Yes, you should be able to. Also remember if you cannot: tomatos do really well in a nicely sized pot, and a stake.

Check this out!

www.yougrowgirl.com

lots of good advice on urban gardening.

sorry about the link.

just wanted to add, I'm growing several different tomato plants several different ways on my balcony and the five gallon bucket is blowing away the competition so far.

I have a rooftop herb and vegetable garden that is doing quite well (the tomatoes are huge!). I don't do anything special - just use potting soil (ground soil that is rich in clay messes with water drainage in pots), prune, water sufficiently... basic stuff really. All that to say you can definitely do it. Just make sure to adjust for the likely increased heat/sun and wind on your roof.

The comments so far seem to say: yes, you can grow veggies and herbs on the roof. Agreed.

But LEA seems to be asking whether she can move her existing, thriving garden. She could try transplanting them in pots, but I think that after moving them at this time in the growing season the plants will never be the same. It will definitely be a big jolt to them. But you might as well try, what do you have to lose?

I agree with Jon B. It probably will be a big jolt to your plants, but if the alternative is leaving them behind, its worth it to try. That said, I grew lots of happy vegetables on my roof in Williamsburg. Unlike most of the flowers, the tomatoes seemed to love all that unrelenting sun. Good luck!

Getting advice from a community is a great idea, and Art is right - you growgirl.com and the forums are a great community and resource. Also the forums at Gardenweb. Everyone is very helpful, you will be amazed at the thorough and careful advice.

Since you are in the city I would also recommend that you go and speak with Trina Pilonero from Silver Heights Farm at her Union Square GreenMarket booth on Saturdays. No one knows more about tomatos than Trina. And she grows so many incredible varieties herself, she could possibly even advise you based on your tomato varieties. I bet you anything she will have the right advice.

My two cents: I have more experience eating tomatos than growing them :) - and we never had to transplant any that we grew on my family's plot. If I had to I would make sure to dig gently and outside the root zone a bit, trying not to disturb the roots. It's important to not expose the roots to air and to keep them wet and get them to their destination ASAP. It would help to have some mixture of fertilizer/peat in the transplant area and make sure the plant stays sufficently watered and sheltered from the direct sun until any signs of transplant shock have passed.

I am interested in Art's plastic bucket observation because in nurseries heat is used to encourage root growth. It is possible that the plastic bucket takes the sun in better and keeps the soil heated which is helping the roots grow. So possibly the buckets would be an ample and good container solution for both transporting and growing your plants on the roof. Keep us updated, Art!

Ah ha! Makes sense Matt. I can tell that the soil is quite warm in there. I'll definitely keep you posted on its growth.

I'm also using a 5 gallon bucket as a compost bucket and I don't snap the lid down all the way. There is a lot of heat in there too and everything is breaking down pretty quickly. I haven't used any beneficial bacteria to jump start it either, just a few scoops of potting soil every now and then to cover the accumulation.

Ah Lea, You have set out a challenge for yourself. Farmer's daughter, adroit gardener here these are my suggestions and certainly not guaranteed but may give a reasonable chance for success. Transplanting now is a bad idea BUT to increase your odds of success I'd do the following.
1) Have your receiving bucket sitting next to your plant
2) Prune your tomato plant back by about 50%, seriously!! cut it back but be sure to keep a decent number of leaves to aid in recovery
3) When you dig your plant with the largest root ball you can manage place it immediately into your bucket. Gently pack it in to avoid crushing and further damaging roots.
4) Give it a drink then give it a big drink when you get to your rooftop.
5) DO NOT start over watering at this point, just keep the soil reasonably moist.
6) hope for the best. Tomatoes are heavy feeders so if it survives for a week or so begin to give a dilute mixture of whatever fertilizer you use. Use low nitrogen fertilizer like a 13-13-13 or something like that. Too much nitrogen causes over production of foliage rather than fruit and you want the fruits. This will cause your tomato crop to be delayed but I think there is still a chance for success.
Good luck!