Like Collector, we've had problems with cages falling over. We came up with a simple solution, and for the past 3 years, we've used it with NO cages falling over. Our cages are short sections of wire fence bent into circular cages, but regular tomato cages will work the same way.
We hammer a T-post into the ground at the end of each row and every 3 or 4 plants along the row. Then we tie a rope at the top of the T-post, stretch it across the tops of the cages, and attach the rope to the top of the cages with cable ties.
The plants are pretty overgrown, but hopefully you can see what we've done. Our plants are spaced 3' apart, and the rows are 5' apart. As you can see, most of the plants are growing out of the tops of the cages, but none of them are falling over, because of the rope at the top. The T-post on the right is the end of a row, so we angled it out. You can see another T-post by the red shovel.
This was supposed to be a pic of our squash, but Zeus insisted on helping. You can see the tomatoes in the background.
You can see how overgrown everything is. The two rows on the right are almost touching, but none of the cages are even leaning.
It's important to install the cages, T-posts and rope when you plant the tomatoes, because it becomes difficult to do it once the plants have grown even a little bit. I like this method, because we no longer have to constantly tie them up with strips of old bed sheets or tee shirts as others have mentioned in this post. All we have to do is walk the aisles a couple of times a week and poke the plants back into the cages when they begin to escape.
