I have a rubbermaid tub with four 23W cool white (5000K) fluorescent bulbs in it that I use for seedlings and small veg plants. I ran out of room in it so set up an LED fixture in a closet with four 15W 5000K LED bulbs.
The plants in the closet are clones of the seedlings in the rubbermaid. They’re in the same room, same medium (coco) and fed the exact same food (megacrop at ~800ppm). The original seedlings in the rubbermaid are all totally healthy and happy despite being stuck in solo cups for weeks now. The clones in the LED room all have a lighter colour and just look generally unhappy. What the heck??
Here’s the rubbermaid. All original seed plants that have been topped a few times. All growing happily and nice green color:
Here are 2 jungle spice plants. Left is the seedling mother that lives in the rubbermaid, and right is the clone from the LED closet. Again, they are in identical mediums and fed the exact same food:
When I first set up the LED closet I had the lights over a foot away just to be safe, then I moved them to about 5-6", and now have them at about 8". They’ve been doing this the whole time in there so I doubt it’s light burn but who knows?
I found this about what may be happening? It looks like a M deficiency…But this is just MY opinion, of course…
Here’s what someone said about his experience…
“Great observation. Working with LEDs I’ve noticed a lot of this. Under LEDs my plants seem to enjoy more cal-mag (magnesium to be exact as I’ve only ever had mag def under LEDs). Yes HPS seems to take bloom boosters best, because under other lighting I have often burned my plants a bit when introducing a booster. Under CMH I’ve had maybe the healthiest plants. T5’s as well, and flowered a damn nice plant under cfl’s before as well and required the least amount of food. Not any science behind what I say. Just sharing my observations.”
These are underwatered. Too dry and its prob throwing ph out causing your striping. One needs clean flush water other needs balance base. But both need liquid.
That particular one is unerwatered but I just watered it lol. They’re all in solo cups and the ones in the tub don’t sag at all so I assume I’m watering properly. Also, why the yellow color?
That’s interesting. The only thing I could figure is it’s gotta be something to do with the intensity/spectrum of the lights or something like that…so strange
Magnesium deficiencies begin in the middle of the plant while working upwards due to magnesium being mobile in the plant. But when it appears like a mag deficiency in the top working downwards its due to salt buildup and pH swings. Coco is best kept moist at all times. Let it dry out enough with a heavy salt buildup and your gonna have a quick lock out most times not…
Looking at the photos, the soil looks looks dry. Plants that big in solo cups, I’d expect to be watering pretty much every day. Myself, I’d be tempted to hit 'em with some Muskie and see if that doesn’t green them back up some. Muskie won’t burn, so giving them a shot won’t hurt.
Have you looked at the colour spectrum of those LED’s? If they are a real narrow band, perhaps your plants are looking for a bit more red. With 15w lamps, you should have no issue being within 6" of the plant tops.
@XxPeacePipexX Never thought of salt buildup, I’ll try flushing them and then rewetting with nutes. I still wonder why the ones in the tub look fine though? They’re way older and have been on the same feed/watering schedule this whole time.
@ITokealot thanks, I moved it up a bit tonight to see if it helps
@Schmokey whats muskie? I threw an 8W warm white bulb in with the cool whites a while ago to see if it would help, no noticeable difference so far…
Saw the same under my ledmo 50 watt flood 6500k.
Just added a 120 watt full spectrum to my tent, now that I have some growth and am dropping the light by 1/2 hr every other day. 16:30 light/7:30 dark atm.
LED light has a bleaching effect, at least that’s what I’m seeing in the single temp ranges.
Throw a 2700k Sylvania bulb in that closet, I think you’ll see a difference.
I’ve always struggled around week 3 for Coco/LED. I’ve found you have to be very careful with nutrients, light intensity, watering schedule and especially vpd. Remember that your LED closet will probably be colder because your lights emit less heat. This can definitely impact your vpd.
If you have trouble finding Muskie, you should be able to get some “FISH” brand organic fish emulsion at Canadian Tire. It says “no smell” on the bottle, which is mostly true unless you spill it on yourself. Luckily Crocs are easy to spray off.
@ReikoX unfortunately my closet isn’t that tall but I’ve got it at max height now. I also added a warm white LED to the fixture. What’s weird is the plants in the rubbermaid grow into touching the bulbs regularly and they don’t really seem to mind at all.
