Marijuana flushing—it’s not that hilarious Cheech and Chong vinyl album skit when stoners desperately flush weed and other drugs down the toilet as police kick down the door. Instead, marijuana flushing is a process you do in the last 5-10 days of bloom phase. It’s an important part of finishing and quality-enhancing your crop, whether you grow in soil, deep water culture, coco coir, rockwool, grow stones, aeroponics, soilless mix, and other marijuana growing systems.
Flushing marijuana is important because it purges nutrients salts and other materials from marijuana plant tissues in the last days of bloom phase. Marijuana stores these materials very efficiently because it’s a bio-accumulator plant that takes in and stores a disproportionate amount of what’s in its root environment.
Some of what it stores in its plant tissues are nutrients, heavy metals, and contaminants. These materials, especially heavy metals and potentially radioactive elements like phosphorus, pollute your crops and can affect your health and taint your marijuana consumption experiences. In fact, cannabis is so good at sucking in materials from the root zone that it’s used as a repair plant to remove heavy metals and other toxins from the soil.
Unflushed buds don’t smell or taste good. They taste like chemicals. This can happen whether you grow organic marijuana or with synthetic hydroponics nutrients. Unflushed buds are often hard to combust even if the buds are dry. And if the don’t easily burn to a white ash, it means your crops aren’t flushed properly.
One thing that concerned me was when I heard a hydroponics scientist explain that many fertilizers pollute crops with heavy metals. This can cause serious health problems.
Want to get radioactive? Marijuana fertilizers loaded with phosphorus in base nutrients and bloom boosters can load your plant tissues with radioactivity. Phosphorus glows in the dark, remember?
Marijuana Flushing for More THC & Terpenoids
You hear a lot of arguments about marijuana flushing. Some people claim it’s not necessary. Or that it’s only necessary if you grow using synthetic hydroponics nutrients.
I’ve researched the arguments and the effects of flushing, and had my own doubts about flushing. But my research and experience has proven to me that flushing is necessary and useful in ways most growers don’t yet know.
The most important and least known benefit of flushing happens because flushing deprives your cannabis plants of nutrition at the end of bloom phase—and this deprivation spurs your plants to make more cannabinoids and terpenoids as a stress response.
The other benefit is your crops burn up all the nutrients and other materials on board during flushing, resulting in clean buds with better taste and scent and no polluted tissue.
Timing your flushing is tricky, and involves having general skills in harvest timing. I’ll be providing other articles on harvest timing but as regards flushing, the rule is to set a firm date for harvest, and then 5-10 days before harvest you stop all nutrients feeding and give your plants only pure water and a flushing formula.
The preferred flushing formula of professional cannabis growers is called Flawless Finish because it’s the only flushing formula made specifically for marijuana. It has special compounds called chelates that bind with crop contaminants and remove them from plant tissues and the root zone. It also contains tiny amounts of specific nutritional elements that support cannabinoid and terpenoid formation and bud weight increase.
I recommend always using reverse osmosis water in your marijuana garden, and at flushing time, that’s especially important. Most water contains calcium, iron, and other elements, and it can also contain poisons and other pollution. Reverse osmosis water is absolutely pure, and adds no contamination to your plant tissues.
You should also do mini-flushes during your crop cycle. Depending on what kind of nutrients you’re using and what’s in your root zone, flushing is useful if you’ve overfed your plants, used inferior nutrients, and to clean out grow phase fertilizers when you transition to bloom phase.
When I see signs of leaf tip burning (an indicator of overfertilization), I do a mini-flush. How to do it? Use Flawless Finish as directed but only for one or two watering cycles, and not for more than 2-3 days.
Mini-flushing is only useful in grow ops with solid material in the root zone such as rockwool, soilless mix, and coco coir. If you’re growing pure hydroponics such as deep water culture, aeroponics and NFT (nutrients film technique), there’s no solid root zone media to flush. In pure hydroponics systems, you still do your flush at the end of bloom phase.
Soil is the hardest to flush. Once it accumulates an excess of nutrients, it’s very hard to purge them without creating a waterlogged condition that drowns roots.
Now you know the real deal about cannabis flushing. Done at end of bloom phase, it creates a plant stress response that results in more cannabinoids and terpenoids, and it cleans your buds so they taste, combust and vape better.