I can not see anywhere that it says you can not but the very name "Kitchen Scraps" that implies the limit.
Has anyone noticed the price to buy the bags? They are not cheap. We use one every other day, which would be 180 a year. That is six boxes of 20 or about $130 a year extra cost.
The cards that were mailed out to residents do not specifically forbid garden waste, but they do not include it, either. The closest things are "houseplants" and "flowers."