Certified GKH Gardening Expert
Yes, they can. Just leave plenty of room for your tomato plants to grow since some varieties can get fairly large. Many people say not to plant them together (though I always have) and the reasoning behind this is that they're from the same plant family, which makes them susceptible to the same pests/diseases and, thus, may increase the chances of problems. That said, others feel it helps to groups members of the same family together. I would, however, recommend rotating the crops every other year or so (even every 3 yrs) to another location to reduce pest or disease problems in the future.