Answer: First of all, congratulations on your green thumb! Are these the plants you started from seed?? If so, I'm impressed!
Tomatoes have two different growth habits: determinate and indeterminate. Determinate plants grow to a specific size, then produce a single main crop; indeterminate plants continue to grow and produce all season long. Determinate types usually do not need to be supported; indeterminate types will eventually need supports because they continue to grow all season long (and can get quite out of hand!) If you are growing indeterminate tomatoes you'll want to find a way to shore them up now or by the end of August they will have taken over most of your yard. They are probably much too large to place wire tomato cages over them (which is something I would recommend next time - when the plants are very small), so you may end up having to support them with a make-shift trellis of some sort. I'd drive stakes into the ground (metal or wood, not bamboo) and string some twine between the stakes, then tie the heaviest stems and branches to the twine to help hold them upright. Use a soft material (old nylons, strips of cotton tee-shirts, etc.) so the ties won't cut into the stems and branches.
Hope you have a bountiful harvest!
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