Purple Stems/Leaves - When to Fert

[mobiledynamics]

It's has 2 feedings of fert in my no fert potting medium.
Between that and or maybe dialing back the intensity of the LED lights - but glad to report that all the leaves are nice and green !

[Lukasrl]

I am playing around with LED's this year as well. I had the same issue as you with all of my tomatoes. Purple underside of leaves. I did fert but it didn't help. I think it may have something to do with the strength of the LED's. I have a 45 watt and a 300 watt. The tomatoes were under the 300 and I had it raised about 10-12 inches above. They were not growing much, in fact some of the leaves started to dry out even though the soil was moist (not wet). Now I am not sure if they just out grew the purple leaves or what I did next was the reason. I raised my 300 watt an extra 12 inches. Soon as I did that, the tomatoes really started thriving. Nice thick stems and root system. So many sights say put the LED just a few inches above them. I'm not so sure about that. I saw one video which demonstrated that too strong of an led light bombarded the plant in so much photons that it stunted the growth. Hope this helps, and I would not worry so much about the purple leaves in your seedlings.

[bower]

Oh, wow. Really helpful to hear about this, thanks!! Just googled "LED stunted growth" and found a lot of confirmation about that.
Example this manufacturer:
https://justledus.com/keeping-your-l...oper-distance/
" In most cases your plantation will be stunted if the light is hanging close.."
".. if you keep your light at an affixed height, the plants will reach a certain growth point, then grow wider and form more vegetation.."
That's what I thought about my bok choy - they stopped getting taller instead of growing up into the light...
I'm almost tempted to try stunting some of the large tomato seedlings now before they get leggy! Wonder if it has any long term effects

[Koala Doug]

Originally Posted by bower

I'm almost tempted to try stunting some of the large tomato seedlings now before they get leggy! Wonder if it has any long term effects

That would be quite interesting if you could temporarily arrest the vertical growth of the main stem and encourage side-shoot growth instead!

[mobiledynamics]

Vertical grown is happening for me. Stems are getting nice and thick. What is interesting is just the leaves/sides are much more bushier than *vertical*. Some of these go out 7-8 inches with about 10 leaves on them. I just eyeballed it and it's about a inch between each growth on the stem.

I am finding that with this sort of light, I'm needing more space / grow lamps as I have to ~open up the spaces more~ between each pot. more to give the leaves some room.