But I like tomatoes (despite not eating them raw unless they're in salsa), and so I always want them in the garden, but I don't necessarily like nursing them along. But I'm also cheap so I won't buy any new plants, nor will I start seed. So what is one to do? Take cuttings of course!
Tomato plants are actually vines and they will root along the vine where it touches ground. You could just let your tomato plants flop all over the place (which is apparently what my grandma used to do), or you can stake them to take up less space (which is what most people do - I guess that's the difference between living on a farm and not). Occasionally, especially during wetter weather, you'll see bumps along the stem - these bumps are not some weird Tomato STD, but are actually little aborted root nodules - when you see these, your tomato is trying to root.
If you want any other proof that tomatoes are vines that root easily, my friend accidentally decapitated a tomato plant as she was planting it in the garden - she, being an engineer and up for a grand science experiment, planted both the bottom half (with roots and a few leaves) and the top half (the growing tip) in the garden next to each other to see what would happen. The top part ended up being the best tomato she had in her garden that year.
So! Tomato Propagation. If your tomato plant needs a do-over, you can take some cuttings and plant those (it's also a good way to save tomatoes over the winter if you've got a greenhouse).
Step 1: Find your victim (I mean donor!).
Step 2: Cut off about 4-6" of a growing tip of the vine - you can't just cut off a leaf and expect it to work, you need some actual stem and a growing tip.
Step 3: Cut the stem at an angle and remove the bottom leaves leaving only the top two leaves.
Step 4: Hold your pruners at an angle and drag it along the bottom inch or two of the stem. Supposedly this 'bruising' helps with rooting.
Step 5: This is the point where you would dip the cut end in rooting hormone if you have it/want it; but I've also known tomatoes to take root without the hormone - but the rooting hormone does help.
Step 6: Poke a hole in the dirt (whether that's in the garden, or in a 4" pot). If you're using a pot, I'd recommend using cutting/seed starting mix as opposed to regular garden soil.
Step 7: Put your cutting in the hole and press the soil around the stem.
Step 8: Water well.
Step 9: Label your plant.
Step 10: Water daily - it would also be smart to provide shade so the poor little thing isn't having to contend with trying to grow roots and fend off the death star.
Step 11: Wait a few weeks (I noticed mine had roots after about 2 weeks; but I also use the rooting hormone)
Step 12: Plant!
Now then, by the time I'm getting around to writing this (August), it's already too late to really be planting tomatoes - the last weekend in July is generally the last recommended date for planting tomato transplants, BUT, now you'll know for next year.