Plants are not suseptible to water conditions like fish are.....they are going to be ok in ammonia conditions so they are alright from the start. Now when you say fishless which method are you reffering to......the one using fish food or the one using bottle ammonia. If you are using bottled ammmonia then there will be no waste material for the plants to use as food.
Also another note....having plants in the tank during a fishless cycle will also slow down the whole process as the plants will use the food that you place as food itself aonce it is broken down, and you wont have as much to get the ammonia levels up
I for one dont care for fishless cycling, I always use established materials from other tanks to get mine going. If I was to start a new tank from scratch I would do it with some feeder goldfish as they will be alright to get things going and if things go a muck then you are out very little in the lines of fish.
HTH
Les