I think that your best bet would be to take some big-ish cuttings now. Once rooted, you can set them deeply into your 3-gallon container and you'll be all set. Of course you can also cut the mother plant back and see how she does, but usually fresh cuttings end up being the better choice.

It's difficult to manage a tall tomato plant "gone wild". You could look into compact varieties that do well in 3 gallon containers for the future. I grow a few, using a small cage that fits into the pot.

Linda

I agree with Linda on the management program ^^^ And do the cuttings right away of course to be ready. Usually indoor plants don't get good light when they get too big and they still need to be hardened off since the protection behind glass or walls with lights does not season them properly. Because of that reason alone I would start over and harden off over the last week with the new clone.

You certainly can guillotine the main stem and train the suckers. If I recall this topping method was the main method used in France well over 100 years ago, before determinates were introduced to Tomatolandia from Florida.

Good luck!

PC

If you have a very large window, perhaps sliding doors for your balcony (if that's where the sun exposure is,) you can lay the plant down sideways and the lower branches (suckers) will begin to share the primary growth characteristics of the main stem. You can then take your cuttings, or even root through layering.

Thx for all the suggestions. Another option perhaps - can I simply cut about a foot-length of the top of the main stem, and use that as a new clone ? Planting it deep. Or does it have to be a sucker ?

Yes. You can do that! Roots will form along the stem.

Linda