Leaves yellowing in week 6 of flower

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Sunnysmoke

New Member
Hello all,

Joined up so I could ask for some advice.

I am growing two white widows and one Jack Herer. All three plants are in week 6 of flower and over the last few days I have been seeing yellowing of some of the fan leaves. There are only a few on each plant, but they're all on the larger fan leaves around the middle of the plant. I have narrowed it down to either magnesium or potassium deficiency following a search.

Please see attached picture and any help would be appreciated. The pictured plant has been light green from the start, but the other two look perfect. It's odd that the yellowing of the leaves has happened at the same time on all three as I haven't changed anything recently.

Thank you,20190216_085836.jpg
 
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CannaCountry

Well-Known Member
I would venture to say if you're 6 weeks into flower, you're rounding the corner to maturity. As your plant matures it will slowly begin to 'fade' (large fan leaves yellow up and die). This is a good thing. And while some here may say you need 'more nitrogen'; at this stage of the game I would tread lightly if you feel it necessary to give it. Overall your plant looks decent; good luck.
 
3rd Monkey

3rd Monkey

Well-Known Member
Like canna country said, if anybody tells you to add N, you tell them to go straight to hell lol.

She is hungry though. Phosphorus and potassium.
 
S

Sunnysmoke

New Member
Thanks for your replies, both. I'll give them a heavy dose of bloom nutes on the next watering.

Here are all 3 of them. The Jack Herer is the front left and the other widow is back left. Vegged for 6 weeks so they're huge!

20190215_073942.jpg
 
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Blitz35

Well-Known Member
Looks like you're in mid-flower..at least a month left for the one in the first pic. It may be a bit early for that one to be yellowing naturally..it appears to be magnesium related. She looks nice, leaves have a nice luster to them and seems to be healthy. I'd say maybe try a bit of epsom salt for that one..half to 1 teaspoon for the gallon of water, nothing drastic, you seem to have done well in growing them!
 
S

Sunnysmoke

New Member
Thanks guys!

Quick question. If they don't require more nitrogen, is it ok to give bloom nutes (NPK 5-5-10) or should I just use PK boost (PK 13-14)? I've also got some calmag, so is it worth using that?

Thanks :)
 
polishpollack

polishpollack

Well-Known Member
I would use a well-rounded bloom fert, one that has nitrogen. A flowering plant needs nitrogen in flower, but in smaller amounts. Then make sure you stop feeding at least one week before harvest and a flush then might be a good idea. Then let it die or harvest at will.
 
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Blitz35

Well-Known Member
Sunnysmoke said:
Thanks guys!

Quick question. If they don't require more nitrogen, is it ok to give bloom nutes (NPK 5-5-10) or should I just use PK boost (PK 13-14)? I've also got some calmag, so is it worth using that?

Thanks :)
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You still need nitrogen, they are not that close to being ready. Usually, on a healthy plant, you can cut out the nitrogen the last 10-14 days (3-4 waterings). By the time you reach mid-flower, the doses of nitrogen can be reduced..again, assuming the plant is in good health. Your 5-5-10 is good, and maybe a bit of the pk 13/14 for the 2-3 weeks of mid-flower. Hopefully you also have the micros included somewhere. Cal-mag i never used as i use tap water, with RO it's a must. Usually in mid-flower..the need for calcium isn't as big as in veg, and the plant uses more magnesium at that point, so epsom salt may be a better alternative than cal-mag as sulfur is also in higher demand at that point..plus some cal-mag contains nitrogen as well, which you usually don't need 'extra' of at this point.
 
S

Sunnysmoke

New Member
Blitz35 said:
You still need nitrogen, they are not that close to being ready. Usually, on a healthy plant, you can cut out the nitrogen the last 10-14 days (3-4 waterings). By the time you reach mid-flower, the doses of nitrogen can be reduced..again, assuming the plant is in good health. Your 5-5-10 is good, and maybe a bit of the pk 13/14 for the 2-3 weeks of mid-flower. Hopefully you also have the micros included somewhere. Cal-mag i never used as i use tap water, with RO it's a must. Usually in mid-flower..the need for calcium isn't as big as in veg, and the plant uses more magnesium at that point, so epsom salt may be a better alternative than cal-mag as sulfur is also in higher demand at that point..plus some cal-mag contains nitrogen as well, which you usually don't need 'extra' of at this point.
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I've been using Tesco bottled water for the whole grow, which is Ph 6.2. I've checked the run off after watering and (although it's not the most accurate method) the litmus paper test is exactly the same colour as the water in the bottle :)

I'll get some Epsom salt and use that for tonight's watering, as the yellowing on the plant in the original picture is getting more severe, to the point that one fan leaf finger almost looks white. Hopefully I'll catch it before it becomes an issue!

