Plants at day 91 of flower, not looking healthy

[d42zero]

So some of you may know that I've had a CRAZY long flower, currently at 91 days. Everything was looking good until maybe a month to 1.5 months ago, when the plants started to slow down and nothing really seemed to be happening. Trichomes basically haven't changed in a month. I was at my local hydro shop recently and I asked them about the plants seemingly having trouble finishing, I showed the guy some photos and he thought they looked very stressed.. he gave me some really good ideas but I like to get a few opinions and see what matches up so here we are.

My journal is full of photos if you want to go back, as well as daily min/max temp and humidity. But to keep this post simple minimum temps have been are around the 20degC area (65-70F) and maxes around 28deg C (80-85F), with humidity fairly steadily between 45 and 55%. Nutes are around 600ppm and 6.5pH.

Current photo of the plant that looks the most healthy:

You can see some browning of the tips, and some leaves are curled up a bit. This one doesn't look too bad to me.

Here's a current photo of the least healthy looking plant:

This does not look good to me. I ignored the yellowing leaves for a while as I thought that was part of flower, but sugar leaves are dying too and there's a big chunk of dead bud in there.

The hydro shop guys were super helpful but they gave me multiple things to change... I'm working on those but I would like to narrow down what's going on so that I can avoid it again in the future. Their list of stuff to work on was:

1. Vent exhaust outside the room - I was venting the tent into the room as it was easier to control temp/humidity that way (especially through winter) and I would open the room a few times a day to exchange the air. I've since vented the tent outside the room but the tent has vented into the room since the very start and things were going fine until about a month ago, so it seems more likely that something changed a month or so ago..
2. Change daylight hours from 8pm-8am, to 8am to 8pm.. my min/max temps are only a few degrees apart, and the guy said I should be chasing a 10degC differential between min and max... switching the plant's daytime to match our daytime would help this. This one does make a lot of sense as the weather changed about a month ago, through winter I was getting differentials of more like 8-10degC.
3. Reduce daylight hours from 12 to 10 - I will do this today along with point 2.
4. Reduce nute strength (currently ~600ppm) as the browned tips may be a sign of nute burn, although the leaves have had little brown tips for almost the whole grow. I can do this from today.
5. Reduce frequency of watering from 3x daily (1L per plant per water) to 2x daily.
6. Remove my runoff reservoirs to get the plants further away from the lights - they were very close. I've done this and they're now about 12 inches from the lights.

It's worth noting that the healthy looking plant is drinking much more water than the unhealthy looking one. When I removed the runoff reservoirs the healthy one had about half the runoff of the unhealthy one, despite being watered exactly the same amount.. and now that they're sitting in trays instead of reserrvoirs, I can see that there is almost no runoff from the healthy one but there's quite a bit from the unhealthy one.

What do you guys think?

 

[Old Salt]

Flush them with at least the pot size of water at pH 6.0. This should clear any nutrient or salt buildup in the root zone. Start feeding them again with the lower concentration. I can't give an exact number as you didn't mention the nutrients used.

This is what led me to believe that you have a lockout situation.

It's worth noting that the healthy looking plant is drinking much more water than the unhealthy looking one.

Make absolutely certain that you are feeding until you get a minimum of 10% runoff every time from each plant. My plants get fed 5 - 10% of the pot volume three times per day, getting this amount of runoff (11l pot .5 - 1l nutrient solution). This provides a continuous flushing action for the coco/perlite, and will prevent this from happening again.

I did have my plants stall for this reason in an earlier grow. It took several days for them to recover.

 

[d42zero]

Flush them with at least the pot size of water at pH 6.0. This should clear any nutrient or salt buildup in the root zone. Start feeding them again with the lower concentration. I can't give an exact number as you didn't mention the nutrients used.

This is what led me to believe that you have a lockout situation.

