Leaf Edges Starting To Turn Yellow

Where on the plant is it starting from? If its on the bottom moving up then its probably just hungry for some nutrients, more specifically nitrogen.

Don't do anything yet until you find out what the problem is. It's not a big deal right now so you'll be fine as long as you don't panic and do something drastic.

JWM2 said:

Where on the plant is it starting from? If its on the bottom moving up then its probably just hungry for some nutrients, more specifically nitrogen.

Don't do anything yet until you find out what the problem is. It's not a big deal right now so you'll be fine as long as you don't panic and do something drastic.

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Both are about half way up and about the same size: 2.5 inches across or so. You suggest I still wait? I was expecting not to need nutes, but I could be wrong. I have Canna Tera Vegga sitting around somewhere and also the organic blooming fert from the same company. I've not fertilised any of these plants yet. All four are the same age. The leaves are pretty dark green, so I suspect they don't need anything.

I should add that this is my 4th grow in pots in a tent and I know from the other three that I have a tendency to under-fert. Previously I had quite pale fan leaves that dropped off early, but I was content with the yields. This time the soil had extra nutrients and the plants are generally darker green and more vigorous then I've seen before. So that's good.

I wrote about these particular leaves because they're not turning pale homogenously, as I've seen before on under-fert plants, but the edges are turning pale.

Hi. I've an auto 5 weeks old too. Can I ask if yours has started to flower yet?? Mine still shows no sign. Your plant looks healthy to me :)

They have started, but it's early days. The Shiva is a little further than the three Northern Lights. One of the NL is a little further behind the other two.

fliege said:

They have started, but it's early days. The Shiva is a little further than the three Northern Lights. One of the NL is a little further behind the other two.

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Cheers.
I'm not sure why mine hasn't started. Was supposed to be one of the fastest autos. Hard being patient. First grow!

Looks like low K to me. Feed those girls a strong flowering feed. You have a little twist at the tip of your leaves, telling me you are low in Zn. Make sure kelp or something high in macros is in your feed as well.

I see why you say low K and we're at the start of flowering, so that is reasonable. Since I don't know for sure what I'm dealing with, I will start by giving the recommended quantity of my Canna Bio Flores and see what the results are. If it looks not good, I will flush.

Since I think I see the problem spreading, I will send some more photos. It's generally on smaller leaves.

Textbook low K. Yellowing leaf margins.

Thanks, @Bulldog420, can I ask then what is the protocol at this point? I've never had to deal with a deficiency like this before. Should I just give the recommended fertiliser dose and see what happens? The company says 4 ml/L 1 to 3 times a week (http://www.canna-uk.com/bio-flores). I water with about 1.2 L every other day, so I guess for at least the first week I should feed with each watering.

I can also tell you that the plant is stretching, which is consistent with low K. I've been watering 50/50 RO/tap water, which I read (https://www.growweedeasy.com/potassium-deficiency-cannabis) can be an issue that could cause this to happen. There was no very good reason for using it, so I will stop.

I looked at the link you gave me for the fertilizer, but I couldn't figure out the products you might have on hand. Can you tell me the NPK value the bottle states? You need to cut back slightly on the N, and push your P and K at this point. K especially.

I discovered that's a hydro fertilizer as it has a pH of 5.0. So I'll not use it. I have nothing on hand that's low N and higher P and K. So anything you happen to suggest would be great.

Then again, if indeed this is a problem caused by over-watering and use of 50/50 RO/tap water, it may resolve itself once I dial back the water and switch to 100% tap water.

I call this shade of green "painful green".This is not the normal,healthy green they should have in that stage,but much darker,look like plastic and the veins are almost like electric green.To me it means way too much N and who knows what locked/caused by that.Autos don't need too loaded soil and too much veg fertz…..It also hardens the flowering.

Agree with Ina. Push that P and K, back off the N.

If you use chemicals, Monopotassium phosphate works great here.

Organic, get some bone meal and kelp meal. Liquid for quick response.

"electric green" on dark green is a very clear description. I'm impressed you saw that from the photos: I only noticed it after going to the plants. I think the plants are looking healthier since I dialled back the water. I guess they'll make it, albeit with reduced yields. I'll learn to not use silly soil in future. :opps:

fliege said:

"electric green" on dark green is a very clear description. I'm impressed you saw that from the photos: I only noticed it after going to the plants. I think the plants are looking healthier since I dialled back the water. I guess they'll make it, albeit with reduced yields. I'll learn to not use silly soil in future. :opps:

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I have seen these shades and colors on my plants few times,also the real intoxication till the end:) Thats why I know when I see signs of N tox:D I was overdoing a lot with veg fertz before I know they don't need so much,especially the autos.The buds can't develop nice(especially the very tops,they suffer the most),the leaves starting to "claw"(depends on your other conditions symptoms may vary but the colors are always too dark and unusual,some spots and other lock outs/deficiencies can appear ).It is because most of the autos start flowering before they eat all of the N and it stays(especially when they are in containers,not directly in the ground) and makes troubles in flower.Generally,as far as I can see we all overdo with N more or less,it happens at least once or twice before you notice what's going on.....:)
Yours don't look so intoxicated(like mine was),it is the beginning of the poisoning and beginning of the flowering, may be if you wash them a little with water and stop everything that contains more N they will turn nice in the end .I think you still have the chance to repair that.I hope you wont have further problems!!! but if you do, have that on mind, because it can continue bothering them in flower(in many ways) even if you try to wash it from the soil some how.Compost can be a b....ch if you use too much in your soil mix:)It also retains water(so may be they can feel better if you dialed back the water a little like you said,you know your conditions better),sometimes too much for too long and it can be really "hot"on veg fertz mostly.And if you repeat the N with some other amendments.....