Thanks
 
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Blitz35

Well-Known Member
Sunnysmoke said:
I've been using Tesco bottled water for the whole grow, which is Ph 6.2. I've checked the run off after watering and (although it's not the most accurate method) the litmus paper test is exactly the same colour as the water in the bottle :)

I'll get some Epsom salt and use that for tonight's watering, as the yellowing on the plant in the original picture is getting more severe, to the point that one fan leaf finger almost looks white. Hopefully I'll catch it before it becomes an issue!

Thanks
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Do you have an updated pic of that plant?
 
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Sunnysmoke

New Member
The yellowing has got worse after watering with nutrients. I gave Epsom salt to the largest widow last night and foliar fed them all with bloom nutrients, some PK boost and Epsom salt 30 minutes before lights on last night. The runoff PH is still perfect so it can't be a lock out.

I'll get some pictures later, but it's odd as the yellowing seems to occur on certain areas of the plant (like all down one side) but I've been turning the plants so it can't be environmental factors. Odd!

Any help would be appreciated :)
 
Renfro

Renfro

Well-Known Member
Thats something deficient as it's happening in the middle of the plant I wager calcium deficiency..
 
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CannaCountry

Well-Known Member
Out of curiosity, what medium are you using? How often do you feed / water? At what strength and at what schedule? You mentioned you were at week 6 of flower...how much longer do you think you have to harvest?
 
polishpollack

polishpollack

Well-Known Member
That's not nitrogen def. Something else is wrong. You don't need the PK boost. I wonder if you've over done it on the ferts. If that's not it, then a different nutrient might be missing.
 
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Sunnysmoke

New Member
Thanks chaps,

I'm growing in Biobizz all mix, watering about every 3 days. I use two litres of water for each watering, and the pots are 12 litre capacity. I've been feeding them twice then using plain water then back to feeding again.

I started by giving half of the recommended nutes and now I'm giving at full strength.

I have used calmag 3 times for each plant and Epsom salt only once last night (foliar feeding all 3 and in the water for the largest widow).

From the last plants I grew (my first ever grow, which were white widow autos) I have checked the pictures and it seems like the Jack Herer is 3-4 weeks from harvest and the widows are 4-5 weeks away.

Thanks again for the help. The Jack is due a watering tonight, so I'll use plain water and see how the yellowing looks.
 
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S

Sunnysmoke

New Member
Hmm, maybe it is nutrient burn. Would a flush of the pots hurt them at this late stage, as I'll want to flush for at least a week before harvest?
 
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Blitz35

Well-Known Member
I would highly doubt that this is calcium related as someone mentioned...nothing in the pics suggest that! It doesn't appear to be nutrient burn either. When i first looked, i thought it may be a heat issue in that corner, but you say you rotate them, so maybe not. One thing i don't understand, why would you be foliar feeding in mid-flower? Not to mention, you can't just put any type of fertilizer with water and expect foliar feeding to work. I would cut out foliar feeding at this point! What are your temps/humidity? You're giving water in the pot every 3 days, and spraying the leaves? Not very common, especially in mid-flower! If plants get their water from foliar spray, they have less need to take water from the pot, which can lead to deficiencies/over-watering.
 
S

Sunnysmoke

New Member
Blitz35 said:
I would highly doubt that this is calcium related as someone mentioned...nothing in the pics suggest that! It doesn't appear to be nutrient burn either. When i first looked, i thought it may be a heat issue in that corner, but you say you rotate them, so maybe not. One thing i don't understand, why would you be foliar feeding in mid-flower? Not to mention, you can't just put any type of fertilizer with water and expect foliar feeding to work. I would cut out foliar feeding at this point! What are your temps/humidity? You're giving water in the pot every 3 days, and spraying the leaves? Not very common, especially in mid-flower! If plants get their water from foliar spray, they have less need to take water from the pot, which can lead to deficiencies/over-watering.
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I started foliar feeding when the yellowing appeared as I panicked and thought it was a nutrient deficiency.

My temps are around 25 degrees Celsius and humidity is between 35 and 42 percent.

I moved the light up as far as it would go last night in case it is light burn, but I don't see how it could be as the leaves closest to the light were fine, and it's affecting the shortest plant the most.

:)
 
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