The colour palette for children’s TV is very green, isn’t it?
There are two reasons for this. One, many of the shows are set outside, which encourages kids to play outside too. It is a shame that this is not a given, but there we go.
Second, many of the programmes mix live action with animation. The easiest way to insert a person into a make-believe world, or bring an imaginary character into the real-world, is to use green-screen technology. If there is lots of grass in the set (imaginary or otherwise) it makes the job of the CGI teams easier, and it makes the resulting product better. It’s interesting that this technical requirement should mean that more programmes for kids are set outside.