leaves turning yellow, and withering / shrivle

[corbmonster]

My first time to attempt to grow, anything really. Most of my Tomato plants leaves are yellowing and withering / shriving. I'm not sure why, maybe too much water? Or too much sun. They get sun all day long. And it's still cool here in TX. Highs are about 70. Growth medium is 1.5 part bag compost (home depot), 1 part moonure, and 1 part pearlite. I wanted to make 1 part everything plus 1 part coir, but It didn't come in before the plants out grew the starter and I had to trans plant.
The image did not work in the preview. Here is the link https://imgur.com/a/uWr3h Also included is a pic of a squash plant that is yellowing / dying on the outside of the leaf. Oh, I had added a few pellets of miracle grow slow release / pot when I transplanted them a few weeks ago. But they started acting weird a few days after I started keeping them out side all the time this week.

[imafan26]

I think your mix is too heavy and too wet.

Manure is used like fertilizer, you don't need a lot of it. I don't add manure to potting mix because it is very high in salts and depending on the source can burn the plants. Compost and moisture control potting mixes will hold a lot of water.

I use a much drier mix. One part peat moss, One part perlite, a couple of handfuls of vermicast per 5 gallons of mix when I have it, and a couple of tablespoons of osmocote per 5 gallon bucket. This mix drains and dries quickly. In the rainy season I may only have to water every 2-3 days, but in the dry season I would water daily. I tend to over water so this works best for me. Vermicast usually does not burn.

The other consideration is the size of your pots and make sure there are plenty of drain holes.

I usually start seedlings in 3-4 inch pots (community pots). After the true leaves emerge, I transfer them to larger pots. Some things will have a third step to the final pot or the ground.

Seeds contain all the nutrients the plant needs to get through the first few weeks. Too much fertilizer or moisture in the soil can cause the seeds to fail to germinate or dampen off from being too wet.

It is hard when you over pot to be able to keep the seedlings moist while not keeping the soil too wet. When the plants are small they cannot drink up all the excess moisture in a big pot and the mix will sour and the seedlings will dampen off.

If you did not harden the seedlings off properly they may burn.

[rainbowgardener]

You didn't say until I looked at the pictures that these are tiny baby seedlings. Imafan is right, the mix you made is not good for seed starting, way too heavy, dense, moisture holding. I wouldn't put manure in a seed starting mix at all, though if it is well aged, it is good for your garden. If you got your coco coir, you can make that 1:1:1 mix of compost, coir, perlite.

And then be careful how you water. Watering is the trickiest part of starting plants from seed. You can't let them dry out, but it is easy to over water. I like bottom watering - put all your pots in trays and then just put a little bit of water in the bottom of the tray and let the soil wick it up.

Full sun is fine for these plants if they are used to it. If you started them indoors, then they have to be hardened off to full sun gradually. But if the sun were the problem, they would be more likely to be sun burned (pale and crisped) than yellowed; I don't think that is the problem.

[corbmonster]

Hey everyone, thanks for your replies, I really appreciate it. I started them in a green house starter in bagged starter / potting mix. Then transferred when the roots were too big (they roots were growing out of the starter tray and into the water pan. So the manure and nutrients I added were just too much, and I should have waited for my coir? Well darn... What should I do at this point? Re-pot? Start new seeds? Do nothing? I am in the process of building a wood growing box for the plants, if they survive. So they will be re-potted eventually.

[rainbowgardener]

I would re-pot in a looser, more free draining mix.