Using grass sod for potty training for apartments

I've tried using puppy pads (lying in a doggy litter pan) sitting outside on our balcony, but we've read that the pads might be too similar to carpet to a puppy. Also, unless you dispose of a puppy pad after each use (and I'm sure a lot of people have tried to use the same pad for multiple pees), the puppy will often track the wet pee from the pad. Puppies also often like to chew on the pad.

I finally switched to grass sod, and I've found that this works great! Kushi took to it immediately, and she learned that grass growing elsewhere is also good for going potty.

There are many websites which sell sod boxes, usually for an exorbitant price (~$200), but you don't need them. Just lay out a plastic tarp/sheeting and get a 3 x 3 foot worth of grass sod (e.g. at your local Home Depot), which will all cost less than $5, to put on top of the tarp.

I replace the grass once a week and very lightly sprinkle water over it once during the week. The grass is still fully green after a week, so I guess you could try extending it longer, but I prefer to replace it weekly to keep everything more sanitary.

The only drawbacks to using sod are that hauling around the sod is really heavy, and in warm weather, some flies will swarm over the grass (the flies disappear in the cooler weather).