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Trouble with Kale seedlings #741468

Asked March 29, 2021, 5:31 PM EDT

I am trying to troubleshoot why my Kale seedlings are having trouble. I seem to repeatedly lose them just as they are trying to grow their first set of true leaves. Their seed leaves shrivel and die just as the true leaves try to emerge. I've probably lost nearly 30 kale seedlings although my buttercrunch lettuce is doing very well and so far my broccoli looks promising (still no true leaves yet). My possible thoughts: Although the picture will look like the potting soil is super saturated, that was only a recent problem and I lost many seedlings during much better soil conditions. I had put some water in the overflow dish to try to raise the local humidity and wound up watering from the bottom. That has been rectified. I tried raising my grow light height in case the light was too intense. Perhaps this is still the problem but I don't know if one can find clues to the light being too intense. Currently the timer has the light on for 17 hours and off for 7 hours. I'm not sure quite how to identify damping and what to do to rectify this possible problem. relative humidity is about 40% and temp is around 70. I think these are probably fine? I included a picture of a kale seedling which looks like it is just about to go the way of its siblings. I also included a picture

Lane County Oregon

Expert Response

The pictures do not give as much info as needed. The setup seems to be a bit odd with the colored lights. Seedlings do not need light until they emerge. Once there are true leaves lights should be 4-6" above the plant tops, but if you are using intense lights, such as halides or incandescent, then that would be too close.

Damping off is a common disease of seedlings and usually the stem pinches shut and the seedlings collapse. It is related to moisture and especially to airflow and to using an improper medium.

If you have more info on these facets, feel free to reply with more information.

Patricia Patterson Replied March 30, 2021, 9:27 PM EDT

The colored lights are common LED growing lights which concentrate on the blue and red spectrum without the green.  They probably qualify as intense, though I do not have the means to measure their PAR.  As I mentioned, my lettuce is thriving under these conditions and the broccoli seems to be doing fine in early stages.  Only the Kale is having trouble.

Can we deduce anything from the seedling picture?  I see one of the seed leaves has shriveled and died while the new true leaf is browning at the tip (and on its way to dying).  The stem seems vigorous.  Is this pattern inconsistent with damping off?

The Question Asker Replied March 31, 2021, 11:46 AM EDT

Thank you for your response. No, the symptoms on the kale do not fit damping off. LED lights do not produce much heat, so that is not the problem. The kale is quite pale in color which usually indicates a root problem or a lack of fertilizer. Do you use the same seedling mix for all your plants? What is the green under the kale, if that is growing plants, the kale are being outcompeted. Kale is normally quite strong as a seedling so this is a strange problem. Something is interfering with the roots would be my guess, but what? Waterlogged soil would bother the kale the most over the lettuce which is mostly water anyway. I wish I had a better answer for you. I would start over on the kale with different soil and NO garden soil at this point. Good luck.

Patricia Patterson Replied March 31, 2021, 11:58 AM EDT

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