Cannabis Flushing – After looking into the study and writing up our previous blog Cannabis Plant Flushing – Is It Really Necessary? We decided to ask growers with plenty of real life experience about whether they flush or not and the reasons behind it.

We headed over to our favourite forum Growroom420 to see what some people had to say.

In todays post:

• Introduction to Growroom420
• Questions asked about Cannabis flushing
• Responses from GR420 Members
• Deep Dive Response From Keeno – GR420 Admin
• Our take on the results

Introduction to Growroom420

Growroom420 is a online cannabis growing community for those looking to learn, share and take part in a community of people with similar interests. GR420 has grow diaries, tips for finding solutions to cannabis deficiencies, info for learning how to grow cannabis and much more.

As well as this they also run loads of competitions exclusively for members. This can be for anything from seeds, stickers and other accessories all the way to grow lights. To be part of any of the competitions you just need to be a member of the forum – if you aren’t already we would advise signing up!

We love working with GR420 – it is a really friendly community who welcome new members with open arms. As well as all things to do with Cannabis, GR420 also offers spaces for members to discuss similar interests and general goings on in the world.

Questions We Asked About Cannabis Flushing

Do you flush before harvest?

If yes, When?

Why or why not?

In your opinion does it change the flavour, burnability, potency or smoke smoothness?

Responses From GR420 Members

“I’m a soil grower so I don’t flush, but I do cut down on organic nutes and try to coast to the finish letting the plant get a bit hungry and hopefully use up its nutes as it finishes.”

IMO – GR420 Member

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“I do not flush in soil, in a neutral medium and in hydro I do flush. In coco or the like 2 weeks before harvest, in hydro I feel a week to 10 days is sufficient.

When I do I want to remove any chemical ferts, and make the plant use up what stored nutrients it has in it.

This gives that nice “fade” lets the plant know it’s time to make that last push to swell. Gets rid of more chlorophyll giving a less harsh smoke I think it also enhances the flavour, and promotes better burning.

The reason I don’t in soil is that I recycle my soil so a plant comes out a few amendments go in and quickly a new plant is potted up into that soil.”

Sage – GR420 Member

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“Do you flush before harvest? – I’m a coco grower for the record. By flush I’m assuming you mean 3 times the volume of the pot I’d be growing in. So I don’t “flush” I plain water feed for 7-10 days before I intend to chop, by feed I mean I am giving it the same amount of water that I would in a feed mix.

If yes, When? – When I see over 80% cloudy trichs I start to plain water feed.

Why or why not? In your opinion does it change the flavour, burnability, potency or smoke smoothness? – If I’m honest I don’t think it makes a blind bit of difference to taste, potency, flavour etc etc. for me its a case of saving money on Nutes near the end as any nutes you feed it at this point won’t have any effect on the end product so why bother.”

Hmr81 – GR420 Member

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“I normally flush for the last week.

I’m in hydro and will change the flush water after two days and then run it till done.

Unfortunately I can’t give a comparison as I’ve never just gone straight to chop”

Treetrunk – GR420 Member

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“I think there are two reasons to flush:
– to fix issues
– to make the plant use up its own sugars at the end of the life cycle (ie. shortly before harvest)

I do flush to fix issues if I think there is a salt build-up, or when I screwed up and think I could change EC or pH in the medium by washing out some nutrients.

The days before harvest, I do not flush specifically, but I stop adding nutrients to the water.

I do not think this dramatically changes the plant, but it saves nutrients. I guess it can be argued whether this is flushing or not.

So I guess it comes down to defining flushing!”

Weedabix – GR420 Member

Deep Dive Response From Keeno – GR420 Admin

“There are 3 types of “flush”. I will use all 3 when the occasion calls for it.

Emergency flush.

Mid flower flush.

End of flower flush.

All are suited to salt-based feeds. Growers should avoid flushing any living soils.

The Emergency flush is done when a plant is overfed, there is a ph imbalance in the medium, to refresh the medium, and more. 5 x the volume of the pot in water is “flushed” through the pot/pots when flushing this way. I have and will use this type of flush when needed.

Flushing midway through flower, and flushing before harvest was an unwritten rule amongst the online communities until recent years. I learned from these growers, so have flushed halfway through flower, and then at the end of flowering for many years.

The bro-science reasoning for the flush halfway through flower is as a coco grower using salt-based nutrients/feed, salt residue and deposits build up in the coco over time. A good flush would refresh the coco and “flush” out the salt build-ups.

I will use the mid flower flush when having longer veg periods or using high ratio PK boosts. On basic feed regimes with a shorter veg period, I skip the mid flower flush.

The end of flower flush is used by salt-based growers to in theory have the plant use up stored nutrients. The bro-science reasoning is that the leftover/stored up nutrients within the plants affect the end flavour of bud. This is now a hotly debated topic and I’ve seen growers I personally know not flush their plants and say there is no difference.

I still flush my plants, I was taught this way, but I believe there is another benefit to this. Stressing plants is a good way to make plants produce the stuff we like. For all the attraction of a large bud, it’s not that big beautiful bud that gets the job done.

The resin containing the many cannabinoids and the oils the plants produce are defence mechanisms, the plant will produce more of these defence mechanisms when it believes it’s under attack or stressed. What better way to stress a plant than to starve it at the end of flower.

I will always use the end of flower flush. I will sometimes use the mid flower flush.

In my opinion, it’s more a grower to grower issue. Some growers will be feeding all sorts to their plants. There are boosts for taste, smell, yield. I flush for my own reasons, but if it was a set rule for all I’d say flush should be implemented.

I do believe it affects the flavour, smoothness and burnability if the plants are loaded with all these boosts. Also think if a plant is on a nice simple feed regime, getting just enough food, it will smoke, burn and taste fine without a flush.”

Our Take On The Results

When writing up the initial post about the RX Green Technologies experiment about Cannabis flushing we thought the results may have hit the wider community. On this we were wrong!

Flushing before harvest is more common than not flushing. Most growers go through this process. It is to ensure there are no leftover nutrients or other chemicals in the plant, even if tests have shown no real difference to taste or burnability.

As stated by Keeno this is more down to “bro-science” and a general feel for the need of it by the larger growing community than any actual real life results.

From the information we have gathered it seems that while flushing may help, not overfeeding your plants can be a bigger contributor to quality. Overfeed your plants and you will probably need to flush, feed them just right and it is probably unnecessary.

Let us know what you think in the comments below

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