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Questions on how to increase terpenes: light spectrum, cooler temps etc

greenops

Member
As a grower I crave for the amazing aromas, with that kinda taste that lingers in your mouth.

But more often than not, I end up with bland tasting nuggets. Virtually they really look fire, covered in trichomes and I'm more than happy with the yield, but the smoke is usually boring.

I'm following Simon's curing tutorial and nailed it a couple times, but it doesn't improve the taste and smell, if the smell has already disappeared before harvest time. So usually, the plants start to smell real nice early flowering, but lose it mid flowering.

I know that MH throughout flowering produces a lot of leaves and less denser buds, so I thought it maybe a good idea if I use my HPS for the first 5-6 weeks of flowering, so that the buds can fatten up a bit, then switch to MH for the last 2-3 weeks?

I did some reading and I found comparisons between the same cuts under HPS and MH. The MH or LED grown buds had a much more complete terpene profile.
It seems to me that the HPS somehow cooks or burns a certain group of terpenes at a given stage and temperature.
From my experience, it's around the 5th week where my flowering buds can lose their smell, while the leaves closer to the light turn pale and yellow. I've seen MH used in flowering and their leaves appear much greener.

However I read somewhere that MH bulbs shouldn't be used in air cooled fixtures, because it blocks the UV or something? Hope someone here knows if thats BS or true, because I'm very dependent on my air cooled hood.

Also, I've heard of dropping the night time temperature during the last 2 weeks or so and add ice cubes to the rez to "chill the roots" to improve terpene production. Is ther any truth to this? Seems easy to do but I don't wanna shock my plants with ice water if it does more harm than good. Plus dropping night time temperature may invite powdery mildew and other molds.

If any of you have other proven methods to improve terpense production and/or ways to reduce terpene loss please let me know.
 

Snype

Active member
Veteran
I use 1,000 watt HPS only and my buds has loads of flavor. You have to search for flavor in the pheno's that you grow. Some won't have that flavor and some will. Maybe you aren't searching or if you have cuts that are supposed to have flavor and don't, you must be doing something wrong. I don't like the top of the canopy to get over 75 degrees F because the buds just don't look as nice to me at those temps and I seem to get more resin and denser buds at cooler temps. It could be possible that you can lose some smells if the temps are too warm. I'd try to get your conditions in line and see if your flavor improves. Also keep the nutes on the low side as well to improve those flavors. I never go more than 2 EC.
 

greenops

Member
Thanks for your input Snype.

Genetics def has something to do with it. I get mine from Attitude Seedbank, usually I grow the strains that get a lot of positive feedback in the forums. I've harvested some 30 - 40 plants in the past 3 yrs since i started growing in a tent. And it's usually the same kind of genetics that retain the aroma til the end. But the piney, skunky type of smell gets weaker. That leads me to believe that certain terpenes get lost due to factors such as temps or light. I used to grow in soil and have a "less is more" mentality when it comes to feeding.

I guess your getting nice flavors with your HPS because you can keep your temps low. IN the past my temps regularly reached 80F. I made some improvements this run, so now hottest part of the tent is somewhere between 72 to 77F, avg 73 F tho. I got 400/600w hps in an aircooled hood, strong exhaust and 6 fans for circulation, all in a 1m x 1m grow tent.

However I'm already noticing how the leaves in the center of the scrog get lighter. Same thing I noticed in earlier grows. I can't raise my lights much more but I know it's far enough already. Does that ever happen to you?
That's why I think MH may help avoid that from happening, while improving terpene production.

Pics:

First bud is an Amnesia Lemon from Barney's. It's quite frosty, but smells and tastes very neutral, after smelling like some nice sweet citrus funk in early flowering. (Had 2 phenos, looked different, tasted same)

2nd bud is Fruity Chronic Juice. This fruity odor stayed til the end. But I have a feeling that if grown under diff lights it the taste could have been better.

3rd is my new set up. Feel free to tell me if u see something wrong.
 

