How and when to flush?

hey guys, kind of a noob here but just have a general question. My plant is 4 weeks into flowering and doing well, feeding 1/4 strength FF trio every other watering. However I heard Fox Farms recommends flushing every 4 weeks, should I do that or should I just flush 2 weeks before harvest like they say to?

Also, what is the best method of flushing I should do? I’m not really sure how to go about it.

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At 1/4 strength I would think you would be fine with just the last two weeks of flushing. When you start your flush use nothing but clean water. I like to shoot for a ph of 6.3.


There are a lot of discussions regarding this matter (a shiiit load). The way I understand it is with FFOF fox farms says to flush WITH SLEDGEHAMMER every 4 weeks or so to flush out built up salts from neuts. They say use sledgehammer with double the normal amount of water you use to feed ie: I water 2 gal each feed so I use 4 gal with sledgehammer pour thru and done. After just continue feeding as normal. The final flush before harvest is all together different. I will let someone else go over that as I’m not sure about it.


Ah I see. I just fed it again today as per the usual schedule and the runoff ph is at 5.2. does this mean I should flush it with sledgehammer? From what I understand I think you’re supposed to wait a half hour or so after using sledgehammer and then give it a few gallons of regular ph’d water.

Do you think I should do it next watering?

Nope the procedure above is it. After the flush when it drys out water or feed normally. You dont rince the rince.

Assuming no serious issues, the final flush is nothing more then discontinuing feeding and giving it water the final two weeks