Kate Hudson wishes son happy 16th birthday: 'You still have two years under this roof'

Kate Hudson celebrated her son Ryder Robinson's 16th birthday on Tuesday by sharing an adorable throwback video of him as a baby.

The actress and mother of three, 40, attached a sweet message reflecting on how much her oldest has grown.

"I didn’t realize it would be here so fast! 16 years today. 16. I will savor these next couple years before he flies the nest," Hudson wrote about Ryder.

"People sometimes get sad on days like this," she continued. "Time creeps up on us and rocks us a bit, reminding us that the years don’t wait for us to be ready. Well, RYDER IF YOUR READING! I’M READY!!!"

The home video features Ryder on his second birthday blowing out the candles of his birthday cake.

Hudson also shared that she is "excited" for her son's future, describing him as an "amazing young man" in her message. "I am honored that you chose me to be your mother," she wrote.

"Here’s the thing...you still have two years under this roof. My roof, my rules ;)" she added.

Ryder is a fixture on his mother's Instagram page. The "Almost Famous" actress, who is also mother to 1-year-old Rani Rose and 8-year-old Bingham, recently shared her family's goofy holiday photo, which he can be seen in striking a pose in a festive outfit alongside his siblings.

"We take Christmas MERRY seriously..." she captioned the shot. She also shared a photo of Ryder holding his little brother Bingham on his shoulders.