you may try this link fo pruning

Here is a link that might be useful: How to Prune Tomatoes

Thanks! I've been faithfully taking off the suckers to keep the plants down to
a more manageable number of vines, but I'm also concerned about how the vines
themselves don't show any sign of slowing down in growth. There's only so much
dirt in those pots!

fraxinus - Those plants are just beginning to grow!!! You're going to need larger pots or a deep trough for that area. Vermicompost makes great mulch as if feeds as well as controls watering needs. Only fertilize when you really think it's necessary, too much will actually weaken the plants. Later on, when they've really become cumbersome you can prune the growing tips and just let the fruit develop. Quite the challenge. Best of luck.

The idea of repotting them (especially doing so without getting dirt all over my office) is an intimidating prospect. What would be signs that they need repotting?

What would be signs that they need repotting?

****

The size of the plants now, in June, as opposed to the size pots they're in now.

What varieties are you growing? That would be good info to know for folks here in terms of what the ultimate size of the plants could be. Meaning, are they indeterminate or determinate?

Carolyn

They're both indeterminates. Do you mean that I should repot them now? I put another couple of both types in the ground where I live, but we've had a cool spring (especially nighttime lows), and none of them are more than a couple of feet high yet. But my office would make a decent greenhouse -- lots of direct sun with moderate highs and lows.

Figure the mass of the plant above ground as the same as the mass below ground. Tomato roots grow extensively when the opportunity presents itself. Oh, and lay down some newspaper before you repot and take your time. It's fun.

They're both indeterminates. Do you mean that I should repot them now?

For indeterminates those are not "huge" plants. As jbann said they are just starting to grow. ;) So no, they do not need pruning yet but yes, they do need to be in larger pots and now is the time to re-pot them. You won't be able to do it later without killing the plant.

Those plants, by nature, will be easily 6' tall. Growing in a container will keep them stunted a little. But if grown in a proper size container, carefully topped, and some of the lower level suckers left in place you'll get you a bushier plant that isn't quite as tall.

A fan that puts a breeze on the plant will aid in pollination. Fans as well as some hand-pollination are used in greenhouses.

Dave

As Dave says pruning suckers will give you a taller plant. If you want a bushy plant I would cap the top and not the suckers.

People often sucker plants to reduce them to a single terminal vine that they may want to climb up a post.

Also, and its been said, tomatoes are genernally not indoor plants although there are some very small determinates that may work well.

Greg