HELP! Browning tips and edges on young plant

[bumblepuppy]

Hello everyone. I would very much appreciate some helpful suggestions from experienced growers regarding the condition of my plant. The problem will be obvious from the pic: the browning of the leaf tips and serrated edges. This is my first grow in coco coir. The strain is Liberty Haze and is three weeks old. I am using a LED grow light equipped with 5watt diodes which, at the moment is positioned 27 inches above the top leaves. I am feeding with Canna Coco, (supplemented with a Cal/Mag solution) according to Canna’s on-line ‘light feeding’ recommendations. I have so far given the plant only two applications of this nutrient with a no-nutrient watering in between. From looking on the site, it seems that my plant is suffering nutrient burn, light burn, or potassium deficiency (?) I think I can discount the possibility of light burn due to the excessive height of the light. The temp. in the room with lights on (18 hours) varies between 81–86 F (27-30 C). (I have a White Widow auto sharing the space, growing in soil, whose leaves are totally unmarked). I had not noticed any evidence of browning before the second application of nutrient – perhaps this is just a coincidence. This brings me to another question: The Canna guidelines suggest the use of a specified quantity of nutrient according to container size. In my case, 32ml (A+B) for a 3 gal (14 litre) container. But I need only 1 gal (5 litres) of water for about 30% runoff so I cut back on the nutrient proportionally for that 5 litres. I do not understand why the Canna guide does not simply state mls per litre of water since coco coir is a ‘run to waste’ system regardless of container size. Can anyone clarify this for me please? My last grow (my first indoors) was a failure -- trying to tend to three plants of varying sizes and of unidentifiable bag-seed strains. They were predated by mites that I could not control and deformed by ‘claw-leaf’. I hope the wisdom of other growers can help me to overcome a similar disaster occurring this time around. Cheers.

[DrPhoton]

Thanks for providing various information on your grow, many do not provide all the information which ultimately just slows down the progress for help.
This does look like it could be potassium deficiency. Light damage can present similar symptoms but light damage usually shows up as bleaching rather than brown damage. So unlikely. For potassium deficiency it could be either a PH imbalance which prevents the uptake of potassium or a insufficient supply of the nutrient from its soil or fertilizer. But this seems less likely.
So check PH and check what the NPK ratio is for your fertilizer.

[tyler_ hobbyist]

Ur in gd hands man lots of people here are very amazing growers to me it seems that u have potasium def because of the brown around the sides of the leaves. I don't grow coco but I'm experienced in soil. I haven't used that brand of nutes but that's what it seems like to me. Check ur ph and re adjust ur ph and nutes if need be. If u ever got questions feel free to pm me

[bumblepuppy]

Thanks guys for your replies. You both seem to agree in your assessment. So its not nutrient burn, then? I've just had a look at the Canna containers for the NPK ratio which are: Part A: 5-0-1-0, Part B: 1-2-2-1. -- (don't ask me what the fourth figure in each represents!) but discovered that the directions on the bottle recommend a concentration of about twice what I have been using so this possibly lends support to the deficiency advice. [Could a plant of only three weeks already be showing signs of nutrient deficiency?] I have been going by the Canna on-line guide that, for some reason, seems to vary from the bottle instructions. Perhaps the on-line guide is for a true hydro system? Confusing! Also, I've not wanted to overdo the nute-ing as cautioned against on the GWE pages. So... should I water now with the bumped-up nutrient - while the coir is still damp - or should I wait a couple of days when it actually needs moisture? (Re the pH, I have been careful to get that within recommended range.)

[tyler_ hobbyist]

Soil and hydro will always or should alwasy have different nutrient useage charts as soil will have nutes already readaly avalabile for 2-4weeks and still have traces of nutes for a while. Where hydro has no nutes just maybe trace minerals depending on ur water. U can get def in coco/hydro at anytime because it's less forgiveing than soil. I would wait because u dnt wanna over water her and sufficate her roots and stress her out

[DrPhoton]

How easy it would be for a plant to have deficiencys would likely depend on how enriched the medium is to begin with. If it is quite inert, which you can have with pure coco mediums, would reduce the ability for the soil to buffer between feedings and increase the potential for nutrient deficiencys. This is why in hydroponics more time and care is required for nutrient control and monitoring.
Iv done some analyzing of quite a few popular fertilizers and i found that most manufacturers play it safe with their concentration levels. The recommended dosages are usually lower compared to when manual mixtures are made with EC levels.
If memory serves me, good starter fertilizers quite often add extra potassium because saturation levels drop quickly with young plants.

Its very importent that you let the medium dry out between watering. Saturated medium can drive out oxygen and cause death to roots, causing slowed growth and shock.
Continue on with the recommended doses and see how you get on, if you like you can try a potassium fertilizer such as potash (potassium sulphate) which is highly soluble to the plant. Just start 1/4 strength and perhaps level off at half strength until symptoms improve.

Good luck.

[bumblepuppy]

Thanks for that Dano. Might check out the Potassium fertilizer. I'm a bit nervous about introducing another component to the mix, though. I failed to mention that I forgot to add the Cal/Mag additive with the last watering. So there's another deficit in the health of the plant, perhaps. Interesting that you claim manufacturers are conservative in their recommended dosages. I've gained the impression, possibly incorrectly, that they err on the up side to maximise profits(?).

[oldjarhead100]

her'es something else if you go to age old web site you can look at their feed schedule it is different than whats printed on the bottle so I think whats on the bottle is if its used by itself if used with other nute it needs to be reduced . here an example on the bottle of fish and seaweed it says 1 tbs per gallon but on the feed schedule it says 1tsp per gallon

[oldjarhead100]

hey Bumblepuppy welcome looks like you got good advice , I would like to add a couple of things coco has no nutrients in it zero you need to add everything .Your base nute provide a lot of nutes but not all you need to find a nute with Micro nutes. I use ageold organics Microsynergy if you go to ageoldorganics.com you can compare whats in it to the nutes you use. Now that being said Liberty Haze in my experience does not like alot of nutes,when ever I've grown it with other strains I've nute burned it. So I would suggest doing a watering with micro nute then if problem clears up yaa if not back off a little . When you water they like to be soaked then dry out the knuckle test is ok in small pots but it won't give you accurate readings down deep so I would suggest a water/ph meter under 20 bucks the ph wont be accurate but the water part will I let mine get to dry on the scale then water. lastly the ph for coco is 5.5 to 6.5 so I try to keep it at 6

[bumblepuppy]

Thanks jarhead for your comments. Micronutrients eh? Your observation that LH is sensitive to over-feeding has me wondering if that's the problem rather than a deficiency. But, anyway, I'll boost the nutrient next feed to bottle directions which is about twice what I have been using based on Canna's on-line schedule (that I don't really understand in terms of container size to nut concentration). And, maybe trial with the micros. Cheers.