If you're among the avid gardeners who start their tomatoes indoors, you probably have some tall thin seedlings about now that look as if they'd fall over if nothing more than a fruit fly flew by too fast!
But - and I know it's counter intuitive - if you pinch off your seedlings, they'll slow top growth long enough to focus on broadening and strengthening the stem, and on setting really solid roots. What you do is wait until the seedlings are sprouting their fourth REAL leaf (so, not counting the very first two mini-leafs they put out just after sprouting). Pinch off this fourth leaf to just above the stem of the third.
(In the above photo, these seedlings are growing their third leaf, but not the fourth quite yet).
You'll think you've ruined your plants - nothing happens for a solid week - but then you'll find that your plants resume growing, much strengthened by their mini-sabbatical!
Once they resume growth after the hiatus, they will probably need repotting in 4-inch pots. Plant them deep into the soil - right up to just below the first leaf. They'll grow roots off the buried stem - a unique talent of theirs - and again, they'll grow to be much sturdier above ground, and incredibly well-supplied with nutrients from the roots below ground.
FYI: We've published other posts on sprouting tomatoes.