For as long as I can remember since using and working with Cannabis the question has always been asked, does flushing really matter?

It’s a debate which divides the community. Some think flushing is everything to a good crop while others believe it truly makes no difference – As long as you do a good job with everything else.

Today we will take a look at some interesting research done on the flush or no flush debate.

Why are we questioning Flushing today?

A trial posted results that flushing 2 weeks before harvest makes no difference to the taste or quality of cannabis flower. The results show that blind testing couldn’t find much of a difference between flushed and unflushed plants.

While this is common practice amongst cannabis growers and something that is always spoken about these tests throw a spanner in the works. It is believed that the flush is essential to getting the best taste as well and burnability from your plants. As well as getting rid of any unwanted chemicals by nutrients & other substances that help the grow cycle.

Flushing is in fact so popular that Danny Danko (High Times senior cultivation editor) had this to say about it:

“Flushing is important because it removes excess nutrients that are leftover within the plant, So it helps with the burnability of the flower by leeching out excess salts and nutrients.”

This is the belief amongst most cannabis growers and has been for as long as I can remember. I am sure you have had some bud at a time which didn’t burn well or felt rock hard and someone would have put that down to not flushing.

What was the study?

RX Green Technologies – a manufacturer of nutrients and other cannabis products, took 4 groups of 12 Cherry Diesel plants from the same variety with different flush times.

All plants were grown in a coco based medium with each group having a different flush time when approaching harvest. The time frame for the 4 different flushes were 0 days, 7 days, 10 days and finally 14 days.

Samples were taken from the flower a day before harvest to test plant nutrients. Plants were then harvested then cured with further testing being done on overall flower weight, terpenes and THC percentages.

Once the tests had finished, taste and smoke tests were done on a blind tasting basis to keep things fair.

What exactly did the study show?

The results of the trial may surprise some of you. Those who blind tested actually seemed to prefer the flower which had not been flushed prior to harvest. This throws a big curve ball to all the theories which have been in the cannabis growing world for many years.

Other tests found no significant difference between in yield, THC potency and terpene content from each flush time period. There was also no real difference found in the tests for the mineral count in each of the groups of flower.

Further data from the blind tests showed that taste from the non-flushed plants were preferred. Smoothness of smoke, colour of ash and overall flavour were also not affected by the duration of the flushing period.

What did the experts at RX Green Technologies have to say about the tests?

When reflecting on the tests RX Green Technologies director of research and development Stephanie Wedryk Ph.D. said:

“I did not know what to expect going into this. I had talked to some growers I know and all of them had experience with testing flush times and not flushing and all of them only had negative experiences when they did not flush.”

While Stephanie Wedryk isn’t saying growers with their proven methods should up and change them based on this test, she believes they should be open to giving something like this a try and see how it works. More testing in more environments is always a good thing when looking into anything like this. “I would definitely recommend that growers play around and find what works best for them. I talked to a grower at the event who doesn’t flush and he’s perfectly happy with his product. Everybody has their own unique system and there are so many different components that go into growing. What works for one grower because of their unique set of circumstances might not work for the other grower.”

Could there be a bigger reason at hand for some to feel the need to flush every crop?

Danny Danko said this about nutrient companies often advising growers to use too much of their product in the process:

“Really, flushing is an extension of the fact that most people are over-feeding their plants. Advising growers to feed their plants lightly, in many cases at lower levels than recommended by nutrient manufacturers. It’s always easier to bump up the nutrients when you see a deficiency than it is to remove nutrients when you’ve overfed”

Danko would still recommend people to flush their plants prior to harvest. However the research in this trial is a good point for all of us to keep an open mind. Not everything we think we know or have heard is always correct. We need to challenge these beliefs sometimes in order to grow further.

With more testing being done on Cannabis today than ever we are sure there are going to be plenty of topics like this that divide the community regardless of the results in tests.

At the end of the day everyone has their own preference and ways of making things work. To each their own as they say.

What do you think about flushing? Let us know in the comments below whether you flush or not and what difference it makes to your crops.

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