki Teikei Haiku Society is having its annual haiku contest with a deadline of May 31st. It's a bit challenging for me because in addition to following the normal seasonal attributes of traditional haiku, this contest also requires 5-7-5 syllables.
Finally, even though the deadline isn't until June 30th, why not submit a short sf poem about mirrors to the SFPA Poetry Contest?