Have you ever coughed so hard after taking a hit that you feel like you’re on the verge of bronchitis? Or what about rolled up a doobie and after toking on it realized you have a fertilizer taste in your mouth?  This could be because you didn’t flush your plants before harvest.

Flushing your marijuana plant is kind of like a giving it a detox from all the nutrient salts and nourishing chemicals that may have stored in your cannabis plants’ tissues. Your plant stores these nutrients in their leaves in case they don’t get fed again for a while. Since we’re all good loving plant parents and without fail (if ur smart that is) continue to feed them, they don’t actually need all the stored up food. This is where our loving care comes in, because they can’t get rid of it without us. Your plant's growing medium, the soil, needs to get flushed to get rid of the excessive nutrient buildup and then- and only then- will your plant use up the stored nutrients when it’s not fed more incoming nutrients. However important the fertilizers are, it is important to clean up after a few months of diner -so to speak :) because this nutrient buildup is what causes your smoke to be harsh and bad tasting. Contaminated buds contaminate both your health and high; you’ll be smoking weed along with whatever food it was given. Your poor lungs will suffer! Because the bud doesn’t light properly, you lose sufficient combustion and full decarboxylation (when THCA converts to THC).

Smooth and tasty

After buying some bud you can tell if it’s been flushed or not simply by lighting it up! If the joint is hard to light and the ash is dark it’s probably not been flushed. Your ash should be white-gray and inhaling should be like it’s meant to be- ,Mmmmh smooth and tasty.

You’re going to want to wait to start the flushing until it’s the early end of the harvest window; around the time when you can just practically harvest it already. It’s a big mistake to start flushing too early as it stunts the growth because the buds are not getting the right amount of nutrients to develop properly.  If it doesn’t get the right amount of nutrients during the most critical parts of the flowering stage then you’re putting the quality and potency at stake. If you’re too hasty with starting the flush, and realize afterwards that your plants still need a couple of weeks to mature fully, then you have a situation on your hands. You would have to decide whether to harvest it early, continuing to flush (which can cause nutrient deficiency), or going back to using nutrients.

Pump and Drain

The entire flushing will take 2 weeks if you want it done thoroughly, but if you don’t think you need to do it for so long, aim for at least 10 days. Let’s first look at flushing when you are using soil as your medium. First off, put your pots in a draining tray to catch the runoff water. You can also place them in a large enough sink if you have it. Then, using pure water with a pH of from 6.0 to 6.8 water your plants with a few gallons of water. Use a shop-vac to suck up the water from the draining tray. Avoid letting your plant sit in the runoff water for too long as the nutrients can get leached in again and that will just make the whole process pointless.

The idea stays basically the same if you’re using a hydro setup. Unplug your water pump and drain all the water. After detaching the hoses from the bucket, sterilize your system. Now you can add the water back into the reservoir. Don’t forget that you water should have a pH of between 5.5 and 6.5. Now you can reattach the hoses and let the water circulate for 2-3 hours. Next, you should repeat the process of draining your system and adding new water.  Allow that water to circulate in your system until the following day.  Replace the water again for the 3rd time and keep this water circulating for the next 10-14 days.  Keep an eye on your pH throughout the whole thing.


If you go through with flushing your plants before harvest you will certainly thank me; toking on your clean and wonderfully self-grown bud will be smoother than hot butter… Enjoy!

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