HELP! Small buds on healthy big plants.

[sarek]

So I am an experienced grower and have a new problem. I have good genetics and good everything but small narrow, long buds. Quality is good but yield is terrible.

Rockwool 6" Hugos vegged big
1000W good lights
Air cooled hoods
cool temps
Lots of air and fans
No pests at all
No fungus or PM
drain to waste
GH 3 part around 900 ppm, ph 5.8ish (123 formula on label)
Switched to GH 2 part Lucas Formula 3 weeks ago ppm 1000 (0.5 scale)
No other additives

The plants are large and mostly healthy, 4 under one light, different well known strains. Not many leaves yellowing so its not the disease/pests/unhealthy thing. Big 2 inch diameter stalks. Really healthy. Part of the problem might be plants are too big, but even when the buds on top right under light are still very small and wispy. Sometimes the buds are big in overall size like a Cola, but instead of forming a monster cola they form 5 little useless budlets.

One unique thing, I use dosers so I cannot vary the nutrient easily. I know many of you may say thats the problem, but a friend is running 96% the same system with very different results. So I run the same nutrient profile the whole 9 weeks. I am new to drain to waste. I have used recirculating for years and would often use Flora Nova, same PPM all thru flowering with GREAT results, no additives. But now, drain to waste is sort of new to me.

So this is not a basic beginner problem (tho its probably something easy). I am wondering if anybody recognizes this kind of problem.

I have cleaned hoods and lights recently. I have Raptors, Radiant and MEllonhead. Do people have good luck under Raptors? Hood is much bigger, tho it may also be weaker light.

My guess is too much Nitrogen so a few weeks ago I switched to Lucas formula. Too much nitrogen might cause this problem I think.

I have plastic 4x4 tray underneath. Normally I build a little tilt into them, but this time I did not and I was running a little experiment where I let 1 inch of water sit in gullies. Many roots would grow into gully and grow vigorously. I had an idea that this could be from the roots getting too many nutrients, tho some plants dont send roots down into tray which may screw that hypothesis up.

So maybe switching to Lucas will make a difference tho I think that the 3 part that I had been using should work better.

I am going to try to keep troubleshooting this as much as possible, my hope is somebody will say "Oh, I had that problem once, it was X"

The basic question is what causes small buds on really healthy plants?

_______________________________________________________________________________________

Editing the thread down a bit. Much consensus seems to be related to Temp or VPD (Vapor Pressure Deficit). VPD is the product of Temp/Rel Humidity.

Temps seem to be that night temps below 60 are bad. Medium as well. Here are a few links

http://www.weedfarmer.com/cannabis/haze_guide.php

Temp differential day/night affects stem elongation
http://www.cannabisculture.com/articles/1536.html

Ed Rosenthal
http://www.quicktrading.com/tips16.html

Pot Potency (good overview)
http://www.cannabisculture.com/articles/2159.html

 

[SeaMaiden]

How familiar are you with VPD? Those are the only parameters I don't see mentioned here that could have an effect. It would be helpful to see the plants, to at least be able to gauge leaf turgor, angle, a bunch of other things that may indicate the plants' happiness, or lack thereof, with the vapor pressure deficit.

I quick primer and calculator: http://www.hydro.co.nz/1_information/1_vpd/info_vpd.html

Oh yeah... when you say 'cool temps', what do you mean, exactly? I've done a *lot* of cold growing and it leads to exactly what you're describing.

 

[Scrappy-doo]

Need pics bro. What genetics and how far into flower are they?

 

[sarek]

I got a few pics, I just gotta excise the exif info. It was so easy on PCs but MACS ironically are harder for me to do graphics with. (Maybe they are more secure tho)

I am running OG, Grape Romulan, J1. Well known strains that I know very well that are behaving differently. I do perpetual harvest so this is different ages so its a systemic issue that affects everything.

SeaMaiden, thats some good points. I have not really heard of VPD tho I often implicitly acknowledged it. This is a cool place in No. California. I will verify but I think it gets to 60F at night and 75 in day which from a temp standpoint is fine I think. In general, cool temps (but not 40,s or 50's) are good.

The humidity component thos could be a problem. I have not paid much attention to that but it is on the humid side there. I just did some quick calculations, my night temps r around 15C, and day maybe 23C which is 50 RH night and 70RH during day. I THINK during the day the humidity has been around 60-70RH maybe. I have no idea what night RH Is.