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Granger2

Active member
Veteran
Terpines will evaporate. I use to have the same problem with low 80's and lights 18" above canopy. Beautiful potent buds, mild flavor. Raised lights, got temps to high 70's, and flavor improved dramatically. I use HPS and at 4 weeks into bloom, I supplement 4 hours/day with Reptile UVB lights. They make a noticeable difference. Good luck. -granger
 

Only Ornamental

Spiritually inspired agnostic mad scientist
Veteran
Hi Greenops
Concerning the air cooled hood: Is there a glass pane between the bulb and the plant or is it open on the lower side? Cause UV is blocked/reduced by most glass (except expensive silica glass) and many plastics, it is also not well reflected by many surfaces (best would be a reflective metal housing or an aluminium film).

I also observed with the Skunk #1 I had outdoors last year that they lost a lot of smell during mid- to late flowering. In veg, they were really reeking of old school superskunk (how I dislike that smell), then they nearly completely lost the aroma and only after uhhh... (*checking growth diary*) three months of curing did they develop something nice and remotely skunky but mainly sweet and fruity (not that bad after all but no Skunk smell like I know it :dance013: ). Also other strains changed heavily during mid- to late flowering.
Changes in terpene profil seem normal and haven't necessarily something to do with temperature or light. Well, those two also influence essential oil composition and production... what I want to say; maybe it's just the strains you chose.
Ask for example Sam, he should know it ;) .
 

idiit

Active member
Veteran
properly grown ( good organic soil very important) outdoor buds slow dried and then extensively cured give me the best terpenes. the best eye candy is usually indoors but the terpenes for me are best done as described above.

picture.php


^ this golden tiger from 2012 is still improving in smell and taste in a very positive way. delicious orange flavored cigar box smell coming off the bag. totally unexpected smells. the taste is very smooth and melded like a good cigar is after proper aging. the colors are turning very nice as well.

:)
 

greenops

Member
Hey Granger, thanks for your input. Though I don't think the temperature alone is causing the evaporation because I know that outdoor grown weed in a warm or hot climate can have some funk too. The sun may have a better light spectrum that helps boost terpene production.

Hi OO, yes my air cooled hood is sealed by glass, not sure if silica glass but i guess not. Even with glass, do u think the MH can still have a positive effect in terms of terpenes production, as opposed to using the HPS all the way? I know the type of lights they use for reptiles in terrariums would be more suited for the job, however those lights require more space (as they're only supplemental) and have to be nearer to the plants to have some effect. That brings heat and also they are a bit too pricey. I know all too well what u mean with the Skunk #1. That was the first strain I grew, but I'm sure i made some newbie mistakes as well.

Hi Iddit, nice looking buds man. I believe u when u say buds grown under the sun have a better taste and smell.
I grew some seeds for fun on my balcony one time, the same seeds I've grown indoor too. The outdoor buds were smaller but smelt much better. That's why i believe that lights play an important role in this.
 

Granger2

Active member
Veteran
I didn't say it was temps alone. The sun has the ideal spectrum, in particular, lots of UV. Good luck. -granger
 

Piff Rhys Jones

🌴 Hugging Trees 🌴
Veteran
Hi greenops, I think the problem is simply down to the strains/phenos. In my experience lots of plants will smell and look nice but this smell doesn't always translate into the flavour.

You may get lucky and find a special pheno with a strong taste but in my experience more often than not a lot of searching will be required when selecting from seed to find the super tasty plants.

