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Yellow tips - nute burn or too much light?

R

roperman

New member
In week 4 or 5 into flower and things have been going fairly well. First coco grow in a 4 x 4 tent, using GH nutes, growing one Northern Lights and one LSD. Been going higher on pH now that they're in flower, around 6.2. I have been using Nebula's half strength grow schedule for coco. Lately, I'm seeing the slightest amount of yellow tips on new growth and most upper leaves, new or old. Might be nute burn but I'm not sure. Does this look like light burn? I'm using Luminus COB's for lights... grow has been going well, lights are between 18 and 20 inches.

Hoping that this doesn't get worse.
 

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Looks like minor nute burn to me. Super minor, if it were me I would do my next feed and up them a bit more. I like the plants to tell me their limits when feeding. Burnt tips tell me that.

Good looking plants.
 
Agree with UrbZ and you... very minor nute pre-burn. But, with respect to Urbz, I would probably not recommend upping the nutes... How often do you water your Coco? How frequently are you applying nutes?
 
Morning roperman, I'm thinking your cobs, might be a little close, you might want to raise them up a couple of inches, looks like some top leaves, might be starting to canoe a little bit.
 
Raised the COB's two inches just in case.

In veg I was watering every 4 or 5 days but was told that you should water more often in coco. So I went to every day, alternating calmag water and nutes. The humidity went bonkers in the tent lately, 60 to 70% so I cut that back to every other day. That seemed to lower the humidity, so I think I'll stick to every other day watering. I've got 5 gallon pots. I put on 1.5 gallons of nutes or water with a drip irrigator, but I'm thinking of bumping that to 2 gallons so I get more runnoff. I have two plants - one plant's runoff is about 2 quarts, and the other about one quart. Does this sound about right? I'm going to bump up the volume so I get more runnoff on each.

So here's a noob coco question. Nebula says to use half strength nutes every other watering. When I went to daily alternating watering is when I started getting the yellow tips. Can I switch to one quarter strength nutes for every watering instead of alternating between water and half strength nutes? I'm thinking that might avoid the nute burn, if that's what it is.

Thanks for everyone's feedback.
 
Humidity is an issue with daily watering of Coco, no doubt.
Watering amounts seem pretty high, so seems like the Coco must be getting pretty dry. How much Perlite do you have mixed with it?
I use 5 gallons of Coco in 7 gallon pots and I do not give them more than 1-1.25 quarts apiece to get decent run-off with daily watering.
When I get burn, I usually do the opposite of what you are suggesting... I will double up on CalMag only and then resume every other watering. Flushing the media with water without nutes is important to prevent build-up. If you dilute the nutes, I still would flush at least every 4th watering.
 
2 parts coco to 1 part perlite. If I wait two days I could probably add a gallon of water with no run-off.

If I use 1/4 strength nutes and use two gallons per plant, wouldn't that be enough run-off to avoid salt buildup? I will be getting close to 1 gallon run-off with 2 gallons of water.
 
I guess I am just not sure what the benefit is of doing it as you're suggesting. I doubt it will cause serious problems and you can certainly try different methods. Seems like a lot of water and excessive run-off.
 
I guess I should have been more clear by no means was I saying jump your nutes up to 3/4 strength or anything. But to me If I had a plant that was showing no nute burn at the levels I was feeding especially at 1/2 or 1/4 strength I personally feel like the plant could handle a bit more, like 1 ml more each of my nutes. You are already at half strength 1 more ml isnt going to hurt but it will help.... I would still follow the 1/2 doses of the recommended nutes each feed for each week, plus my 1 ML extra. This is the scale that most people use to tell if they are over feeding no burn can handle more food, a lot of burn back it way off, just a little burn equals just right.

Basically if you don't get a little bit of nute burn you will never know what the plant can handle.
 
I'm guessing that giving 1/4 strength nutes every watering may avoid the nute burn, if that's what I've got. Much lower exposure to N every time, but maybe enough cumulative N for the plant. I really have no idea really, just thinking about strategies to avoid the burn. I guess I can do the experiment and learn from the experience.
 
I think it is cumulative, so I am not sure that it will be result in a different level of N reaching the plants, but absolutely experiment if you want.
As UrbZ suggests, the level of "nute burn" that you have is very minor and does not constitute a problem. I think we only differ in that he would like to see even more burn before backing off and I think you already see what you need to know where the limit is. In any event, you are comfortably in a safe range.
 
Most of the reason behind the "feed, water" schedule is for salt build up. The water helps flush salts out of the pots. It's also helpful to use something like a flush additive to break down salts on your water days.
 
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