I don't see any lights. Are there any? Also, you refer to heat, but you didn't tell us what temps these seedlings were subjected to. 90F should be fine for tomatoes and peppers IF the soil is kept moist. What is "normal soil"? You mean, just scraped up off the ground? In that case, added fertilizer is probably a wise move, but if the organic content is low, the stuff could be just turning into cement. At least the top looks sort of friable.

My apologies for the vagueness. So I have an LED grow light that draws about 100 W (Picture below). It’s about 10 inches above the plants, I hold my hand underneath it to make sure it’s not too hot, But the fan moves the air underneath it anyways. I stuck one of my home temp sensors next to the seedlings. It’s 5:50 AM right now and it’s reading 81°. I’ll update this post in about 7-8 hours and let you know what it’s reading when the sun is full blast.

So about the soil… I started out using seed starting mix from Espoma, but now it’s a conglomeration of used raised bed mix and compost (50/50 ish) that’s been sifted through a 1/4“ mesh. The problem is in these small seeds start trays the soil does actually turn into very crusty almost like cement. It does break apart when I rub it with my finger, but I feel like in videos that I watch it just seems so much more soft. I bottom water by letting it sit in water for about 20 minutes, but it never reaches the top, so maybe I need to pack down the top part more… starting from now I just bought a cheap bag of Burpee seed starting mix and will just be relying on a synthetic fertilizer after about 10 days from germination. It’s just hard to tell what the top of the soil should look like when it dries letting me know it’s time to water.

The compost I’m using is a whole separate issue and will probably be a separate post, but in short I bought it from a landscape company and it still had some black recognizable wood chips in it. I’ve been sifting out the wood chips, but maybe there’s still some finer not fully composted wood that’s gotten through the filter. I’ll post a picture of the unsifted compost below, and I’ll update this post with a handful of sifted compost once I get home from work today.

That all sounds sensible, but you might lower the grow light down so that it almost touches the seedlings. Bottom watering is chancey. The soil surface should be noticeably moist, at least for germination. If the soil mix is reasonably sterile, damping off shouldn't be a problem. At least dig down and make sure the soil is mostly moist under the surface. Note that peppers grow much more slowly than tomatoes.

Ahh I see... yes in the past I haven't been sterilizing my seed mix and was getting a lot of damping off, fungus gnats, etc... Once I transplant all of these I plan on starting fresh with sterilized mix. I think with a more peat based and finer mix the water will wick up all the way.

I actually was concerned the grow light was too close. So as long as it doesn't burn my hand (even if it gets relatively hot) it's ok to drop it super close?

Also, its 10am and the grow area is 87 degrees.

LED grow lights are never too close. Yours gets relatively hot? Again, high temps are just fine for tomatoes and peppers. They like it!

Well now that you mention it… only about the first inch or two is actually hot, I’ve just been erring on the side of caution lol. Good to know about the pepper seedling growth being slower. Today when I looked at them I actually saw the true leaves grow much more, they may not actually be stunted. Thanks for the sanity checks! I’ll probably toss an update on here later on when I start using more seed friendly soil. I think I have a good understanding now… thanks!

The tall ones, I guess, are tomatoes? They look very leggy as if they aren't getting enough light. I assume the light was left on for at least 12-18 hours a day? A lamp like that, 10 inches up, shouldn't be that bad.

Exactly... This grow light is no joke. I have no idea what is going on with these, and many other plants (spinach, lettuce, prairie flowers) either stunt or get leggy. The light is on a constant 18hr schedule. Like I said, I did drench them before I left for a week, and they shot up like that, but the leaves never increased in size. I'll post a picture of all 8 tomato plants after I got back that week and you can see they're all a bit similar, but those were the worst.

In my original photos above, you can also see those tiny plants off to the left, those have been that size since I planted these tomatoes...

Interesting note, the plants I planted into either growbags or pure compost (no-dig) garden are growing beautifully now... So I think I just need to get them into some higher quality soil. But it still does not make sense because I gave these leggy ones a roughly 3-3-3 water soluble fert a week ago.

P.S. The grow room max temp looks like its 91 degrees. It's 5pm and still that high. Still think that kind of temp isn't affecting them any?

Here are all the plants after the mass drench and week trip. Looking at it more closely, they're all pretty much in the same state. Maybe too much fert?

spinach; tomato; tomato

tomato; tomato; basil cutting

tomato; tomato; tomato

______ tomato; spinach

mint cutting; basil cutting

Same setup at different angle

I think that your potting mix has a lot to answer for. A lot of people have complained that their seedlings are stunted this year, and when they potted them up into something different, they have taken off.

For next season, since you are really worried about damping off, try starting your seedlings in Promix HP. (It's really dry and I have to water my seedlings every day, but I like to keep an eye on them). HP has no nutrients, so it's necessary to pot up into a mix with added nutrients or to add fertilizer. I use Promix for Herbs and Veggies which i's organic.

I agree with Labradors. The appearance of your potting soil looks questionable. I have been using ProMix BX which also contains mycorrhizae and have had very good results.

Again, tomatoes THRIVE in heat (as do peppers and eggplant - other solanaceae). No worries about 90F. In fact, if the temps are only in the 70sF, they'll grow slowly. I'm assuming that this is intended as a fall crop, because tomatoes won't pollinate in high temps. But for fall crops, most people do their starts in July or August. In Texas, spring starts need to be in January.

Timing is another thing I’m learning for sure. I’ve been Willy-nilly planting seeds to see if I can get anything to grow (essentially setting myself up for failure). Thankyou for the heads up about July-August for starts!

Yes I’m getting more and more convinced that the soil is causing much of this. Next planting I’m going to sterilize a bag of burpee seed starting mix and stop using old sun dried/depleted soil. I thought I could just fertilize the problem away, but clearly there is more going on…

Thank you all for the replies!

Timing is critical for tomatoes in a hot climate. You need to plant out early enough that they will mature and flower before temps get too high to pollinate. It's a real race. If you do that, April/May is peak pollination time, leading to harvest in June/July. This year, we had a spring heat wave - hottest May on record, and my tomatoes largely didn't set fruit at all. Bummer. For a fall crop, you need to plant out when the heat is intense, so plant survival is a challenge. Then it's a race to get fruit ripened before a frost. In this respect, fall is actually a bit shorter than spring, making fall crops somewhat harder. But my melons are all going bananas, so it's not all bad.

FWIW, I usually rely on Jiffy seed starting mix and can't recall ever having any problems. Once seeds sprout, they go outside in the sun.

A month or so back would still be way too late to start tomatoes here. Night time temps need to be below 75F for fruit to set. I go by our state university ag extension site for planting dates in my area.

Haha yes the ONE plant that’s doing well is this cantelope we planted as a semi joke. It’s taking up 1/3 of the garden and has two grapefruit sized monsters on it.

So I’m hoping the Houston weather will pull through for me, we usually don’t even start to get cold until the end of October. But like you said I should probably wait till at least July to start seedlings. It’s going to be hot here for a longggg time.

That's sounds like me. Many years ago, I started growing melons, and it happened because I planted canteloupe as sort of a joke. Whoa! It took off like crazy. Do be aware that beasties of all kinds love canteloupe, especially when it starts to smell ripe.