are you using a heat mat and covered dome?

I'm not using either of those. I tried to use one or two of the jump start heat maps but they didn't seem to make a difference as they generated very little heat. So is my main problem that it's too cold then? What covered dome and heat mats would you recommend? I think my trays are 22 x 11" so would need a big enough dome to cover those.

I have the same grow light and it works great. It looks like you have it way too high. Drop it to 2-3" from the seedlings.

Do not use a dome or heat mat. That is for germinating seeds not after they sprout. With extra heat they will germinate faster in the future. Using it now they will grow leggy and spindly. The dome can cause damping off.

Peppers are very slow growing and 3 weeks as cotyledons is not abnormal. Listen to this while you wait... https://m.youtube.com/watch?v=ErvgV4P6Fzc

Ok so sounds like my problem then is either the soil or the height of the light over the plants? My guess is the light is probably 8-12" above the plants right now, so sounds like they aren't getting enough light.

Lee, if you use the search feature on this site, you will get a lot of good information on seed starting. Most folks use a heat mat and clear plastic humidity cover until the seed germinate and then both are not necessary. Also, you need to provide some air movement like a small fan at this point for air circulation over the sprouts. Are you using any additional lights? Cheap florescent lights an inch or two above the sprouts will really help them grow to health plants and not get leggy and fall over. I don't know how you are watering but they are too dry. Try putting water in the tray and let them wick up for about 15 minutes and then dump the water. Good luck.

Menards sells a kit with tray dome and heat mat for $20-25. These are standard 1020 trays. I have 4 of these and start everything there then move to another area under lights. I have had them for several years and they warm up to 70-80 degrees under dome. I start 1 with tomatoes on March 12 and I have 2" tall tomatoes on March 16. I think this is a pretty good investment each are used for at least 5-10 times each season. after they germinate, I pull out the 1020 tray and replace with another for the next batch.

I am just watering over the top of the soil every few days with a small watering can. I thought that you don't want it too wet as the plants might die from lack of oxygen in the soil?

I do as you are doing Lee, I think your watering regime sounds fine. If they aren't wilting they aren't too dry IMHO. Peppers like to dry out a bit between waterings. Tomatoes not as much.

I don't think they are unhealthy, just lower the lights and be patient...

Keep in mind that seed starting mix has almost no nutritional value and when you pot them up you should use an enriched potting mix or provide fertilizer with the waterings.

Would Miracle gro work fine for the fertilizer?

Here was the description on the Burpee soil I bought....

Supplies food to natural microbes to ensure plant performance and health.

Full Description

Balanced planting mix is well-suited
for germinating seeds, transplanting young seedlings and sustaining
growth until garden planting time. Medium is formulated to provide
proper conditions of aeration, drainage and water retention for healthy
root and foliage development. Tomatoes thrive in this calcium-enriched
mix. 10 Qt Bag.

Lee, sounds good. Seed starting is a lot of fun and rewarding. You are getting some great advise. You will be just fine. Enjoy yourself.

Ok so that mix is enriched a bit. I have a bag of burpee seed starting mix myself (it is not the tomato one but it honestly looks the same, coir and perlite,) and the nutritional value is low. Mine is labeled for starting seeds not potting mix.

You can use MG but only once they are growing true leaves, and if they are not in potting mix already enriched with fertilizer or are showing a need for it. They are easily burned by fertilizer and most dilute it over what is recommended, you have to be careful with the MG. Over fertilizing seedlings to get them to grow is one of the first mistakes I made. :)

If you go to the seed starting forum there are a bunch of FAQs you can read for more info, and tons of info available on Google but it sounds like you already did your homework.

Is that the "grow from seed" forum? Sorry I am new here so didn't see the correct forum to post this on.

Yes that's the one. No problems posting here though.

By far the most common cause of slow or stunted growth in young seedlings is over-watering, overly wet growing medium. Different mediums absorb and drain differently so one has to learn the absorption and draining rate of their particular medium unless they are using one of the common ones others can advise on.

So given the unknowns of your medium the best way to approach this symptom is to cut back on the water and monitor them closely for a few days. Your cells are plenty big enough for you to stick your finger down into. If it feels damp and somewhat cool do not water. Never use the soil surface as the clue to water needs.

