Hi all- urban farmer here and having an unusual challenge with some seedlings/cotyledons turning yellow. My main concern are the bok choy (1st pic) which are sharing a tray with some spinach seedlings (2nd photo). Usually my brassicas have no issues but this is the second sowing that is being weird (had to toss broccoli seedlings with weird coloration). Here’s also a photo of the bok choy tray next to broccoli & collards for comparison (3rd pic).
The true leaves for the bok choy look green atm but i would like to correct any issues before they become affected (4th pic).
For informations sake I used a soil starting blend of coconut coir, worm castings/compost, perlite, & vermiculite.
Does anyone have thoughts on if this is a disease, nutrient, or watering issue? Going to start eliminating & checking factors.
Would appreciate any and all thoughts!
by apples4ever
6 Comments
How much compost/worm castings is in there? I bet it’s not much. Either the soil is very poor in nutrients or you are overwatering hard and roots can’t uptake nutrients properly.
To met it looks like the soil is over watered.
Soil is too wet
If your brassicas are doing ok, it might be a soil temp thing. Brassicas love cool bok choy can handle cool but likes 70s. What are your temps?
Looks like a lack of nutrients in the soil combined with a bit of over watering. The visual cues for me are the damp looking soil and the yellow leaves. The fact that the new growth is still green, points to a lack of calcium in particular.
Calcium is water soluble and plants will steal it from old growth to power the new leaves if it’s all getting washed away or wasn’t present enough to begin with. It’s probably needing some nitrogen too, since a shortage of that will also cause yellowing.
I would avoid watering on a schedule when they are this small and only water when the trays feel light. I know it’s hard – watering is one of the few ways to love on our baby plants but it’s easy to over do it.
Once they dry out a bit, try giving them some diluted liquid fertilizer and see how they respond. Good luck and happy planting!
Edited to add – what’s your soil made of? It looks like pure coco coir, which unless it’s amended and buffered properly is known to bind with calcium, so I think that’s your main problem.
Oops, I see you mentioned your soil mix but since I can’t see any perlite, I have a feeling your ratios are off.
Nutrients or lack of nutrients shouldn’t affect the cotyledons. Seedlings that small are still getting almost all of their nutrients from the cotyledons themselves, so it’s unusual to see them be affected by anything environmental in the first place. It could be too much water, as others said. Plants turning yellow from too much water is common gardening advice. If, for example, when you water them, the soil blocks are sitting in water for a very long time instead of saturating them briefly and then removing all excess water, that could have created an overly wet situation. It is not obvious from any of your photos that there’s something wrong with the setup, except for the visual cue of the plants being yellow. Whatever it is, I wouldn’t toss the seedlings until they actually wilt or stop growing. These can probably be saved.