If you do farming in space, you have many problems. You have to get the food down, and water up, you have to bring up all sorts of materials and store them in space... It is much easier to get light down than to get seeds and water and nutrients up, and then food back down again.

If you get light into a clear material which has a reflective surface( almost any clear material does ;) ) then the light will reflect internally and flow down the material, while seeping out the sides. That is how fiber optics works, but it doesn't have to be fiber, almost any clear material would do...