View Photo Gallery: For eight years now, residents and guests of Riderwood retirement community in Silver Spring have gathered to play bluegrass, roots and country music. The musicians began informally in a small classroom and now perform every few months, or whenever they feel like it, in a 200-seat performance hall for residents and guests.

I dropped by a bluegrass jam the other night. The venue: the Riderwood retirement complex in Silver Spring.

Concert goers came by foot, slowly. Others came by electric wheelchair, fast. (Some of those things can really scoot.) I sat in the back of the huge activity room, and pretty soon there were 250 people in their seats waiting for the band to take the stage — a real stage, with real lights.

The hour-plus jams have taken place every few months at Riderwood for eight years, having started in a little classroom that quickly proved too little for the booming demand of retirees for downhome bluegrass music. A bigger venue near the dining room was found, but that also was too small. Now the jam sessions unfold in a room big enough for a wedding.

Henry Plotkin, 85, plays the fiddle. He’s a resident at the Riderwood retirement community in Silver Spring. ( Lisa Bolton/The Washington Post)

Bruce Clark, a Riderwood resident who plays banjo and guitar, tapped on the microphone and said, “Anyone who can’t hear me put your hand up.” This statement, given the number of hearing aids in the room, prompted much ironic laughter.

“We’re gonna start off in the key of D for all you quality singers out there,” Clark said, fitting his guitar strap around his neck. “This is one of the themes that reoccur in bluegrass. It’s about a poor old boy whose gal done left him, and he’s just too damn dumb to figure out what he did wrong and why she left. It’s called, ‘I Know What it Means to Be Lonesome.’”

Guitars strummed. Fiddles fiddled. The sound was delightful. Clark’s domestic partner, Pat Kral, was off to the side strumming her auto harp. Clark sang: “Oh I know what it means to be lonesome, and I know how it feels to be blue, and I know what it means to be lonesome in my dreams when someone else is kissing you.”

In the audience, feet tapped on the floor. Heads bobbed up and down. People tapped on their knees. My colleague Lisa Bolton, who took the wonderful pictures in the slideshow above this post, smiled to me, and I smiled back. And I sent the following text message to my wife: “This is so undeniably sweet. I wish you could see this.” She wrote back, “Take video.”

I did.

Here’s a clip of the band playing “I Know What it Means to Be Lonesome.”

And below is a video of the highlight of the show: 85-year-old Riderwood resident Henry Plotkin strumming his fiddle like a 22-year-old busker outside a subway station. Plotkin is a former physicist at NASA. He played the fiddle decades ago at MIT to earn some extra cash. He absolutely blew me away.

The band has another gig at Riderwood next month. I think I will take my wife there on a date. I can’t think of much else that would be sweeter.