Now that Gardening and Landscaping is in beta and going quite well any question that fits their site better should really be migrated. Normally questions aren't migrated to beta sites but if they'd only be closed as off topic here then I think it's worth it.
Firstly it'll help keep our site on topic.
Secondly it'll help drive traffic to their site - always a good thing.
So if you spot any, post it in an answer here and I'll liaise with the moderators over there to see if they agree. Yes you could just flag the post, but this way we'll have the evidence to back up the need (if there is one) for a permanent migration path set up on the close dialog (once Gardening migrates from beta) that's accessible to all 3K+ users not just the moderators.