Yellowing Leaf Edges

Interesting problem with my bathtub grow. Yellowing leaf edges middle and upper part of plant (newer growth). I filled out the questionnaire below with my info IN CAPITALS and have attached pictures. Any thoughts?


Thanks in advance!


1. Are you growing from seed or clones? CLONES
2. How old are your plants? 1 MONTH (USING AS MOTHERS)
3. How tall are your plants? 14 INCHES
4. What type of hydro system are you using? COCO HAND WATER 3x PER WEEK DRAIN TO WASTE
5. What brand/type of nutrients are you using? HOUSE AND GARDEN PLUS CAL MAG(HEAVY DOSE) AND SILICA
6. What is the Ph of your nutrient solution? 5.8
7. What is the PPM/EC of your tap water? 60 (R/O WATER)
8. What is the PPM/EC of your nutrient solution? 1400 (this includes 2tsp per gallon cal/mag. If not used deficiency shows)
9. What is the temperature of your nutrient solution? 60 - 70
10. Does your PPM/EC show a rise or fall when you do your daily PPM check? SAME
11. Does your pH show a rise or fall when you do your daily check? RISE
12. Do you foliar feed or spray your plants with anything? YES, ONCE EVERY TWO WEEKS WITH MAGIC GREEN.
13. What kind of lights do you use and how many watts combined? (HPS, MH, fluorescent, halogen, incandescent "plant lights") 8 BULB FLORESCENT
14. How close are your lights to the plants? 2-4 INCHES LEFT MY ROOMATE IN CHARGE HE MAY HAVE ALLOWED TO GET VERY CLOSE.
15. What size is your grow space in square feet? 8 SQ/FT (BATHTUB)
16. What is the temperature and humidity in your grow space? HOUSE KEPT AT 68-70. PROBABLY 75-80 UNDER LIGHT.
17. Have you noticed any insect activity in your grow space? MINIMAL
18. How much experience do you have growing? NEW IN COCO

IMO too much calcium is locking N up there.. N and Mg get confused often but the best way to tell them apart is that a nitrogen deficiency starts around the tips and works its way to the back of the leaves, where a magnesium deficiency will cover the entire outer part of the leave and make the entire leaves yellow leaving the veins to stay green.

While you need the Mg too you're supplementing too much Ca, maybe you're nutes have more enough and you're creating an unbalance.. so well... argg I hate to recommend Epsom Salts, but that's what you need, 2 tsp per gallon and lower the dosage of calmag to 5ml.. ditching the RO system would be sweet too, it's a complete waste of money.

Could be a couple of things, 1- its too hot ,you say i think its 75-80, get a peak memory thermometer in there. 2- drop the cal/mag additive ,too much cal and mg lock out other nutes, just use the standard veg nutes.They are going well in size but cool it down and stop the snake oils ,the new growth will be a lot greener.

*BUDS said:

Could be a couple of things, 1- its too hot ,you say i think its 75-80, get a peak memory thermometer in there. 2- drop the cal/mag additive ,too much cal and mg lock out other nutes, just use the standard veg nutes.They are going well in size but cool it down and stop the snake oils ,the new growth will be a lot greener.

Click to expand...

I ask because I trust your opinion, you think 75-80 is too hot? I run 80 all the time with no problems and rh at 60%. Just curious your thoughts, no disrespect

Looks like either a zinc or iron deficiency. I am leaning more towards zinc. Coco is known for potassium build up. And too much potassium can inhibit zinc uptake. Heres a link that should help you zero in on the exact cause:
http://www.greenmanspage.com/guides/plant_abuse.html

Wouldnt worry too much about excess calcium being the case. Too much calcium causes problems with magnesium and potassium uptake.........

Thanks for all the input. Here is my plan of attack.

1. Install thermometer & fan
2. Keep lights 4" above plants minimum
3. Flush (should take care of any potassium build up, imbalance, etc)
4. New soup with reduced cal/mag (half dose vs 2x dose), epson salts @ 2tbs per gallon. PH to 5.8 every watering.

I'll let you know how things turn out. Thanks again for all the input!!

Dude I meant Tsp! I'm not used to that way of measuring.. Mg and Ca are interrelated so there should be a good balance

Haven't fed yet since I flushed last night. I'll change epson salt dose (I thought 10 tbs in my 5 gallon bucket seemed a lil' high). Thanks again for your help. I'll send some recovery pic's (hopefully!).

Just want to throw my opinion out there, I think it looks like classic MG all the way, either due to straight deficiency or PH. I do notice some burning at the tips as well however, so the flush proabably wasn't a bad idea. In my regular feeding schedule I use plain water every 3rd feeding and let 15% run through to clear excess salts. I would do that every watering if it wasn't such a hassle to clean up. I personally treat RO water with Cal/Mg so even if i'm just plain watering, I'm dosing those. This is exactly what my most common deficiency looks like, aside from N during early growth, which would look similar, but with out the green veins. I just assume my plant is getting the correct balance of Ca and Mg since I always dose them together.