Clean scalp for hair growth? + silicone removal

Is it important to have a clean scalp for hair growth? Is simply brushing my hair good enough or do I actually need to use shampoos that clarify? Also if I’m using products with dimethicone do I have to use shampoo on all my hair? When I use shampoo I only use it on my scalp… but I use the silicones on the length of my hair so would I have to shampoo the length of my hair? What ingredients do I have to look for to find a gentle shampoo that will also remove the silicone?

I personally do not like washing my hair much. I usually just use conditioner whenever I wash it (my hair is curly) and then I try to brush it often to distribute the oils down the shaft. Do I have to start washing my scalp more to see more hair growth? Is CO washing sufficient for the scalp? And if it’s not sufficient for the silicones? I do apply a silicone serum to the ends of my hair after washing before blow drying.