I have to admit I keep coming make to this thread; the idea keeps niggling at my brain for some seed I want to start.

You could do this two ways:
1. just fill the filter with soil and let the baby grow. Transplant filter and all when plant puts on some size.

2. carefully lift the sprout, using a dampened pencil tip, to a newly prepared cell pack and grow under lights. If there are any leaves they should be above the soil line.... if not, well then, below soil level.

I guess what I was asking, is, would it better to transplant from filter to cell pack before the leaves develop, or after. I was waiting until after, just so I could be sure the seedling was off to a good start. I was afraid if I did so with just the root poking out and no leaves yet, that that particular seed may not sprout leaves. But would it be better for the seedling to do so earlier...better developed root system perhaps?

Todd In Philly

If the seed's big enough to grab with tweezers, even tho' there aren't leaves yet, I'd go ahead and move it. With tiny seeds (which rosemary really isn't), I might leave it on the filter paper and then cut the paper into bits, each containing a couple of seedlings, and plant the bits intact. My main concern with planting on the (whole) intact filter is that in my (limited) experience, the paper doesn't degrade terribly fast, and I'd want to have lots of open soil around it so the roots had someplace to go. (If you've sowed a whole packet on one filter, you also have a LOT of seedlings there, so if you leave them together, you'll have a tangled mess and regret it when you do come to transplant finally.)

Either way (with or without paper bits), best to transplant as soon as you have a root. Doing it later just gives you more root hairs and root branching that can be destroyed by the transplant process. Trust me, a seed which has sprouted a root will, in its own good time, sprout leaves as well, providing you don't accidentally break off the little seed at the top of the root. Just keep the environment good and humid, to avoid stuck seed coats (common on tomatoes, haven't had much problem with other plants).

Don't use tweezers, it's too easy to squeeze too hard. Use something with a dampened tip to move the sprouts by lifting rather than "picking". If you must "pick" then only pick up by a leaf.

I do agree that the coffee filter should be torn before transplanting. I did like the idea about cutting up the filter and planting the pieces.

As to your specific question: I'd wait until there are the first leaves then move to a sterile soil. But you don't have to... just make sure the roots go down and the rest heads toward the light. I would imagine that is a mute point since the sprout surely has leaflets by now.

Cut the filter apart and get these tiny guys into a soiless mix before they get much bigger. No reason to wait for leaves, or even true leaves. There is nothing to sustain them at the moment and since the root has sprouted it will get more fragile instead of sturdier. If it was in soil I would wait until the leaves developed- but not in a coffee filter.