First, you omit to tell us which herbs you are growing.

However, I can tell you that a leggy seedlings is crying out for more sun, and for a larger pot. They ought to have been transplanted some time ago, by the sound of things.

The general rule of thumb for transplanting is to plant no deeper than the existing root ball. Dig a hole at least twice as wide and twice as deep as the root ball, then fill it in so the level of the dirty bit is the same as it was in the original pot, then fill in. This process ensures that any new roots don't have to struggle through hard-as-rock soil to spread out.

An exception to this rule is tomatoes, which can be buried deeper than the root ball.

Here is a link that might be useful: picture of a root ball

That's what I was afraid of. I shall transplant them today into bigger pots...at the root ball level. Like I said, they grew a LOT faster than I expected them to. All the seed packets said "6 to 8 weeks before last expected frost." And they SURELY didn't grow this fast other years when I planted them straight into the garden! They're the culinary herbs, by the way: oregano, rosemary, thyme, dill, three kinds of basil, etc...

Thanks for the info and they WILL be transplanted today. I hope they survive. I'm guessing it's too late to start over.

Believe it or not, they didn't grow that FAST....it's just that their cells are so elongated that they appear to be taller, longer. Each plant cell has had to flatten itself out so to expose more surface area to what light is available. That makes the stems flimsy, too long, and the leaves may look larger (because they are flatter), too. Does that make sense?

Most living plant cells have chlorophyll, the food factories of every plant. Sunlight (or light in the correct wave lengths) is the energy source that runs the factories. Because sun is required, plant cells will do everything needed to access as much as they need. If a plant is getting enough light, the cells will be compact and dense, making a stem nice and stocky and stong.

Another factor in making seedlings too leggy is heat. Seeds need heat in order to germinate, but prefer cool (even coldish) air temperatures once the germination process is completed.

I don't think transplanting them to larger container will help one single bit, at least not without a big increase in light. But at this point, those stems are already a permanent part of the structure. They aren't going to fatten up no matter what you do.

I'm guessing that you may need to resort to store bought plants this year and plan for a good supplemental lighting system for next season.

I am NOT arguing with you. Heaven knows, just about anyone short of my 2-year-old grand-daughter probably knows more about transplanting than I do, but the directions on the jiffy greenhouse said to keep the seedlings OUT of direct sunlight? Should I just start over? Apparently we have a ridiculously long growing season here, so could I start them outdoors in the garden after 4/4 (which the local extension promises me is the last possible frost date?)

The directions given are fairly vague weren't very specific. What they mean is that you shouldn't put seedlings out in the fierce sunlight, because they are babies which need a lot more TLC than adults. However, the seeds still need light to germinate, and you've provided enough for that purpose.

Now they're not seeds any more, they a bit more grown up, and they need more sunlight. The process of gradually introducing more and more sunlight and exposure to less protected conditions is called 'hardening-off'. For a few hours each day, move your transplanted babies to a somewhat sunner spot, where there is some protection from wind, and gradually increase the time they spend in full sun.

Seedlings are like children. They want and need to grow. And they will do it. Trouble is, if the roots can't grow and spread, then for as long as they can manage it, they'll put their energy into growing the above-ground bits. There's a limit, however. Once a pot is root-bound, the plant can no longer access nutrients and water, and eventually those roots which choke themselves to death - along with the rest of the plant. This is why transplanting is so necessary.

You can always chop off or pinch out the top one or two rows of leaves. Chopping off a plant's head (unlike human heads!) will encourage side-shoots, and you should end up with a lush, short-but-fat plant - assuming the root system is healthy and not squashed, and assuming the plant is in an environment it likes, of course. All the plants you have like it hot and sunny for at least 6 and preferably 8 or more hours per day.

Short but fat is good. Thank you!