Editor's Note: Info is for those that grow in soil.
When I first started to grow and it came time to flush which is before you cut down your plant(s), I didn't really know wtf I was doing. I knew a 5 gallon pot needed to be flushed with 15 gallons of water so like an idiot newb, I watered it with 15 gallons all at once! Doh. Drowned it. It didn't die or anything and it wasn't all THAT wrong. Fortunately my growing medium was capable of allowing it to drain good.
Now, three years later, I still give it the 15 gallons but spread it out over a period of 7-14 days. I prefer to flush for 14 days, I'm pretty anal about flushing I want nice clean smoke!
The reason flushing is a must at harvest is you need to leach metals, calcium, sodium, chlorides, sulphates and many other compounds which can build up in the soil. If you don't flush your smoke will crackle & pop when lit, taste harsher than it should & won't burn to a white ash but black, which of course, reveals that it wasn't flushed properly. It also can cause some serious coughing. You don't want to be smoking your nutes, that's just gross!
Not only should you flush your plants at harvest, you need to flush them at the least once a month in order to get rid of all the accumulated undesirables. You don't need to use 15 gallons for the monthly flush, just make sure you get at least 10% runoff or 10% of the water that goes in comes out. You can also flush to fix a nute burn.
|I use FloraKleen when I need a quick flush, 7 days.|
If I don't have to flush in a hurry I use RO (reverse osmosis) water with a low level nute. I use Infinity by Aurora. You want to give it some nutrition when flushing and this product at 0.5–2.5–1.5 is perfect!
Click link to visit Aurora Innovations
Soul Synthetics Infinity catalyst is a complex blend of powerful organic compounds combined with choice plant nutrition. Infinity is specially formulated to increase vigor and prevent micronutrient deficiencies common in fast growing and heavy feeding plants. With its proprietary blend of distinct ingredients, Soul Synthetics Infinity can be used with any nutrient program for increased micronutrient uptake and with any base fertilizer line as a powerful plant nutrient supplement. Soul Synthetics Infinity catalyst is derived from Soy Protein, Kelp, Agave, Yucca, Molasses, Pure Sugar Cane, Magnesium amino acid chelate, Calcium amino acid chelate, Iron amino acid chelate, Bamboo Extract, Green Tea Extract, Grape Seed Extract, and Humic Acid derived from Leonardite.
Here's a great video on how to test to see if your cannabis was properly flushed. I love the ash test and thats how I judge my own smoke. White ash is what I strive for & why I flush so well.