Yellowing leaves, 6 weeks into flower

[josep90]

Any idea what can be problem. Now is 6 week of flowering. 1 week before that were still beautiful and dark green. But now they have begun to turn yellow slowly. I think I burned them a little with fertilizer, but I don't know why they started to turn yellow now. The previous grow the same thing has happened in the last 3 weeks.

I added plagron terra bloom 5ml/l, sugar royal 1ml/l, pk 13/14 1ml/l and green sensation 1ml/l. Maybe too much PK?

I used 1350w with CO2

 

[Mike Wright]

That's normal as the plant consumes the nutrients out of the leaves and focusses all its energy into bud production.

They look great! And welcome to 420 Magazine, we're stoked to have you on board the internet's best and friendliest cannabis resource site. For a real welcome tell us a little bit about yourself in our Introduce Yourself thread.

 

[SmokingWings]

1 week before that were still beautiful and dark green. But now they have begun to turn yellow slowly. I think I burned them a little with fertilizer, but I don't know why they started to turn yellow now. The previous grow the same thing has happened in the last 3 weeks.

The pots of soil are not large enough to supply everything the plant needs as fast as the plant needs. All that new growth since the start of flowering is demanding nutrients and if the plant cannot get it from the soil it will take it from the oldest and largest leaves. You would be surprised at the number of growers, especially new soil growers, who start to notice the yellowing when their plants have been flowering for only 2 weeks.

Maybe too much PK?

More like not enough Nitrogen (N) and Potassium (K). The plant needs the Nitrogen to keep all the new green growth healthy and it is surprising just how much there is in the growing tips that stretched like crazy for a couple weeks. And the Potassium is needed for overall plant health and that includes all the new growth.

Kind of hard to do anything about it now that the plant is 6 weeks into flowering even though there are 2 to 4 more weeks to go. You can try to boost the N and K and it might slow down the yellowing.

Best thing I have found to work for me is to start using the flowering fertilizers about 2 or 3 weeks before I am going to put the plant into the flowering tent and still maintain the growing fertilizers until the flowers start showing. From then on it is the flowering fertilizers with supplements of Nitrogen and Potassium.

 

[josep90]

I was watering today and measuring runoff and pH

Ph: 6.3 That's what I think is okay
Runoff: 3 EC That's probably a little too much

So i think i have nutrient burn?

​

 

[bluter]

I was watering today and measuring runoff and pH

Ph: 6.3 That's what I think is okay
Runoff: 3 EC That's probably a little too much

So i think i have nutrient burn?

​

what's your media and how often are you feeding ?

 

[josep90]

what's your media and how often are you feeding ?

40% soil 40% coco 20% perlite

now I watered every 3 days, and now need every 2 days.

pots: 18L

 

[Roy Growin]

Best thing I have found to work for me is to start using the flowering fertilizers about 2 or 3 weeks before I am going to put the plant into the flowering tent and still maintain the growing fertilizers until the flowers start showing. From then on it is the flowering fertilizers with supplements of Nitrogen and Potassium.

Seconded

 

[bluter]

40% soil 40% coco 20% perlite

now I watered every 3 days, and now need every 2 days.

pots: 18L

soil as in peat base ?
wondered if you were feeding often enough. that mix could be near daily.

 

[SmokingWings]

40% soil 40% coco 20% perlite

As @bluter brings up, what is the soil?

Is it something natural like compost or is it a bag of "potting soil mix"?

One reason that knowing about your 40% soil is that would be helpful to possible solutions to your problem. The thing is that 40% coco and 20% Perlite adds up to 60% of what the roots are in is an inert grow medium that supplies no nutrients for the plant. Yes, it will hold on to water or water & fertilizer mixed together for a day or two but it adds nothing by itself.

 

[Wastei]

Any idea what can be problem. Now is 6 week of flowering. 1 week before that were still beautiful and dark green. But now they have begun to turn yellow slowly. I think I burned them a little with fertilizer, but I don't know why they started to turn yellow now. The previous grow the same thing has happened in the last 3 weeks.

I added plagron terra bloom 5ml/l, sugar royal 1ml/l, pk 13/14 1ml/l and green sensation 1ml/l. Maybe too much PK?

I used 1350w with CO2

You're not off with the to much PK assessment. More nutrients are not better when you add minerals on top of a already optimal mineral ratio. You're crashing your pH and causing lockouts from mineral ratios and pH being way out of range. You've added two PK boosters on top off each other when you would have been better of without them?

Calcium, Phosphorus, and Magnesium falls out in containers if pH is lower than 5.5 in the medium. To much P will also lockout Ca and K. MPK(mono potassium phosphate)is really low in pH and you have that in both PK 13/14 and Green Sensation.

