Hey there DGC. Love the show. Its has really taught me a lot. Been growing for about 6 years and still learn a little something new every time i tune in. So i have a grow room with 7 4ft by 8ft tables. 6 of the tables are under 2 1000w hps lights and one of the tables is under 2 Growers Choice Roi680s LED. The table under the LEDs is showing a lot of interveinal chlorosis and some purpling leaf tips and ridges. Mostly close to the top of the plant. Which is why i’m wondering if the plants under the LED lighta require different nutrition than the others under HPS. I’m using Dyna-gro nutes and every 3rd watering is a silica,enzyme, and recharge only. pH is right around 6.0 every watering and ppm are about 1300 to 1400. Temp is 76° and humidity is 60%. The plants are at day 32 currently. Any advice would be greatly appreciated
This is an interesting question, I hope it gets picked for the show.
My first experience with LED was 1 grow ago and I came from 600w HID. My LED is more of a 1000w replacement, so there’s some other variables in my grow, but I had to start adding magnesium to maintain a luscious green.
Have you checked leaf temperature? Possibly needing a warmer room for efficient photosynthesis and solubility of some nutrients.
It seems a lot of people need extra calmag when switching to LEDs, but I think it all starts with temperature and spectrum. Interesting topic, I don’t really have the answer, but I wonder the same things you are.
Looking like a molybdenum issue which usually is caused by low ph. Minimal amounts needed as it’s a micronutrient. Also could go along the lines of the intervenal chlorosis if its a magnesium issue. Ive noticed with led that you see deficiencies faster as the light really pushes out the photons and your plant will need to have a proper meal available in order to run at that high level. Also plant temperature seems to facilitate the amount of nutrients it can move throughout the plant. Upping your room temperature into the low 80s [82-84f] will be beneficial as well as checking the ph of your medium.
so my only concern with upping the room temp is that most of the room 6 out of 7 tables are HPS lighting so i dont want to adjust the room to suit the LEDs and negatively effect the hps tables. Also ive never heard of molybdenum lol, but im gonna look it up now. Appreciate the feedback. I hope the crew pics the topic up. I think its pretty interesting
How far off canopy are the LEDs? How do the leaves deeper in the canopy look? I
The lights are about 12in off the canopy and the lower growth looks a Normal lush green
I have not checked the leaf temperature. I definitely will and check back in. I was considering a magnesium deficiency but im noticing it firat on the top of the plant. If it was a mag issue wouldn’t it start from the bottom up since magnesium is a mobile nutrient? (Learned that from the show by the way. Tha ks guru 😉)
this is interesting. especially the Mag def with LEDs. Ive been using white LEDs with some far red for a while and always notice i get a mag deficiency even when i use cal mag and my base nutes have cal mag as well. Im in coco and started adding Bud factor X (Mag) and the leaves turn more green in a few days.
Yes you are right, it is a mobile element. Low soil temperature will reduce mag uptake and higher photosynthetic activity at the tops along with lower temperatures can inhibit mobility from the older leaves. I’ll admit that’s half science half theory, but in my experience having the room warmer with LEDs, more specifically having the leaves warmer, will encourage photosynthesis.
I’m not seeing a mag deficiency in your plants, but definitely taking a look at the soil pH can point you in the right direction.
Id try and rig up a curtain with plastic and try and get the led tables temps up a bit. maybe feed some ballast heat from the HID in that part of the room. -create a micro climate.
could even try with part of the led table first, just to see if it helps.
To briefly summarize it has to do to the infrared spectrum that’s lacking in the led. This will effect leaf temp and transpiration. So your vapor pressure deficit of a healthy plant narrows.
So simply put, what work for you with your HID is less forgiving with the led. – raise humidity of room, mist entire plant with tap water. Do this for your next grow.
Try some sm-90 if available. They took it off the market for adding salicylic acid off label. You can make your own however, this stuff will aid in transpiration in a non favorable VPD environment.
i did a feeding of Silica, enzyme, recharge, and mag pro out of the dyna-gro line and it seems to be helping
We in dirt or coco here? Plenty have left a bunch of feedback and I’m only going to chime in because I have the same led’s only time I had an issue was when I grew DWC. In soil since and no issue like this. So my thought is if you are in coco, you could have a similar situation to DWC whereas you need to provide all your nutrition. I know mag is mobile and cal isn’t so before anyone says “don’t use a cal-mag mixed solution if you don’t need them both” I am aware if that and am just using this post as an example and to provide maybe another possible culprit. When in DWC I chased it for weeks and for me the fix was the 5-10ml recomended per gallon needed to be doubled under the led. AGAIN….In no till organic soil now with microbes and have not had a repeat incident so for me I chalked it up to DWC and learning what each strain needs nutrition wise. I have never grown under hps so I can’t weigh in there but will tell you they soaked up cal and or mag when I used a grow style (DWC) where all the nutrition was on the grower to provide.
More food for thought than anything.