If you haven't already, it's time to cut back your tomatoes. By now they're likely
growing out the top of the cages and all the way back down to the ground again, making such a mess that you hardly know where one stops and another begins. They stopped setting fruit over a month ago, you've picked all the ones set before that, and you're getting tired of looking at them. Hornworms are more plentiful than fruit, especially the BIG ones that scream at you when you grab them, and you're probably noticing the beginnings of a spider mite infestation. Wouldn't it be great to just wipe the slate clean and start over?
Well, go ahead then. Just cut off the tops and there ya' go. That's all there is to it. Really.
Some people pull up their plants and replant this time of year, but I think that's such a waste. You've spent months growing a big healthy rootball, so why pull all that up and replace it with a baby that will have to grow it all back? Why not leave the rootball, and just get rid of the raggedy part? That's what I do, and it works wonderfully.
Sometimes, they'll try to regrow from the base themselves, but those sprouts won't get very far if they're shaded by the old growth. This time of year, the vines are so long and leggy that half of the plant's energy is taken up pushing water and nutrients through yards of stem just to get to the few leaves left on the ends. It's like the plant knows that, so is trying to deal with it by regrowing from new. Removing all the old top helps it do that.
If you want details, here they are: all you have to do is cut about a foot up from the ground, right above a node, preferably one with a little sprout already. Remove all the foliage, throw down some more fertilizer, and top that with a bit of compost. Watch the watering - without leaves, the plants won't need as much water now, so don't overwater.
That's all there is to it! Really. If you get it done now, they'll have plenty of time to regrow their tops in time to set more fruit when it cools off again. So get out there and do it! It looks so much better when you're done.