Not all haiku-related journals are open to rengay or other linked verse, so it can sometimes be a challenge to find venues that welcome rengay. The following are print and online journals that do welcome rengay, with links to their submission guidelines. If you know of other journals that publish rengay, please let me know.
And of course, don’t forget the annual Haiku Poets of Northern California rengay contest, with a deadline of 31 January each year, with results published in Mariposa (this contest started in 1995). You can also see past HPNC rengay contest winners and commentary on the Haiku Foundation website and on the HPNC website (click Contest, click the year of results you want to see, and then scroll down to the rengay section). The Haiku Society of America also runs the Garry Gay Rengay Contest, with a deadline of 31 May (started in 2020). And who says you have to limit yourself to the preceding haiku journals and contests? Mainstream poetry journals might well be open to rengay as well.
Note: For links to other haiku and related journals, please visit my Links page on Graceguts, which lists numerous journals (although not necessarily open to rengay). See also Contests, Publications & Groups on the New Zealand Poetry Society website.