In part 1 of my series “Things I Wish I Knew When I Started Growing Cannabis“, I covered how cannabis is an easy plant to grow, that many growers are giving their plants too many nutrients, the importance of learning multiple plant training techniques, and why it’s great to grow multiple plants.
In part 2, we’re checking our sources, diving into some controversy, learning how to not lose our entire grow, and how to achieve that perfect elusive harvest.
Reading General Gardening Books/Advice vs. Cannabis
Here is a place where I both did things right and didn’t. When I first started growing cannabis, I read everything I could on cannabis websites and forums. There is a god-awful amount of misinformation there, and I have fallen victim to it one too many times. Though, if you know where/how to look, some of the information is priceless.
While I had never grown anything indoors before cannabis, I grew up on a farm with a rather large outside garden with various crops. This helped me work out those who knew what they were talking about and those who didn’t. Everyone who knew what they were talking about had one big piece of advice. Stop reading only cannabis literature and pick up general gardening, botany, and horticulture books.
It wasn’t until this year that I finally decided to digitally crack open a very famous cannabis book. It was awful and full of misinformation from saying plants don’t use green light to nutrient recommendations that would make Momma Nature cry. I’m all for making mistakes, especially if they occurred because the technology or studies weren’t there at the time. But to my knowledge, the author hasn’t corrected much of the misinformation with their revised editions.
I went from thinking light leaks means light escaping from the grow tent to building my lights. Life’s a journey, you know? But you’re probably smarter than me and know that light leaks refer to light getting inside the tent when the lights are off. If you are like me, just hey, look where I am now!
Light leaks aren’t a matter to take lightly — hey oh! They will seriously mess up your cannabis plants. In fact, the only time I have ever lost a cannabis plant from a grower’s error was from light leaks. It turned one of my plants into a hermaphrodite who went and pollinated the other two. This was early into flowering, and I lost my entire garden. That stung!
We aren’t sure just how sensitive cannabis is to light leaks, but there may only be a few, if any plant species, more sensitive to it. This means keeping all light out of the tent during the dark period. Check for holes in your tent and make sure the room the tent is in is dark. I go so far as to keep any electrical equipment with indicator lights like power surges out of the tent. I cover the lights over with tape since it sits right outside the tent’s intake port because you truly can’t be too safe here.
End of Harvest Myths
End of harvest flushing and 48hr darkness; the topic I love to hate.
I’m not going to dive into this topic too much. I believe that if you make a claim, you need to back it up, not the other way around. Though I’ll likely make an article that takes an in-depth look into both of these issues because I know it’s a very passionate subject for people on both sides.
My first grow or two, I both flushed my plants the last two weeks and gave them 48 hours of darkness before harvest. I honestly was never sold on these ideas because they don’t exist outside of growing cannabis. For me, it creates the notion that cannabis is a special plant or that the agriculture industry doesn’t like maximizing profits.
Plus, I have never been able to find research to back up the claim they improve aroma, potency, yield, etc. Yes, I am aware of the few “studies” out there, but they are riddled with poorly controlled variables or completely lack any credentials. In fact, I have only found research to rebuke these claims.
I think the idea of flushing has taken hold for several reasons. First, flushing excess water through media helps breaks down soluble salt buildups and removes some excess nutrients. Helpful if you’ve accidentally been giving too much. Second, I think end-of-harvest flushing caught on because so many cannabis growers are feeding way too much, and If they continued to feed those levels to the end, they may end up with foul-tasting flowers. Third, there is a “resource conservation” aspect to flushing that may have big implications for commercial operations. Fourth, you’re likely not hurting yield much, if at all.
But, the answer isn’t to do that end-of-harvest flush where you run excess clean water for the last two weeks prior to harvest. Let’s look at studies.
Rx Green Technologies found flushing had no real effect whatsoever. Under the “scope”, it didn’t improve flower content, potency, aroma, smoothness, etc. in any sense. But didn’t hurt them either! Jonathan Stemeroff came to a similar conclusion in his study, “Irrigation Management Strategies for Medical Cannabis in Controlled Environments“. Commercial operations should take note of this study, in particular, as Stemeroff reduce the watering amount by 25-45% for the last two weeks without affecting yield.