Make absolutely certain that you are feeding until you get a minimum of 10% runoff every time from each plant. My plants get fed 5 - 10% of the pot volume three times per day, getting this amount of runoff (11l pot .5 - 1l nutrient solution). This provides a continuous flushing action for the coco/perlite, and will prevent this from happening again.

I did have my plants stall for this reason in an earlier grow. It took several days for them to recover.

Thanks for the info, sorry I should've included that I flush the plants fortnightly with 60l plain pH6.5 water (3x pot size). They get watered with 1 litre each 3x daily, so in 20l pots that's about 5% pot size each watering.. Maybe I'll up that a bit.

Is the logic behind flushing with 6.0 that the pH will creep up between flushes, so flushing with 6.0 means if the pH does creep up it might creep up to around 6.5?

 

[Old Salt]

Thanks for the info, sorry I should've included that I flush the plants fortnightly with 60l plain pH6.5 water (3x pot size). They get watered with 1 litre each 3x daily, so in 20l pots that's about 5% pot size each watering.. Maybe I'll up that a bit.

Is the logic behind flushing with 6.0 that the pH will creep up between flushes, so flushing with 6.0 means if the pH does creep up it might creep up to around 6.5?

No, 6.0 is the center of the recommended range for hydroponics. Coco/perlite is classed as a drain-to-waste hydroponic system. Flushing with water is rarely done. A nutrient solution should always be used. Regardless of the volume used, a minimum of 10% run off is required every time the nutrient solution is applied. This treatment is an exception as your plant is in distress.

 

[d42zero]

No, 6.0 is the center of the recommended range for hydroponics. Coco/perlite is classed as a drain-to-waste hydroponic system. Flushing with water is rarely done. A nutrient solution should always be used. Regardless of the volume used, a minimum of 10% run off is required every time the nutrient solution is applied. This treatment is an exception as your plant is in distress.

Gotcha, that makes sense.

Is it possible this is just a pH thing then? I was running pH 5.8 thru veg and I thought I read that I was supposed to up it to 6.5 thru flower. The leaf yellowing looks very similar to when I wasn't watering enough and the pH in the media was creeping right up.

Would it be worth dropping my nute pH back to 6.0 to see if that helps?

 

[Old Salt]

Gotcha, that makes sense.

Is it possible this is just a pH thing then? I was running pH 5.8 thru veg and I thought I read that I was supposed to up it to 6.5 thru flower. The leaf yellowing looks very similar to when I wasn't watering enough and the pH in the media was creeping right up.

Would it be worth dropping my nute pH back to 6.0 to see if that helps?

It may. I run at 5.8 until the flip. 6.0 during the stretch, and then 6.2 to harvest. There are gaps in the bioavailability of nutrients when hydroponics is used to grow. This covers the gaps. Some change the pH with every new batch of nutrient solution, varying it between 5.5 and 6.5. I usually recommend staying within 5.7 and 6.3 as I have no way of knowing what's being used to measure pH. The readings on many of the low cost devices are ±0.2 pH of the actual value when they are properly calibrated.

 

[d42zero]

It may. I run at 5.8 until the flip. 6.0 during the stretch, and then 6.2 to harvest. There are gaps in the bioavailability of nutrients when hydroponics is used to grow. This covers the gaps. Some change the pH with every new batch of nutrient solution, varying it between 5.5 and 6.5. I usually recommend staying within 5.7 and 6.3 as I have no way of knowing what's being used to measure pH. The readings on many of the low cost devices are ±0.2 pH of the actual value when they are properly calibrated.

Hmmm that's interesting. I have a HM PH-80, it's calibratable but now I think about it I haven't done that for ages.. I'll do it tonight. I might drop my pH down a few points and see if that helps, it didn't occur to me earlier that these symptoms are quite similar to when I was getting pH creep earlier in my grow..

 

[Old Salt]

I have an HM Digital pH-200. I mix nutrient solutions twice a week at the most. Everytime i mix a batch, I check the calibration of the pH-200 with GrowTek's pH Buffer #7. I do a full 3 point calibration monthly. It adds $14 CAD to every grow, but iI feel it's well worth the cost.

