As Denver musician Wes Watkins booked springtime shows for his gospel-tinged band the Other Black, one date on the calendar took absolute priority.

"I decided that we had to play 4/20," Watkins said of the stoner holiday known as 4/20, or April 20. "We played last 4/20 at 11 o'clock at night, and it was a laid back and silly show because everybody was so tired and stoned.

"This 4/20 we're playing a brunch show at the Larimer Lounge because it's also Easter. And like Easter, 4/20 is a date that speaks for itself."

Especially in a Denver with nearly four months of legal recreational marijuana sales under its belt, 4/20 — the calendar equivalent to 4:20 p.m., the time pot smokers would historically toke up — does speak for itself. And it speaks in a language of music festivals, unseasonably early Red Rocks shows selling out a month in advance and themed concerts sponsored by the biggest marijuana companies in the state.

April 20 is now a full-on entertainment holiday in Colorado with promoters and entrepreneurs looking to capture a slice of the massive audiences in the same way they might on Halloween or New Year's Eve — and music fans are the winners with a dizzying array of music throughout the city.

"We've got the concert at the sculpture park, shows at Red Rocks and if you look at any of the band-oriented clubs and even the dance clubs they have a theme to their nights this weekend," said Brian Kitts, spokesman for Denver Arts & Venues, the division of the city that manages venues like the Denver Performing Arts Complex and Red Rocks. "4/20 has become another way to market music."

Just how in-the-know is Denver's 4/20 with national trends? The current High Times magazine cover features Mount Kushmore, a Mount Rushmore-styled photo of Snoop Dogg, Cypress Hill frontman B-Real and Method Man & Redman — "the four godfathers of weed culture," said the magazine's editor-in-chief Chris Simunek. All four MCs are playing unrelated 4/20 shows in Colorado this year, and Snoop and Method & Red are each doubling up with two shows in one day.

And it doesn't stop there.

In the past week, rappers Ice Cube and Too $hort, comedians Cheech & Chong and Andy Haynes and the actor who played McLovin in "Superbad" (Christopher Mintz-Plasse) have played 4/20 shows in Denver. The list of those yet to play this weekend reads better than any New Year's Eve lineup in recent Colorado history:

That list includes Snoop, Wiz Khalifa, Wyclef Jean, Slightly Stoopid, Matisyahu, Mac Miller, Karl Denson's Tiny Universe, Talib Kweli, Leftover Salmon, B.o.B., Method & Red, Julian Marley, Paper Diamond, Nappy Roots, Collie Buddz and Pato Banton.

Denver 4/20 rally
In this April 20, 2013 file photo, members of a crowd numbering tens of thousands smoke marijuana and listen to live music, at the Denver 420 pro-marijuana rally at Civic Center Park in Denver. (Brennan Linsley, Associated Press)

"Weed culture"

It's a lot of hip-hop, but rap music and weed culture have long walked hand-in-hand.

"The hip-hop community is where you're seeing 4/20 thrive the most because it's been a part of weed culture for a long time now," said Robert Castro, founder and managing editor of Colorado-based music blog Ultra5280. "The weekend around 4/20 has become a hub, and (4/20) really started picking up steam in Colorado two or three years ago as all the dispensaries were taking root."

A very local example of 4/20's growing presence: At least four entirely new music festivals will take over Denver parks and clubs this weekend — from Daze on the Green to Festival 64, Dabroots to Waldos Music Festival — debuting this year in hopes of capturing an audience and potentially returning next year.

Another example: In 2013, Red Rocks hosted its first-ever 4/20 concert with Cypress Hill and Slightly Stoopid. They called it "Hotbox at Red Rocks," co-opting a popular stoner term for getting stoned in an enclosed space, and the show sold out. This year the mountain amphitheater will host two sold-out shows on April 19 and 20 — not to mention the venue's annual Easter Sunrise Service on the morning of the 20th.

"There's an underlying theme going on (in those concerts), but for us it's another couple concerts," said Tad Bowman, Red Rocks' venue director. "I'm excited that we have a show on Saturday night, Easter Sunrise Service on Sunday morning and another show on Sunday night — regardless of the shows' theme."

Cannabis Cup

The biggest 4/20 events in Colorado are the 420 Rally at Civic Center and the Cannabis Cup, a sprawling trade show for all things marijuana at the Denver Mart. Both events run April 19-20, and both are pumping more money into their 2014 music offerings than years past.

Both Red Rocks shows are tied to the Cannabis Cup, which sold out last week and is expecting more than 37,000 people over two days, as was their Friday night show with Ice Cube and Action Bronson.

"There's more entertainment going on this year in Colorado than past 4/20s," said Jen Bernstein, managing editor of High Times magazine, which presents the Cannabis Cup. "And if you can't get a ticket to the Cup, there's plenty else happening."

Matisyahu is headlining the much-hyped Waldos Music Fest on April 20, an event prominently sponsored by marijuana companies Dixie Elixirs and Native Roots Apothecary. The expansion of 4/20 was part of what inspired Dixie managing director Tripp Keeber to create event production company Munch & Company, which is producing the Waldos festival and other events this weekend.

"We've been approached by half a dozen music festivals around the country where they'll have Jack Daniels, Marlboro and now they're specifically reaching out to Dixie — not for retail sales at their event but for brand awareness."

For Denver musician Watkins, whose Other Black will headline an Easter brunch show at the Larimer Lounge, 4/20 remains a sacred day for his art and his family.

"We're musicians," Watkins said, "and all our friends are stoners. But at the same time, this Easter show will be the first time my grandma will have seen me play since high school.

"It'll be an interesting combination of cultures, older and younger, and it'll force some people to get over their biases, which is what I'm all about. My grandma is like, 'Weed smokers, blah blah.' But I smoke weed every day, and she still loves me. So she and her friends will be at our show with their Sunday hats, and I'm excited to hang out with her on 4/20."

Ricardo Baca: 303-954-1394, rbaca@denverpost.com or twitter.com/bruvs