So you may be able to save money by removing nutrients early, but on a small scale, that’s barely anything. Plus, new and home gardeners would be better served learning to feed less in general. Then, many think that end-of-harvest flushing entails watering heavier — makes sense as the one thing flushing does for sure is stripping the media of excess salts. But Stemeroff’s research shows we want to do the opposite and reduce the amount we water. Then, jumping back to the Rx Technology study, they did a blind taste test. Their test panelists preferred the unflushed flower the most. I honestly think that’s happenstance; I’m just ruffling feathers at this point.
So what’s the answer?
Right now, I want you to try feeding a milder nutrient solution throughout the flowering stage, keeping plants medium to dark green. Then start tapering off both nutrients and potentially the amount of water the last week or two — water thoroughly 24hr before harvest to extend drying time. Avoid the classic “fade”, but bottom yellowing leaves are likely A-OK. While watering less is likely safe and helpful for the environment, right now if you’re a home grower, don’t feel pressured to do it as water stress can reduce cannabinoid content.
This will keep the plants in a maximum productive state to the end without causing an undesirable taste/aroma. While extremely rare for cannabis growers, you can under-fertilize without seeing signs of nutrient decencies. Called “hidden hunger”, if you notice your buds aren’t filling out as usual and your plant isn’t dark green, slowly increase nutrients levels.
Prolonged Darkness Before Harvest
When it comes to giving your plants 48-72 hours of darkness before chopping them down, I’m very skeptical. It could be a way for commercial operations to save money, but unlike with “flushing”, there’s no research to say.
I do think harvesting during the dark period may be good practice because some terpenes are volatile to light. Anecdotally, I’ve found that non-phosphorus bloom boosters that contain proteins help increase both the number of trichomes and smell, as well.
If you, for sure, want more THC and other secondary metabolites, you should focus on getting the correct amounts of blue and UV light into your grow room. A silica additive is greatly recommended as well, as the trichomes are filled with it. Last, according to recent research by Utah State University, we may need to reevaluate our temperatures as they’ve noticed a 50% decline in cannabinoid content when moving crops from 73F to 85F. As such, you may want to aim for keeping temperatures under 80F with a greater focus on maintaining the correct VPD to ensure healthy transpiring plants.
Importance of the Harvest
Another reason I’m not a fan of end-of-harvest flushing — even if a week or more may not hurt yields — is because it often tricks a grower into harvesting too early. Even after all these years, I’m not 100% comfortable calling a harvest date until about a week out. So many little things can throw off my estimates before this point.
The key to the harvesting and drying/curing process is patience.
To know when to harvest, monitor both the hairs and, more importantly, the trichomes on the actual flower/calyx/bud. DO NOT go by the trichomes on the sugar leaves. For some strains, the hairs turn orange and curl in early, so be careful. I pick once the trichomes on the upper buds have about an equal number of amber and clear trichomes — about 80% cloudy. I’ll harvest all at once, meaning the trichomes on the buds farthest from lights are more clear than amber. I like the perceived range in effect this causes, but you can harvest slowly over days so all the trichomes can mature.
A slow dry/cure helps remove all the harsh flavorings we don’t want in our buds, like the sugars and chlorophyll, while improving the bud’s integrity. If you dip your buds past the 60% humidity marker too soon, drying/curing can come to an end, leaving those nasties stuck in your bud and our trichomes at risk. The true point of no return is debated.
For the first two weeks definitely, stay above 60%. After, I stay here because my humidity outside is usually pretty low, and I’ve never seen mold issues. Some, however, may want to drive their humidity to 55% then maybe 50%. I like drying for at least 7 days before jarring. The buds should feel dry on the outside and the stems near their cracking point, but still flexible. I’ll burp the jars at least once a day for about two weeks after.
I found the key to getting long dry/cure times is separating only the biggest stems from each other, leaving the mini shoots on them. Then remove the fan leaves, but only remove the very tip of the sugar leaves, which you can take completely off — if desired — before jarring. I would remove most, if not all of the stems, before jarring as well. I start my tent around 70% humidity and keep temps around 65F. I run a small fan that’s pointed underneath or away from the hanging buds. Direct airflow from a fan will dry those suckers out way too fast, but airflow is critical.
While cannabis isn’t a special plant, growing it sure is, but nothing can kill that joy faster than worrying yourself sick over your mistakes. In most cases, your mistake isn’t a big deal, often it only becomes a big deal when you freak out over it and do something irrational. Everyone makes mistakes, but it’s learning from those mistakes that separate the master growers from the novices.
Looking to sound off about my advice or felt I missed a common mistake other growers could benefit from? Let me know in the comment section.