By looking at your photo's, the salt build up in your soil is causing this. See the white stuff on top of your soil that is what that is, and it is what is causing the plants to do that & could kill them. If you can repot them using a new soil, and maybe distilled water that could save them providing there is no root damage when transplanting.

Hi Shawn,

I am not certain that salt buildup is not the problem, but let's look at this a little deeper...

The first thing I would do is try to rule things out.

- Do you have other seedlings of the same species that are not having this problem, or is it all of them? If only some, what differences are there?
- Have you done anything different? A subtle change in watering, fertilizer, type of soil?
- What sun exposure do they have?

If you are having this issue with so many different species, the first thing I would do is to change everything that could be a concern. Firstly, re-pot them into new soil in different pots. Before reusing those, wash them thoroughly with a bleach solution. Do not fertilize them for a while except perhaps a slow release type, or a very weak balanced solution. The only thing I would recommend is Superthrive and/or a B1 solution.

Good luck! Let me know how it goes...

Eric

I'd question salt build up as the cause as well. It usually takes a while to get a build up from salts and it's usually worse with lower quality fertilizers like Miracle Grow. Soil should be flushed with clean water periodically to wash out the salts. I can't imagine that you've been fertilizing the seedlings, at least not much. Did you use old soil? I agree with Eric about Superthrive or B1 which will promote development of a strong root system. Pro-tekt by Dyna Gro is also a good product that you might consider using.

Thanks to all for the suggestions! Super helpful! I will try a combination of them.

Eric, it is a number of species, including decaloba, passi, etc. I did try some new peat pots and coconut husk pots, but no changes in watering or fertilization, and they have northern exposure for indirect light. Karyn, this is new soil and you are right, I had not fertilized them yet when this all started happening.

They are quite small for how long it has been since they germinated. I'm thinking it was something about the pots or soil--whether salt, mold, or poor nutrient balance, I'm really not sure. I had a system that worked before, I shouldn't have changed it!

shawn