In general, I think RH goes down at night, perhaps since the temps cool it has less moisture holding ability. But perhaps my night humidity stays too high.

But a little reality check too, I have no bud rot issues nor too many other problems like mold. Of course, such wispy buds would not probably get moldy!

I will try to start measuring this alot more. I think this problem has gotten worse as winter has arrived with it being brutal the last two months. This is a promising lead. I think its great to understand this concept anyways, since I think its an 800 pound gorilla in the room. Very, very few growers pay much attention I think to this combo other than to lower temps. In fact I have worked hard to have low temps, but perhaps I have been too sucsessful!

Here is a question back at ya. What about day vs night VPD? What is the importance of each? Maybe its the night temps that are the problem when I am not there?

Maybe a dehumidifier would be a good investment.

A couple links
http://www.icmag.com/ic/showthread.php?t=153547 Good detail on VCD
and this next one touches on types of photosynthesis
http://www.mrnice.nl/forum/4-talk-shantibaba-mrnice/3459-humidity-vapour-pressure-deficit-vpd.html

 

[RubeGoldberg]

Drop the ph down to like 5.5-5.6

at 5.8 its just high enough where the plants can't access some of the important micronutrients, once your 5.8 nutes enter your roots, the water pH will just climb from there (check your runoff, you'll see)

so your plants are missing out a bit, I'd also stick with the 3 part formula rather than lucas

 

[sarek]

Picture

Picture

Here is a picture of I think a 9 week bud. I changed the colors a bit cos of white balance, the pic was all yellow. Notice plant is healthy and vigorous but budlets are dinky. It should be ready to harvest here. This is what buds look like at 4 weeks! Furthermore, this was right under light, not way down on plant. Usually buds near light finish earlier and faster.

 

[Hydro-Soil]

My guess is too much Nitrogen so a few weeks ago I switched to Lucas formula. Too much nitrogen might cause this problem I think.

I would tend to agree. See? Something simple.

Stick with Lucas for the full run, keep your pH at 5.8 so you get the full range of absorption in the root zone.

Stay Safe!

 

[SeaMaiden]

Sarek, I know my girls would like the temp/RH numbers you're providing. I have found they really perform best when RH is >50%.

The plant you've pictured looks like it's still popping a lot of new pistils, wants to go long. Otherwise, nice and compact, healthy looking growth (I do see reddened petioles, not uncommon for me to generate with my indoor grows). Maybe she just wants to go long, ya know?

 

[sarek]

With new Lucas formula its 5.4-5.5, I was even thinking of bringing it up a bit. I may adjust ppms down from 1000 ((2000mS) to 850-900 on my new Lucas. Its sort of trippy, I think I am close on so many measures, but there must be one that is off. Will start measuring humidity more today. Also tweek nutrients. What is good ppm (0.5 scale) for Lucas in drain to waste)?

Can one use Lucas at same ratio the whole time? Thats a challenge for me is I cannot vary ppms easily for different, so I just use one ppm rate for everything. But I did that alot w recirculating to no problem.

 

[Grass Lands]

to me they look a little to healthy for 9 weeks, unless they are a sativa dom plant that needs 12+ weeks to run its course...also looks like a little to much leaf curl which could indicate to much N.

 

[Hydro-Soil]

With new Lucas formula its 5.4-5.5, I was even thinking of bringing it up a bit. I may adjust ppms down from 1000 ((2000mS) to 850-900 on my new Lucas. Its sort of trippy, I think I am close on so many measures, but there must be one that is off. Will start measuring humidity more today. Also tweek nutrients. What is good ppm (0.5 scale) for Lucas in drain to waste)?

Can one use Lucas at same ratio the whole time? Thats a challenge for me is I cannot vary ppms easily for different, so I just use one ppm rate for everything. But I did that alot w recirculating to no problem.

I'd up that pH, yes. Otherwise you're going to start seeing "low-pH" leaf curling on your new growth... difficult to see since it's all bud now. Won't be able to tell until it's too late.

Yes, with GH nutes anyway the ratio stays the same 1/2, 1 part micro to 2 parts bloom. In coco it's 6/9(edit: What ratio is that? heheh), generally 6 micro and 9 bloom.
@ .05... I usually kept the ppm around 800-900 unless I ran into a nute hungry strain.

