What does it mean to FLUSH exactly??

[DirtyCoconuts]

So i have seen this term used a lot in discussing SH and i was wondering, specifically, what it means and how it is achieved.

I took the term to mean, fully filling the SH container with the drain holes covered and then releasing the water to its normal level.

i have seen some folks use the term to describe FLUSHING in the sense of normal potted orchids where you just run a lot of water through the growing area

i also wonder how much water is needed to FLUSH the container. if i grow in 1L containers and the res is 1/3 of a liter do i need to fill the whole container to flush or just volume equal to the reservoir in order to allow for the replacement and exchange of water, gas and nutes?

lastly, can a flush be accomplished with fert water or is it by definition, only RO or rain water?

thanks!

[Ray]

To me, "flushing" is the action of pouring a solvent through the potting medium so that it carries away plant wastes, chemical residues and medium decomposition products, if any.

That simply means "pour it on and let it drain", no matter the growing technique used.

How you do it and what solvent you use determines the efficacy.

Pure water, of course, will be best, but that doesn't mean that tap water or dilute fertilizer solutions don't work.

Using a large volume of water relative to the pot size improves the cleansing action.

Flushing a pot containing moist media improves the cleansing action. Letting media dry between waterings decreases the cleansing action of a flush.

In S/H culture, closing the holes, then opening them to let it drain decreases the cleansing. Think about it: the medium and reservoir are full of the stuff you're trying to get rid of. if you run a lot of solvent from the top and let it freely drain, the fresh liquid tends to push the old stuff out. If, on the other hand, you plug the holes, you are allowing the "crud" to contaminate the "fresh" liquid, so it is absorbed by the medium and when allowed to drain, the reservoir contains diluted crud rather than fresh material.

That is also the reason top-down "shower" watering is better than a periodic soak in a tub in traditional culture.

[rbarata]

I think I flush in every watering.

[WaterWitchin]

What Ray says. Don't cover the drain holes. Let water pour in through top until it reaches the point of full; meanwhile, water is running out holes and flushing the cooties out. Just putting enough water in to fill reservoir is only "topping up" your drink.

Pretty sure Ray's method is flush each time you add water. Mine is top up occasionally if needed, then flush once a week. The deal is to keep the dry line as high as possible, regardless of method.

[DirtyCoconuts]

Got it. That is a lot more water to use, but also makes sense.

Thanks all

---------- Post added at 11:37 AM ---------- Previous post was at 11:33 AM ----------

Hmm so this really adds to the size of the hole discussion. Small holes means more time in the soak and less water is used but also a less turbulent exchange.
A larger hole means a lot more water and a more turbulent exchange but less time in the soak as it flows out almost instantly.....

[WaterWitchin]

I go for a quarter-inch bit regardless of plastic, glass, ceramic. Seems about the right amount of action going on... at least to me. Larger holes, more stopping up with LECA. Smaller holes, doesn't drain fast enough to suit that churning action.

It depends also on how one waters in other medium whether it's more water or not. When I grew in bark, I used about the same amount of water that I use now. But I always used a flushing method, regardless of medium... even with house plants in potting soil.

---------- Post added at 10:54 AM ---------- Previous post was at 10:46 AM ----------

Speaking of which... I have a caveat now on only putting one hole into glass containers. My opinion before was only one hole was necessary unless one was watering automatically, as Ray was when he first started using the method.

The point being... if you're present when watering, you'll notice whether the vessel is draining or clogged.

The caveat.... I was taking all orchids outside in the summer. (Won't be doing that anymore..) This year I found several that kept clogging the hole when it was raining for a day or two. I'd come out to find lots of LECA on the ground, and a plant floating in its container. Have to unclog the hole, and top up with LECA again. Seemed to happen more with two or three I had in large containers of a certain shape. If I continued to use those containers in an outside setting, I'd be drilling a second hole in them.

Just thought it worth sharing...

[Ray]

I always go for two, 1/4” holes, side-by-side, no matter the size of the pot, and I flood the crap out of it - sometimes twice - at every watering.

[DirtyCoconuts]

Hmmmm the thing I was comparing was the hold the hole and fill vs the free flow. Not comparing to other watering methods.

I don’t know if I like the small holes as more drilling in glass is just more to break. I might do the cover the hole method I have been doing and then make a free flow flush once a week

[WaterWitchin]

Originally Posted by DirtyCoconuts

Hmmmm the thing I was comparing was the hold the hole and fill vs the free flow. Not comparing to other watering methods.

I don’t know if I like the small holes as more drilling in glass is just more to break. I might do the cover the hole method I have been doing and then make a free flow flush once a week

I think flushing once a week free flow is fine DC... and watering however you water the rest of the time. I personally just top up until water starts to come out holes rest of the time.

Small holes? if you get much bigger than that, the LECA will just roll right on out won't it?

---------- Post added at 11:41 AM ---------- Previous post was at 11:40 AM ----------

And yes, I'm still not drilling the two holes in glass. Just pointing it out that occasionally you have one that needs two if they're either auto-watered OR out in the rain... I think it has to do with the shape of the vessel.

---------- Post added at 11:43 AM ---------- Previous post was at 11:41 AM ----------

PS I mean quarter inch diamond drill bit for glass... a quarter inch drill bit in plastic comes out a bit smaller, so I use a larger bit.

[Fuerte Rav]

Originally Posted by Ray

I always go for two, 1/4” holes, side-by-side, no matter the size of the pot, and I flood the crap out of it - sometimes twice - at every watering.

Wish I'd seen this comment before I prepped my S/H pots. I get water everywhere, every time I flush, no matter how careful I am.