Peace
 
A

acridlab

Hey, think I can help a lil, everyone has great input,, first off, yeah, good genetics are key.. if u have a true dank plant, it's hard to ef it up.. but I can say that certain things in ur grow can makes flavors/aromas very good or very bad... radient heat on ur buds from improper cooling definitely make a difference. When they say 75 at canopy, they aren't b.s'n.. best thing u can do to work on this is getting a infra red thermometer, some are priced as low as 40 bucks.. they're awesome..Mh or cmh really helped me, even with glass, had a good run with 1000 watt horti mh.. but I prefer bare bulb. I'm not trying to sell anything but I love the combo of 1000 watt ushio hps in air cooled hood, with the Phillips master color 400 watt cmh dropped in vertically,, my best results ever. I have tried 100 watt lizard uvb bulbs, they produce alot of heat an weren't a help in my situation..., Another thing that helped with aroma is hanging the plant whole vs. Cutting up n hanging tons of buds on a line etc..I used to try ice and dropping temps,, it might help some, but I never saw much difference, just more work.. oh, I do believe in chopping during lights off.. basically if u have good genetics and good temps, good lights, good food, "and not too much", you can chop it, hang it for 5-9 days, and it will be dank and smoking good already..I stay away from genetics that you have to jar and cure and burp and wait and do all of it over again, praying it starts to smell good..so. yeah,, good genetics are pretty important
 

blastfrompast

Active member
Veteran
Temps are a huge factor..

I like to run my rooms 78' or less during the light cycle, and drop them down 20 degree's at night...58-60 seems perfect. It hurts my yield a bit, but I look forward to winter buds...I crop better in the summer when my night temps stay around 65'...but winter tastes better, and are stinkier.

strain matters, but temps seem to be a big one..

I can't tell if the cooler temps affect the potency as it all gets me blasted...
 

greenops

Member
Thanks for all the contributions guys. I'm starting to get a better picture.
Just funny how before when I questioned my high temps, i was told numerous times that lower 80's is still within range.

I measured different spots around the canopy. The hottest part I measured was 78F.
That's when I set my ballast to 600w. But when I dim it, I can easily get it down to 73F max. So I'm wondering if I should just dim the lights to 400w the entire time? Will there be a significant loss in yield? I've read somewhere that in a tent like mine, 1m x 1m area, 400w is enough to meet the plants demands.
 

ChaosCatalunya

5.2 club is now 8.1 club...
Veteran
For the last 2 weeks, turn off half your lights and raise the rest, lower temps at the top of the plants (will, if anything) make a tastier crop and you loose no real yeild, the basic structure of the bud is made by then, it just has to mature a little. In Nature, Autumn, you get much lower light levels towards the end of flowering.

If you are cooking the buds enough to bake a lot of the aromas away, you are probably (variety dependant as is most info) going to see new flower growth spurting out of the bud tops from the heat stress.

Almost all the underwhelming bud I have ever seen has simply been taken too early, resin glands and the terpenes neeed to be properly mature.
 

Dropped Cat

Six Gummi Bears and Some Scotch
Veteran
Humidity? I noticed keeping closer to 50% is good for my ladies.
Temps around 65-75F.

Some Zamaldelica by Ace. Interesting profile, carrots and sweet mangoes.

picture.php


12 months in the jar, and very smooth. Grown micro style with maxibloom, the right way.
For me and mine.

Good thread.
 

shaggyballs

Active member
Veteran

greenops

Member
Thanks Shaggyballs, i got some reading to do.

Hope to read more ideas on how to increase terpenes.
Especially from those who switch from HPS to MH at the end, as this seems to be the only thing I can do at the moment, while keeping my temps under 75.
 

shaggyballs

Active member
Veteran
It is funny I do mh first to reduce stretch then hps last for the red end in harvest!

But keeping the heat down more important I think 80 is ok 75 is better.

Also use your adjustable ballast for lower wattage during ripening after they are done with bulking up.

Also make sure your thermometer has a max option so you can see what the highest temp was while you were away.
 
B

Baked Alaskan

Lots of great info here.

One thing I noticed about taste and smell is time of harvest, just a few days makes a difference. the strain I grew the last few years was tinny, metallic and somewhat rancid before 60 days but after 65 or so the taste really mellowed. Still not the best tasting but not tinny or metallic.

Grew this strain for 2 1/2 and this was the deal every time, even when others grew it.
 
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