Hopefully you've just stalled the development time by a couple weeks and they'll finish late but fine.

Could there be other light factors? Perhaps a light coming on early or turning off late? that would definitely slow down the development.... not hurt anything but definitely slow things down.

Stay Safe!

 

[Scrappy-doo]

Those budz have a LONG way to go. They're not even close to finished growing.

I can't tell much from that photo as far as the plants health. If you are able to take some better pics perhaps with the light off that would help. I Can't even see the buds that well, but what I can see is really immature still. Looks like the leaves could potentially be showing signs of heat stress too. How close to the lights are they?

 

[growinthehills]

What are your temps? lights on and off?
I have seen this same problem when temps are too low... The plants stay healthy and look nice but the buds just don't develop correctly. Resulting in allrite bud but low yields and larfy nugs.

 

[spearzy]

id say temps too low at night are seriously slowing down flowering.

spearzy

 

[spearzy]

also the leaf tips are all curling downwards at the ends isnt that usually a sighn of too much feed/nitrogen?

 

[sarek]

I measured temps a bit more carefully. I think it might be low temps. VPD seems within range but maybe temps too cool. It is middle of winter and I have not spent a winter here yet.

low hi = 50 / 65-70. I had always thought that cool temps were good, the cooler the better, but maybe that peters out around 55/75 or 60/75 Thats to say that if you keep that 10-15 difference between night and day, and optimal day is 75, then 15 below that is 60 (60/75). I have done alot of this and its been great. Maybe it gets 5 below that in my past and its been mostly good. More trichomes than hot temps.

One thing is that day temps often fluctuate but its often more similarity at night.

Take it down another 5 to But here I am finding too cool. So maybe the way to think is that 50/65 too cold.

I think 60 is a cold night in many places cannabis grows best.

Maybe the buds are a bit bigger with temps on warmer side. But maybe you lose a bit of yield (maybe), but make it up for it with more trichomes and less fungal issues in cooler temps.

What is everybodies experience with temps?

75/90 5
70/85 4
65/80 3rd if towards cooler
60/75 1st Best Optimal
55/70 2nd best if sometimes warmerish
50/65 6 growth really slows down.

I am talking generalities. There are many other permutatins and you could throw in humidity as well. Orchids for example can handle cold temps much better if kept dryer. Water + cold messes up orchids.

Too Cold?

http://www.icmag.com/ic/showthread.php?t=230421&highlight=cold

 

[GanjaPharma]

just a guess , but are you running old bulbs?

 

[SeaMaiden]

Aaahh... well, sarek, if daytime temps are barely breaking 70F, then I would have to agree, though the suggestion regarding age of bulbs is certainly worthy of good consideration. I've done a lot of cold growing and I've found that higher RH values coupled with temps well into the 70s are the ticket. I've found it's far better to let it get a little too warm (>80F) than too cold (<68F), or everything slows down and you get larfy buds.

 

[Hydro-Soil]

Aye... 75-78F during the day and 10 to 15 degrees cooler at night, usually 10 with me.

Definitely change your lamps if you've been running them a couple grows, especially the cheaper ones.

Stay Safe!

 

[sarek]

Funny, for years I have been chasing cold temps, cos often too hot. Never really had a problem with too cold! Colder buds were more frosty, maybe a bit smaller but looked better. We have had an ongoing problem with some kind of fungus in hugos. Caught it 4 years ago and its been a pain. Not sure what, maybe Phythium or something. Its now endemic in our plants. Warm temps make it worse so thats another reson we like coool.

But I guess this new room stepped beyond cool into COLD. So I will take lots of measurements and buy a fan/heater like a Vornado I think. That should kick up the temps day and night.

The bulbs are mostly 7-8 months old. I normally change them at 1 year, even then, its a slow gradual decline as a few times I have accidently forgotten about bulbs and lets a few run for 1 1/2 - 2 years and still have much better results than this problem. Also, a few have been replaced recently.


Will take some more measurements and let cha know. This temp thing really can affect yield I see. I have to start paying alot of attention to this. I wonder what the subtle differences are pertaining to subtle difs. Like is night temp as important? optimal temp difference day/night? Often it gets colder/warmer for 5 days at a time. Do the dips make a dif?