Sunday, March 22, 2015
Dear Fellow Grower,
In today's issue...
"Iron rusts from disuse; water loses its purity from stagnation... even so does inaction sap the vigor of the mind."
~ Leonardo da Vinci
What is Flushing?
Flushing is free and easy technique that may improve the quality and smoothness of your cannabis buds. Sounds good, right? Of course it does! But growers must also be careful with flushing before harvest because if you do it too early you can actually hurt your quality (and reduce your yields)!
The process of flushing involves giving your plants just plain water (no nutrients) for a period of time before harvest. An example of flushing would be if a grower gave their plants just plain (pH’ed) water for the last 2 weeks before harvest.
The idea behind flushing is to let the plant “use up” all the nutrients contained in the plant and buds, so there isn’t any left over after harvest.
So in soil or coco coir, the grower would give the plant just plain water for days or weeks before harvest time. This lets the plant use up the nutrients in the soil/coco, and then theoretically start leaching extra nutrients from the buds.
In a hydro or DWC setup, flushing is even easier. The grower simply replaces all the water in their reservoir with plain water, and the plant doesn’t have access to any nutrients available except for what’s already in the plant.
Flushing is Giving Plants Only Plain Water For Days or Weeks Before Harvest
Is Flushing Important?
I used to think that flushing wasn’t that important. I'd still do it most of the time based on good practices, but other times I'd cut the flush short. One of the most common reasons growers tell you to flush is that not doing so affects flavor. I’d tried flushing and not flushing, and I personally couldn’t tell any difference when it came to smell or flavor.
In fact, I got lots of compliments on the taste and flavor of my buds. My unflushed buds didn’t have a “chemical” taste like others have warned of, and I figured the need to flush was basically a growing myth, or something growers should only do if they’ve given their plant too many nutrients.
I became the worst thing a grower can be - a "theory crafter" - someone who bases their ideas on a theory or idea instead of actual evidence or experience. When it came to flushing, I told myself, “How could the plant be removing nutrients out of buds, anyway?” I also figured that a flush wasn’t needed for my grows since I kept nutrient levels low throughout the entire flowering stage. I thought maintaining lower levels would prevent any type of nutrient buildup (so to speak) in the buds.
I still don’t truly know about the science behind flushing or why it works, but after my last grow, my experience has completely changed my opinion on flushing. For my last grow, I harvested different plants at different points in the flushing process.
While this was definitely not a honest-to-goodness scientific experiment since I was growing different strains without controls, my experiment was enough to change my mind.
I grew three plants - I had one plant I didn’t flush at all, one that was flushed for a couple of days, and one that got flushed for a little more than a week.
My fellow grower Sirius Fourside grew two plants at the same time and flushed his for 2 weeks.
We both used the same nutrients (General Hydroponics Flora trio) and the same type of grow light (HPS).
So how much of a difference did flushing actually make?
It seemed pretty obvious that flushing made a big difference. The longer the plant was flushed before harvest, the more “smooth” the buds were when smoked. When I say smooth, what I mean is that the smoke was less likely to irritate the back of the throat or lungs.
The plant which wasn’t flushed at all had buds that were particularly harsh, and caused me to cough every time I smoked it; not that the quality or taste suffered. The ones that were flushed for longer were just plain better.
Luckily, you can partially fix harsh buds by curing them for longer - giving buds a little extra time in curing jars will reduce the harshness dramatically, but why not try starting with smooth buds from the beginning?
The two plants flushed for two weeks yielded buds that came out buttery smooth, not irritating the throat at all.
In conclusion, in our insanely informal experiment, longer flushing seemed to create smoother buds, at least up to 2 weeks.
As far as we could tell, the taste and smell seemed completely unchanged, so I stand by the fact that, at least in our experiments, flushing didn’t seem to have an effect on flavor/smell.
So does that prove anything? No. But it is enough evidence to change my opinion and I’ll be doing at least a 2-week flush on all my future harvests. There doesn’t seem to be any true downside to flushing (as long as you avoid common mistakes like flushing too early) and the potential benefits are worth it!