Colorado voters in November 2012 legalized the possession, use, production, distribution and personal cultivation of marijuana.
KMGH-TV, Denver, said there won't be any actual marijuana at the fair -- the judging will be done off-site with photos showing the winning entries. The entries will be shown in a "Pot Pavilion" open only to people 21 or older, the station said.
There also will be a joint-rolling contest using oregano.
County fair organizers told the station the marijuana categories will add a fun twist on Denver's already eccentric county fair. The event already includes a drag queen pageant and tattoo competitions, KMGH said.
Judges looking at marijuana plants will look only at quality, not potency, the report said. Top prize is a blue ribbon and $20.
The Denver County Fair began in 2011.