Denise Richardsis making sure to celebrate her daughter Sami on her birthday.

On Wednesday, theReal Housewives of Beverly Hillsalum, 51, paid tribute to Sami in honor of her 18th birthday with a sweet message onInstagram. In the post, Richards shared a recent shot of her teenage daughter along with a few pictures from her childhood.

“In a blink of an eye you’re 18…. !!!! Happy Birthday my beautiful Sami. I love you so much,” writes Richards. “Privately many more words to share with you. I love you unconditionally and I am very blessed & grateful to be your mom. And Nana is looking down celebrating with you🎂I love you my sweet Sami💗 Happy 18th Birthday!🎉🎂🎊🎁😘”

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Richards' birthday post for her daughter comes one month after she shared on SiriusXM’sJeff LewisLivethat the pairhave a “strained” relationship.

“Honestly, I have a strained relationship with her,” admitted Richards, who also shares daughter Lola, 16, with ex Sheen. “It’s very difficult. I know we’ll get back to where we were eventually but right now, it is strained.”

Denise Richards/Instagram; Inset: Steve Granitz/WireImage

Denise Richards, sami sheen

Asked whether Richards was happy about Sami’s current living situation, the actress said, “Obviously I would love for her to live with me. She lived with me all these years.”

“But I think it’s very difficult raising teenagers now and especially in Los Angeles when there’s access to everything. We didn’t grow up with Postmates and Uber where you have everything that you want,” she continued. “There are certain rules and I enforce them. And [at Sheen’s], there’s different rules at that house and that’s okay.”

Rich Fury/Getty; David M. Benett/Dave Benett/Getty

Denise Richards, Charlie Sheen

Back in October, a source told PEOPLE that at Sheen’s household, Sami and Lolatend to have more freedom, whereas Richards and husband Aaron Phypers set more rules at their home. (Sami, in September,referred to Mom’s place as a “hell house"where she felt “trapped” before moving in fully with Sheen.)

“She would love for the kids, when she has to film, to stay in her nice house but they go to ‘Wonderland’ where they can get anything they want,” said the source, who claims that “everything is a big party” at Sheen’s house.

A separate source, however, said, “Charlie is a terrific dad and his daughters adore him. They enjoy being with him. Charlie is a strict father but fair. The girls have rules at Charlie’s house, which includes homework and curfew. The girls are polite and smart and funny and a joy to be with.”

source: people.com