Way to much sauce in the mix! Go by the K.I.S.S mentality, keep it simple stupid! It's just a plant that needs a complete plant food from start to finish. You won't find out what the optimal is by listening and following advices from people that only completed a couple of growing cycles.

Hope that helps! Cheers!

 

[josep90]

As @bluter brings up, what is the soil?

Is it something natural like compost or is it a bag of "potting soil mix"?

One reason that knowing about your 40% soil is that would be helpful to possible solutions to your problem. The thing is that 40% coco and 20% Perlite adds up to 60% of what the roots are in is an inert grow medium that supplies no nutrients for the plant. Yes, it will hold on to water or water & fertilizer mixed together for a day or two but it adds nothing by itself.

bag of potting soil. Maybe try with 50% soil, 30% coco and 20% perlite?

 

[josep90]

You're not off with the to much PK assessment. More nutrients are not better when you add minerals on top of a already optimal mineral ratio. You're crashing your pH and causing lockouts from mineral ratios and pH being way out of range. You've added two PK boosters on top off each other when you would have been better of without them?

Calcium, Phosphorus, and Magnesium falls out in containers if pH is lower than 5.5 in the medium. To much P will also lockout Ca and K. MPK(mono potassium phosphate)is really low in pH and you have that in both PK 13/14 and Green Sensation.

Way to much sauce in the mix! Go by the K.I.S.S mentality, keep it simple stupid! It's just a plant that needs a complete plant food from start to finish. You won't find out what the optimal is by listening and following advices from people that only completed a couple of growing cycles.

Hope that helps! Cheers!

Then I would have tried without PK 13/14? Only green sensation?

 

[SmokingWings]

Is it something natural like compost or is it a bag of "potting soil mix"?

bag of potting soil. Maybe try with 50% soil, 30% coco and 20% perlite?

Most likely the bag of potting soil is 50% or less compost and something like 40% peat moss or coco coir and 10% Perlite. Once that potting soil is mixed in with the amendments you have it is very possible that your new mix is mostly peat moss or coco coir and Perlite. Neither the peat or coco will supply nutrients until they decompose which can take years. The Perlite is totally inert.

You should be able to buy a quality soil mix meant to work well with Cannabis plants the next time around. It might seem a bit pricey at first but can come out cheaper than buying the ingredients separately.

 

[josep90]

Most likely the bag of potting soil is 50% or less compost and something like 40% peat moss or coco coir and 10% Perlite. Once that potting soil is mixed in with the amendments you have it is very possible that your new mix is mostly peat moss or coco coir and Perlite. Neither the peat or coco will supply nutrients until they decompose which can take years. The Perlite is totally inert.

You should be able to buy a quality soil mix meant to work well with Cannabis plants the next time around. It might seem a bit pricey at first but can come out cheaper than buying the ingredients separately.

I looking now for use biobizz light mix, its this ok? Or better plagron light mix? I use then only soil? or mix with perlite or something else?

 

[SmokingWings]

I looking now for use biobizz light mix, its this ok? Or better plagron light mix? I use then only soil? or mix with perlite or something else?

Those should be good as they are. Many growers use them and follow the fertilizing instructions. And if something does happen you can contact the other growers here or contact the company for help.

What you had been thinking of before would have been an unknown soil because no one would be exactly sure of what was there. You might have read messages where some call unknown mixes "frankensoils" because they are like Frankenstein's monster.

 

[josep90]

Those should be good as they are. Many growers use them and follow the fertilizing instructions. And if something does happen you can contact the other growers here or contact the company for help.

What you had been thinking of before would have been an unknown soil because no one would be exactly sure of what was there. You might have read messages where some call unknown mixes "frankensoils" because they are like Frankenstein's monster.

Really dont know, i growed 7 times for now and all time use this mix. Coco brick is easy for transport

What do u thing about reuse soil? and add 50% new soil all new grow?

 

[SmokingWings]

What do u thing about reuse soil? and add 50% new soil all new grow?

It is what a lot of us do instead of throwing away the old for no reason. Some reuse for a couple of grows and some add in new after each grow.

 

[josep90]

It is what a lot of us do instead of throwing away the old for no reason. Some reuse for a couple of grows and some add in new after each grow.

If I add 50% of the new soil to each grow, I suppose it should be fine?

 

[SmokingWings]

If I add 50% of the new soil to each grow, I suppose it should be fine?

Sure will.

 

[BAKIND]

I grow in hydro, and I get yellowing leaves in every grow at some point during flower. It's inevitable. That looks normal.