Tomatoes root all along their stems very readily, not just at the nodes as most plants do. That's why you can plant a too tall tomato several inches deep....or lay one on its side in a trench.

For planting purposes, it is always better (from the plant's point of view) to root plants in a solid medium, rather than water. Though it's rewarding to watch the new little roots growing, those are not the kind of roots that plants need to function normally in soil, and they will have to go through a rooting process once again once planted.

Water-borne roots work to take dissolved oxygen out of water. Soil roots have to support the plant, exchange gases (oxygen and CO2), and absorb water and dissolved elements.

You're absolutely correct, Rhizo, that water is not a good medium for growing cuttings. However, I had just intended for it to stay "fresh" for awhile to feed my manduca sexta. I had no idea it would root. Never tried it before.

A lot of people think it's okay to use water as a rooting medium, but those water roots are so delicate, and not inclined to transplant well, if at all.

I always use an equal ratio of perlite and peat moss to root my cuttings, and I always plant my tomatoes much deeper that they are in the pot.

Susan

Oh, I thought you asked if the tomatoes could be planted out to grow. ;-)

Aren't you lucky that tomato plants are so easy to keep alive and healthy for your caterpillars? Not too many plants are that adaptable.