What are some tips, methods, facts that I need to know about starting a rooftop garden?

She is going to want something to put the plants in, check out meijer.com they have a nice framing system she might like as well as some removable greenhouse top that will extend the growing season for vegetables. http://www.meijer.com/s/frame-it-all-hard-sided-greenhouse-with-4x4x12-raised-bed/_/R-171432

I would also check out the growing season for NYC with the different veggies and that she would like to grow, a way she can do that is going to a seed website. Here is the like to Burpee http://www.burpee.com/?cid=PPC I have used them for around here.

I do alot of planting on my balcony and plant tomatoes, cucumbers, lettuce, eggplant, spinach, squash, beans and etc.

Oh she is going to want a way to bring water to the plants, they will need to be watered in the morning and the evening.

I hope this helps

There is come cool ideas for planting recycling bins and using self-watering irregation systems. You will want to read up on sub irregation systems. You can make planting boxes out of plastic tote boxes, recycling bins, etc. and water them from the bottom, saving water. You can also put in a rain barrel and use a drip irregation system using rain water. The soil mix for square foot gardening yields a lot of produce.

http://www.bucolicbushwick.com/

Make sure it is ok with the building manager before you start. They may have to make repairs or modifications to the roof before you start loading it with lots of dirt.

Dirt can be heavy and if the roof has a weak spot or two it will lead to leaks at best.

You need to water regularly, because the plants tend to dry out quicker.

Here is an article from The City of Chicago called A Guide to Rooftop Gardening.

There is also the issue of soot and other serious pollutants and the need for some shade. The sun really can bake a rooftop garden.

I tried a small garden on a 12th story balcony. One small birch tree and containers of flowers only. I found it impossible to maintain.

Learning to companion plant might be even more important when doing a small scale, limited space garden like on a roof top. Basically, companion planting involves allowing plants that naturally cooperate to do so, often cutting down on the need to fertilize and water. It often makes the plants more productive, too, both nutritionally and in bulk produce. Just make sure the plants do cooperate.