The former 'Gossip Girl' actress claimed the key to the glossy locks sported by Hollywood stars is to use hair masks on a regular basis after shampooing in order to maximise moisture.
She told Vogue.com: "I don't know anyone who uses conditioner in my industry."
Instead, Blake buys one set of shampoo and hair masks dedicated to hydration and another for strengthening and alternates their use.
She said: "Your hair needs two things, strength and moisture."
The 36-year-old star - who has four children with husband Ryan Reynolds - discovered the technique after her first acting job caused severe damage to her tresses.
She said: "It was just so damaged and destroyed.
"A hairstylist explained to me that this process could save it. If you give hair strength, you give it foundation, structure, and stability. But if you only give it strength, it's going to become brittle and hard. So it also needs moisture and elasticity. But if you give it too much, it'll break."
Blake is launching her own range of haircare products, Blake Brown, an eight-item collection which includes two shampoos and mask sets, as well as a pre-shampoo treatment.
She said: "People think of hair masks as more of a specialty product or a one-off treatment.
"But I use it every single time like I use conditioner.
"I live by the principle that if you take from something, you have to give back to it. And that applies to my hair, too. So if I take from it by styling it or really wearing on it, then I give back to it."
The 'Sisterhood of the Travelling Pants' star explained the origins of her brand's name pays tribute to her dad.
She said: "I wanted to put my name on the brand because it's something that I hammered, carved, welded, moulded, and baked.
"But I didn't want to rely on my name alone. So it's a version of my name—my dad took my mom's last name—Lively came from my mom and Brown came from my father."