All the greenhouses around Leamington do use hydroponics.

Interesting. I'd be curious why they'd do that given the high quality soil available...

It's hard to google for, but it appears that hydroponics allow for more crop per acre. So the article is actually conflating greenhouses and hydroponics (outdoor hydroponics seems to be very rare, so the latter more-or-less implies the former)

I can grok that, but it's not like land is at a premium in Canada, and hydroponics is generally very capital intensive.