Possible N deficiency?? Autopots help

[Marcorfl]

Hey i have a autopot grow underway, everything has gone perfectly smooth up until probably 1-2 weeks ago (just after 12/12 flip) where I’ve noticed the plants have taken a slightly lime green look and a lot of the lower leaves are yellowing out and dying. Anyone help with ideas as to whats up. Seems to definitely be spreading from bottom to middle now. I do have a little diary on the go but I didn’t get any responses so came here. Thanks in advance

 

[OldMedUser]

Hey i have a autopot grow underway, everything has gone perfectly smooth up until probably 1-2 weeks ago (just after 12/12 flip) where I’ve noticed the plants have taken a slightly lime green look and a lot of the lower leaves are yellowing out and dying. Anyone help with ideas as to whats up. Seems to definitely be spreading from bottom to middle now. I do have a little diary on the go but I didn’t get any responses so came here. Thanks in advance

The stretch period is a huge growth spurt for the plants so they might not be able to pull nutrients in from the soil fast enough and are robbing some of the mobile nutes like N from the older leaves. That high demand will drop after the stretch and go back to feeding levels like they were before the flip. I'd give them a bit more of everything right now leaning toward the bloom side of the equation. Extra light and some CO2 during the stretch really rocks them.

After the stretch I feed at pre-flower levels tapering off while increasing K over P and lowering N to near zero the last 3 weeks or so. I want to see those old fan leaves going soft and yellow as the end nears so I know my plants aren't loaded up with extra nutrient salts when I chop. I don't flush at all but they get bugger all to eat the last couple of weeks other than some Epsom Salts and a little K.

Those lower leaves don't get enough light to be of much use to the plant other than reservoirs for spare nutes the tops can steal as needed so as long as still a bit green and healthy I leave them.

 

[coreywebster]

What medium and what EC are you feeding?

 

[Marcorfl]

The stretch period is a huge growth spurt for the plants so they might not be able to pull nutrients in from the soil fast enough and are robbing some of the mobile nutes like N from the older leaves. That high demand will drop after the stretch and go back to feeding levels like they were before the flip. I'd give them a bit more of everything right now leaning toward the bloom side of the equation. Extra light and some CO2 during the stretch really rocks them.

After the stretch I feed at pre-flower levels tapering off while increasing K over P and lowering N to near zero the last 3 weeks or so. I want to see those old fan leaves going soft and yellow as the end nears so I know my plants aren't loaded up with extra nutrient salts when I chop. I don't flush at all but they get bugger all to eat the last couple of weeks other than some Epsom Salts and a little K.

Those lower leaves don't get enough light to be of much use to the plant other than reservoirs for spare nutes the tops can steal as needed so as long as still a bit green and healthy I leave them.

Wow thanks bro. Really appreciate the in depth response. I have upped the feed from the last water change. Didn’t think about them nit being able to pull it fast enough from the coco! That’s interesting. Hopefully they perk up now the stretch is slowing considerably. They are currently getting 480w from the lumatek 600w pro which gives about 700/800ppfds at canopy.

 

[Marcorfl]

What medium and what EC are you feeding?

Currently in coco (DNA coco with cork) with 1.5” lava rocks at the bottom. After having issues on my last grow i was convinced by a hydro shop owner to push my ec up a lot more. On 12/12 flip yhey we’re probably getting about 1.5 ec (a&b and calmag) but after changing res this weekend i have increased it to 1.9. PH 5.9-6.2

 

[OldMedUser]

Wow thanks bro. Really appreciate the in depth response. I have upped the feed from the last water change. Didn’t think about them nit being able to pull it fast enough from the coco! That’s interesting. Hopefully they perk up now the stretch is slowing considerably. They are currently getting 480w from the lumatek 600w pro which gives about 700/800ppfds at canopy.

They don't look like they are suffering at all and it's pretty normal for any plant to lose older leaves. If lots are all doing it then something needs doing to correct it but a leaf here or there is no biggy.

Speaking of feeding plants I was just taking a break from top-dressing my plants in preparation to flip to 12/12 in about a week. I'm using peat based ProMix HP with a lot of organics mixed in and they seem to like it. Did mostly DWC for the last 20 years and swinging over to the greener side and surviving.

Back to the plants so good luck!

 

[Marcorfl]

Here are some updated pictures.

 

[coreywebster]

Currently in coco (DNA coco with cork) with 1.5” lava rocks at the bottom. After having issues on my last grow i was convinced by a hydro shop owner to push my ec up a lot more. On 12/12 flip yhey we’re probably getting about 1.5 ec (a&b and calmag) but after changing res this weekend i have increased it to 1.9. PH 5.9-6.2

Hmm.. can't see your EC or PH been an underfeeding issue.
I don't go anywhere near that high.

Sometimes leaves that do t get enough light are deemed useless for photosynthesis by the plant and repurposed as food and will yellow and drop off.

But there's something going on here.

I might consider lifting them out the tray and top feeding for a few days.
I'd also consider running some ph water through and taking an EC reading of your run off first.
This way you can check for salt build up causing a lock out.

I'm assuming your coco brand comes pre washed , which most pre bagged stuff does.

My thoughts are with autopots you get a wet bottom and a top that dries out, this could create salt build up if running high EC through VEG which won't necessarily be seen till flowering when everything falls to pieces.

I might be wrong, but it's an easy task to try so you can eliminate that as a possibility.

 

[Marcorfl]

Ok well i popped into my local hydro store and the guy said definitely underfed (Nitro def) possibly due to higher demand during stretch. Plants seem to have slowed up on the drinking but water level is dropping slowly so hopefully the raised food will sort my issues out

 

[Marcorfl]

I also did a light spray with optic foliar avoiding bud sites as best as possible

 

[Marcorfl]

@coreywebster hi mate, sorry to tag you but after 5 days it doesn’t seem to be spreading fast if at all. The already affected leaves are only getting worse which is ok for me. I haven’t done anything over the past 5 days to them, is it possible that now (day 29) they will not get any worse as they need little N now? I was about to run oh water through but thought I’d hop on here and ask first lol.

 

[Marcorfl]

Considering its not getting worse fast I didn’t want to go doing anything that could cause them to get worse lol. Any and all advice appreciated

 

[coreywebster]

@coreywebster hi mate, sorry to tag you but after 5 days it doesn’t seem to be spreading fast if at all. The already affected leaves are only getting worse which is ok for me. I haven’t done anything over the past 5 days to them, is it possible that now (day 29) they will not get any worse as they need little N now? I was about to run oh water through but thought I’d hop on here and ask first lol.

Yeah cool, if its not getting worse leave it and see how they go.

 

[Marcorfl]

Yeah cool, if its not getting worse leave it and see how they go.

Thanks mate. Any signs of getting worse I’ll do as you suggested and run phd water and test ph and run off. Photi taken today

 

[buckaclark]

Thanks mate. Any signs of getting worse I’ll do as you suggested and run phd water and test ph and run off. Photi taken today

Don't eliminate N just yet .IMO

 

[Marcorfl]

Here’s what they are looking like at day 29. Seem happy enough now, can’t wait to see how bug they get in the next 4-5 weeks

 

[Marcorfl]

Day 36 of flower.

 

[Marcorfl]

Day 41. Seems as tho they are definitely starting to swell now! Hate waiting but love watching. Comments welcome

 

[Marcorfl]

Close ups

 

[Marcorfl]

Some real nice colours coming now. Week 8 day 1