Flushing your plants in the last two weeks of a grow is one the most common pieces of knowledge when it comes to pre-harvest time.
So is flushing your plants before harvest a good idea? Yes. But not for the reason that most people think…
Any time you feed your plants, they intake nutrients which - in too-high amounts - are not able to be used by the plants and therefore can add a 'chemically' taste to your buds. Flushing in the last two weeks gives your plant a chance to “drink water” without extra minerals to further alter the taste. It also clears out any build up of excess minerals or nutrient salts in your medium (such as coco coir, or water for DWC).
However, flushing does not "leach out" nutrients/minerals that are already in the buds. While your plant can use up extra stored nutrients in the leaves of the plant, this does not remove a "chemical" taste from your buds if you've provided too many nutrients throughout the flowering stage.
Many people believe that flushing with plain water takes nutrients (and thus bad taste) out of the buds, in a sense, returning them to their ‘natural flavor’. Unfortunately, this just isn’t the case.
When it comes to ensuring good taste and smell of your cannabis plants, an ounce of prevention is worth a pound of cure. Instead of relying on the flush to prevent extra nutrients from being stored in your buds, it's better to avoid ever giving the plant more nutrients than it can use in the first place. That means keeping nutrient levels as low as you can throughout the grow while preventing nutrient deficiencies.