Keep in mind that seedlings are much more tolerant of under-watering than they are of over-watering.

Dave

That mix is mostly coir with lots of perlite. I am using a similar one. It drains well and does not hold water like peat IME.

So it's been a few days now and no real response from the tomato seedlings, they just seem stuck at the cotyledon stage and aren't putting out their first true leaves.

I was going to comment on the height of the light also, but someone else already did. Although you feel the heat mat isn't that warm, but it could be just the temperature for the seedlings to respond to.

Since it has been 2-4 weeks since you started the seedlings, if you have space or additional cells, you could start another round. You never know if the conditions 1 month ago, as well as not using all the equipment that you had for the germination process, could have altered the seedling growth in some way.

Actually, I don't know if the following idea would be recommended by others, but you could probably put another 1-2 seeds in the same trays. If the original seedlings continue on fine, then you can keep them. And if the new ones popping up become better, then you'll have confidence in your germination media and know that it was other conditions which affected the first seedlings.

At the same time, be aware that the water needs for the seeds and seedling might be different, so consider that plan only if you wanted to try it and didn't have additional trays or space.

What changes did you make in those few days?

Dave

I lowered the light from 6-12" above the plants to 2-3" above the plants. Added a bit more water than normal as well. These seedlings have now spent ~ 3 weeks at this height and stage of development with no material change.

Dave is not going to be happy to hear that :D (...that you increased the watering)

Lee, If I were you I would start over with a fresh bag of seed starting mix... a different brand. Last year I had the same problem with my melon seedlings and I decided it was the seed starting mix. The mix worked for the tomatoes I started four weeks prior to the melons but some bacteria or something must have gotten in or an existing bacteria had grown to an amount that retarded germination and growth in my melon seeds. It was weeks later until I realized the problem so I planted the melon seeds directly into my garden and they germinated and grew just fine.... But as far as watering and light, the other posters have given you great advice.

Lee, they look healthy. No evidence of over or under-watering. They are likely cold. Several of the tomato seedlings have a purple tinge to them which happens when they are cold. Pepper will totally sulk if they do not get the heat they want. If your house is set to 67 degrees it is dropping down to 65 at times and they will not appreciate that at all.

Yes I am having that problem with my seedlings in the burpee mix too. I think it is a terrible insulator and does not absorb warmth. Not good for solanaceous starts. I have got all my solanaceous starts and I want to pot them up just to keep them warmer. Anyone have any other ideas? I may try to fit them on the heater at night.

The grow light gives off very little heat as well.

Last year I had similar issues. Peppers just did not grow. And tomatoes with yellow green leaves. They stuck for more than three weeks. Once I changed to my regular soil mix, they started growing immediately in three days. I kinda think you are having same issues here.

Thanks everyone. I am going to do an experiment and switch some of my seedlings to Miracle Gro potting mix and see if they perk up.

How's it going? My pepper seedlings are turning purple in the burpee mix. I am going to pull them out of there tonight. The habs I started in it are very purple and stunted and the ones in the peat mix are doing well, although the germination was poor. I will not use it again. Idk if it is the coir or what. It is probably too late to start my peppers all over but I will plant a few backups. I am tempted to try and remove all the mix from the roots but I am unsure they will survive.

FYI, purple leaves on seedlings can be the result of phosphorous deficiency which is the result of overly-cool soil temperatures. Roots don't take up phosphorous efficiently when they are cold. This is well understood and documented. Might want to be sure your soil temperature is where you think it should be. In principle your soil might just be phosphorous deficient.

It is seed starting mix very low on nutrients, and they are cotyledons, the soil temperature is at least 65F

Thanks everyone! I switched the soil to Miracle Gro potting mix and the plants have taken off like wildfire. No more Burpee seed starting mix for me!

I can also confirm solanaceous crops will not grow in the Burpee mix. But if you use it just to start and pull them out right away it works out fine. I pulled out my later sowings as soon as they started looking sad and stunted, even roughing up the tiny roots removing 90% of the mix, and they took off like wildfire after transplanting and are growing faster than last year. Very happy with the Espoma mix I am now using.