NEVER!!! (imagine it like a battle cry... not like savage viking... more like schoolyard tackle football)
I stop feeding... well I don't really feed much at all... I mix my soil to get my plant through veg and then top dress for bloom. I sometimes add a little something to my watering... if I feel like it... tiny amounts... so yeah, I use only water for the last idk, week? before I stop watering altogether. But even if i was feeding them regularly I wouldn't call this flushing, more like, not spending more nutrients on a plant that's not gonna use them.
What are you trying to accomplish here? I mean you can flush the soil but not the plant, and you don't want to flush out the soil unless there's a problem. The soil is supposed to hold the nutrients in suspension for the roots to absorb... its like a buffet (to a degree) you make as much available as possible, and the plant will take what it needs as it needs it... As long as your quantities/ratios are right for the amount of soil and the plant you have, you're never trying to get the nutrients out of the soil... you worked hard to get them there, why flush them away?
One reason roots grow is because they are "eating" their way through the soil... absorbing the nutrients in proximity to them, and reaching out for more (they're also looking for more oxygen and water... so yeah, roots as mouths... wormy mouths). They're not just soaking up everything in the pot all at once.
I think you need to rethink your approach to feeding (in dirt... what you're doing sounds like something a hydro grower might do).
