Two points.

First, this is a very bad situation for a junior designer since they basically get no mentorship. The studio model is very important for developing design talent. Don't take on junior talent without senior talent if possible.

Second, expecting designers to code, a common meme repeated often on hackernews, is even more disastrous in this case; they are overloaded already with design work (and even if you have a few designers already, they will still probably be your bottleneck).