Reese Witherspoon penned a beautiful tribute to son Deacon Phillippe for his 18th birthday, along with his photos taken over the years.

The actress couldn’t believe her son is now grown up saying, "One day he was trading Pokémon cards, singing Bruno Mars songs, and playing American Ninja Warrior in the backyard. The next day, he is taller than me, cooking the family steaks on the grill and making his own music with his best friends.”

Witherspoon shared more pictures on Instagram Stories, including a lovely family photo featuring herself, Deacon, and ex-husband Ryan Phillippe.

Deacon posed in between his mom and dad with a round layered cake in front of them.

The actor also marked the special occasion by posting snaps from the celebration and gave a shoutout to his ex.

Witherspoon commented to the post saying, “So proud of our boy ... I mean our ADULT Son! 😮❤️”

Witherspoon and Phillippe, who share two children tother — Ava and Deacon, married in 1999 and divorced in 2008.

Witherspoon, who is also a mom to Tennessee James, married Jim Toth in 2011.

Witherspoon talked about her kids in a past interview saying, “I never expected the kind of relationship that I have with them, but it's so rewarding to be able to have kids that you can process life with a little bit, and they help me understand the complexities of what it means to be a human now. So I'm really, really grateful that these little humans are in my life.”