Seedlings dying. Too much light? Unsuitable soil? Help please.

My over 2 weeks old plants look terrible. The leaves are pale green, turning yellow and drying. Now they have started rolling and tips turning up.

I can't figure out why it's happening. The soil has some nutrition already in it from the supplier so maybe that's why? First week I had them under only incandescent 100W bulb and a few days ago I moved them under 250W HPS. Are they getting too much light maybe?

I appreciate any idea.

Pictures included

Incandescent has insufficient spectrum to grow plants. HPS is said to grow cannabis, but it's heavy on red and low on blue light, which makes it a good bloom bulb. Vegetative plants like some blue light, such as that from metal halide.

A couple things that I see.
1. those pots are too big. When starting seeds its good to start in solo cups and transplant to bigger container once they are established and growing well. Unless you are doing autos where it's supposed to be sprouted in same container it finishes in. It's hard to get watering right when the pot is so big with such a tiny plant, much easier to water a small plant in a small container.

2. The soil doesn't look like it has any perlite or anything for aeration. Looks wet and heavy, which isn't what you want. If you want to use that soil I would suggest adding a bunch of perlite to help with drainage.
Your soil could also be to hot for your young plant, depending on how much stuff is in your soil.

What soil are you using?
How often have you watered?
Are those autos?

If they’re getting a full blast from the new light, I’d think that’s a likely culprit. Way too much for a sprout. Can you turn down intensity? Move light further away? I typically set light at 20-30% when plants are this young, and slowly turn things up as they grow.

At this moment I only have the HPS and some big CFL. Do the CFL provide a better spectrum and I should swap them for the HPS?

At first I kept them in smaller pots and I put them into these bigger ones after two weeks.

Not sure about the exact type of soil. Something I bought in a garden centre. But there is no perlite, that's true. But they shouldn't look so unhelty, should they?

I water them around every 4 days.

They aren't autos.

The thing is, here in Australia I struggle to buy soil that wouldn't have any enhancing stuff already in it... . The manufacturers put fertilisers in it because that's what sells I guess.

Is a metal-halide lamp better for grow stage than HPS? I think I have one somewhere..

jimcz said:

Is a metal-halide lamp better for grow stage than HPS? I think I have one somewhere..

Click to expand...

Can you dim the light? Otherwise raise it way up imo.

HPS is fine and I grew solely under 250W when I began but far away because it is strong for a seedling. I'd have them under T5s or CFLs. They look nutrient burned to me. I think your beginning media is too hot for them. We have an Aussie grower's thread here you can ask about finding a more suitable seedling medium.