Past 2 years I have begun seeds in a sealed self rain / water container.
I transplanted into pots. 24 hours later they are withering. Do I cover only the root with dirt or all the way to the green plant?
What am I doing wrong?

Assuming you are transplanting the sprouts at the cotyledon stage. Cotyledons must be above the ground but the rest can be below soil level for roots to develop.
I use a mister to water in after transplant. That gives a very light jet of water into the earth to ensure that there is soil contact with the root and no chance of drying out while the plant is getting over transplant stress. I don't always water in immediately, depending on the dampness of the potting mix. If you see wilting after transplant, gentle watering is the first thing to do.

I don't start my seeds without dirt, so there may be other considerations for seedlings sprouted in water alone, then the shock of being transplanted into earth.

Thank you! The seeds were begun in soil, inside a plastic sealed milk jug. They were beautiful. Once I trans planted outside their rain forest, they didn't like it.

NonnaGrandma wrote: ↑Thu Apr 24, 2025 10:39 am Once I trans planted outside their rain forest, they didn't like it.

Maybe the shock of the rapid change in temperature and humidity?

And it appears yer new here; introduce yerslef and location in the Introductions up top: viewforum.php?f=3

The Gotch

Seedlings grown indoors need to be gradually « hardened off » to night temperatures, wind, UV from direct sunlight, etc. If you feel the leaves, the ones that have been kept indoors or sheltered are much softer and thinner.

Those mini greenhouses are pretty much the same thing as an indoor environment except for the high humidity. Google « hardening off » for more information.

@NonnaGrandma I usually will wait until the plants have their first true leaves before I try to move them into their own pots. I find that if I move them before that the stems are just too small and are easily bruised. You may want to wait a few more days before you try to separate them just to give the plants some time to get more strength.

NonnaGrandma wrote: ↑Thu Apr 24, 2025 9:41 am Past 2 years I have begun seeds in a sealed self rain / water container.
I transplanted into pots. 24 hours later they are withering. Do I cover only the root with dirt or all the way to the green plant?
What am I doing wrong?

I am unfamiliar with the way you are starting seeds- exactly what is a sealed self rain/water container? Like a terrarium? Like winter sowing in a gallon jug with potting mix?

Started in small cells mostly with multiple seeds, with starting mix, and preferably outside when possible to make sure they are always acclimatized to the world. Not in hard direct sun as this is Texas, but with good light and normal wind and having to work a bit to push up out of the soil mix.

When I separate/ transplant my very young tomato seedlings, at the first true leaf usually ( unless I am running behind !), I poke the baby into the dry potting mix pretty much up to the leaves, then carefully top water for the first and only time, then make sure they are firmed in well. After that, it is always bottom watered unless rain falls on them.

Between being in the open air when possible and having to work to grow up out of the soil, I feel this gives me hardier and stronger transplants without hardening off shock. I also use a higher nitrogen fertilizer very diluted in the water about once a week or ten days as the plants are putting on growth rapidly.

@Danny I believe the method she was starting seeds is called 'winter sowing'.

https://www.epicgardening.com/winter-sowing-beginners/

@NonnaGrandma I usually transplant over 100 seedlings, mostly tomato and pepper. And when I pot them up, I do it in the shade and keep them out of the light, usually overnight, before putting them back under the lights. And as others have mentioned, you definitely would want to harden them off to gradually get used to your outside growing conditions when they get big enough.

NonnaGrandma wrote: ↑Thu Apr 24, 2025 10:39 am Thank you! The seeds were begun in soil, inside a plastic sealed milk jug. They were beautiful. Once I trans planted outside their rain forest, they didn't like it.

Rainforest is a great place to start seeds. Sprouts just love it.
As others mentioned, hardening off or giving the plants time to adjust gradually to changes is the way to go.
So in the case of the sealed jug, I would start by opening it up to ambient air for starters, for a day or two or even longer, so they get used to it not being a rainforest. They should be okay to transplant safely when they've gotten used to drier air.
I also start mine on a heat mat in a clamshell with some dirt, rainforest style, but I have to remove them from the heat and open up the clamshell as soon as they shuck their seed coats. So they soon find out, we're not in the tropics.
Sometimes I've had quite large plants in the greenhouse, which got moved outdoors and lost all or nearly all their leaves out of shock at the different environment. So it's not only at the seedling stage, they seem to structure their leaves differently for the conditions they're in. Outdoor plants can have very different looking leaves from their same kind in a more humid and sheltered place.
I hope your plants recover from the shock.