 

[HugePeckerhead]

I have an HM Digital pH-200. I mix nutrient solutions twice a week at the most. Everytime i mix a batch, I check the calibration of the pH-200 with GrowTek's pH Buffer #7. I do a full 3 point calibration monthly. It adds $14 CAD to every grow, but iI feel it's well worth the cost.

So I have a couple successful grows in....and never once have I ever checked the PH of anything. Each grow I use FFOF with their trio of nutes. Is it because I never go over the recommended feeding chart they have for the nutes? And only once have I had a plant showing a deficiency which were my white widow. ( was a cal mag issue and once I started a weekly feed I never seen the problem again)

 

[Old Salt]

It's the nutrients we use, and how we grow that determines the importance of pH testing. I grow in coco/perlite. Previously, I used the General Hydroponics' Flora Trio as my base. They needed it. I've switched to Mega Crop, and am currently adjusting pH as I did before. I may change later, but first I want a successful grow with the new nutrients.

 

[HugePeckerhead]

It's the nutrients we use, and how we grow that determines the importance of pH testing. I grow in coco/perlite. Previously, I used the General Hydroponics' Flora Trio as my base. They needed it. I've switched to Mega Crop, and am currently adjusting pH as I did before. I may change later, but first I want a successful grow with the new nutrients.

I wanted to explore different nutes but i also didn't want to change what's working for me. When I've gone through different journals and grows , I've noticed overwhelming attention to PH levels. ( Then you have me sitting here like why is this such a big thing with everyone because it's something I never needed to do. )

 

[Old Salt]

I wanted to explore different nutes but i also didn't want to change what's working for me. When I've gone through different journals and grows , I've noticed overwhelming attention to PH levels. ( Then you have me sitting here like why is this such a big thing with everyone because it's something I never needed to do. )

Same with me and TDS/EC. It's not needed the way I've been mixing my nutrient solutions.

 

[HigherTheHigh]

The brown patch half way up that cola isn't bud rot is it?

 

[d42zero]

The brown patch half way up that cola isn't bud rot is it?

I don't *think* so, that cola got right up next to the light and I think its a patch that died off from that... It's very very dry, not wet or moldy.

What do you think?

Should I just cut it out anyway? Doesn't look too appealing either way..

 

[d42zero]

The brown patch half way up that cola isn't bud rot is it?

Turns out it IS bud rot Pulled it apart and sure enough it was all mildewey and gross

I've removed the whole section from about 2" below that point.. there's a few areas I'm not feeling great about though, like the sugar leaves on this bud:

Some of the leaves look shitty (like the yellowed ones on the left) but others in the middle look kind of moldy... what do you guys think??

Humidity hovers around 45-60%, goes over 60 occasionally but not often... Is there anything I can do to stop this happening again?

 

[HugePeckerhead]

In flower I try to keep my humidity as low as possible 30-40% range. In veg my humidity is around 60%.

 

[d42zero]

In flower I try to keep my humidity as low as possible 30-40% range. In veg my humidity is around 60%.

How do you manage that? I have a dehumidifier running in the room (collecting about 2-3L per day), but I still can't get the humidity below 40% unless it's a crazy dry day and the outside air is down below that..

 

[HugePeckerhead]

I use an air conditioner along with the use of a dehumidifier.

 

[HugePeckerhead]

.....this is my first year growing inside heading into winter ( Pennsylvania winter ) so I'm sure I may need to change a few things soon as it's getting cold fast

 

[d42zero]

Hmm ok I'll look into that.. I have a portable air con, but I'm using its window-fitting to vent the air from the tent out the window, so I would have to vent the tent into the room and pump the A/C exhaust out the window..

I guess the A/C would still be moving air from the room the the outside, so that would exchange the room's air regularly...