How To Properly Ripen and Flush Cannabis Prior to Harvest

Cannabis takes months to mature and flower, with numerous hours and many cash poured into your funding. Skipping out on a correct ripening section means ruining your complete crop, and flushing money and time down the drain.

Flushing is way more than simply releasing the construct up of salts in your rising medium or hydroponics system on the finish of the rising cycle. If executed correctly your flowers is not going to solely be utterly cleaned out of any vitamins used throughout the development, but additionally ripened to their full potential. Properly ripened flowers will exhibit a way more profound aroma, look, and style whereas the THC and different cannabinoids may have a greater, extra usable impact on the physique. Most significantly, it would burn correctly, and you’ll solely be smoking the hashish, not the vitamins.

In case you run a medical growroom (ACMPR), micro-cultivation facility, or licensed producer you owe it to your self and your clients to implement correct ripening methods so your product is clear and passes lab inspections

When To Begin a Flush & for How Lengthy

grower examining pistils
If you understand that the pressure(s) you’re working with takes eight weeks to complete from the beginning of flower then it’s simple: you simply begin your flushing section at week six of the flowering cycle.

In case you don’t know when the cultivar you’re working with will end flowering, then its greatest to make use of the red-hair approach.

The Pink-Hair Approach

The stigma (or pistils) is the hair-like a part of the hashish flower. It grows out from the calyx and its foremost function is to gather pollen from the male plant when launched. The calyxes are designed to guard the crops reproductive system, nevertheless, for many growers (aside from breeders), you received’t want to guard any seeds.

Your stigmas shall be white or delicate yellow to start out and over time they’ll flip a shade of pink relying on pressure. With the red-hair approach we’ll simply look ahead to the pistil colour growth on the flowers and begin the flushing section when we’ve between 50-70 p.c general colour growth on the pistils of the plant. This may make sure that over the subsequent two weeks of flushing, your completed crops shall be within the 75-90 p.c red-hair vary.

The explanation behind it is because we don’t need to let the crops proceed to develop at one hundred pc pistil colorization because the THC can start to keel over and die throughout this time. The perfect window for harvesting is between 75-90 p.c pink hairs with 75 p.c being extra geared in direction of the milky trichome preferences and the 90 p.c space extra for the amber trichome and pronounced terpene profiles.


  1. Learn your crops’ hairs (pistils), not the calendars.
  2. Provoke the flushing section when 50-70 p.c of the pistils have turned orange or pink.
  3. Flush for 14 days no matter rising model, vitamins, or pressure.

The Flushing Part

grower inspecting pistils with a loupe

Flushing shouldn’t be neglected. It’s such a vital a part of the rising section the place it inhibits bulking and ripening of the flowers whereas packing on THC when executed correctly. Initiating a flush for 14-28 days when your plant is on the 60-75 p.c mark is the overall rule, relying on the pressure. This may ripen your flowers totally, giving probably the most sturdy flavors and highest THC your pressure is able to whereas packing on weight and cleansing the flowers out of saved vitamins (yuk!).

Once you cease feeding the plant, the roots now not must assimilate the vitamins which permits them to concentrate on the terpene manufacturing and flower density. Throughout a correct flush your flowers will swell and harden, and the whole crop ought to begin falling over if its above three toes, hopefully on to their trellis or helps! Your crops will even start to cannibalize themselves by consuming up saved vitamins of their leaves — that is what provides these lovely fall colours of purple, yellow, and orange.

Fourteen days is normally sufficient for many strains, it’s only the sativa-dominant strains that typically want longer. Watching your hairs or stigmas is one of the simplest ways to know when to reap. This technique is extra exact than following the really helpful rising size in your seed by way of the breeder. Each phenotype is totally different and the seed info shall be generic or primarily based on common timelines, whereas each seed will tackle totally different traits, typically extra of the mother, typically extra of the dad.

Best Flushing Situations and Surroundings

cannabis plants in a growroom
Plain, non-pH adjusted water is a given however what else is concerned in an excellent flushing section?

The growroom design and setting are crucial to your success, and controlling it correctly shall be key to producing craft-quality bud.

It would be best to minimize carbon dioxide (CO2) off utterly throughout the ultimate two weeks of flower to permit your buds to harden correctly and develop probably the most aromas and THC attainable.

Cooler temperatures are additionally really helpful. We need to ease the temperature down step by step like with any transition in rising. The primary week of flush ought to be dropped down 2-4°F (6-8°C) out of your regular temperature and the ultimate week ought to be a further five-degree drop, typically much more in case you are attempting to drag out the anthocyanins within the hashish that trigger the purple colours.

As quickly as you see that your stigmas are at that 60-75 p.c mark, decrease your gentle depth all the way down to 60 p.c your first week of flush after which to 40 p.c in your ultimate week. This mimics the solar being farther from the crops on the finish of summer time due to the Earth’s axis and permits your buds to harden up correctly, changing into a lot denser. Go the additional mile by turning off each second gentle to assist create density within the flowers and keep cooler temperatures.

Really useful:
How to Plan Forward for Your Cannabis Harvest
Figuring out and Stopping Mould in Harvested Buds
Suggestions for Dealing with Contemporary Cannabis at Harvest Time

Flushing Quantities

The flushing section shouldn’t be the identical as your regular water feeds. It would be best to feed the crops greater than regular with water that’s as clear as attainable, with zero vitamins and no pH up or down.

Feed your crops two to 3 instances the quantity of water as regular—reverse osmosis water is good on this stage in addition to development if you happen to can. Don’t let your run-off water sit in your trays or tables. If utilizing recirculating hydroponics, flush out your system way more continuously than regular. This may permit the expelled vitamins constructed up in your root base or medium to clean off. In fact, recirculating hydroponics runoff will attain low PPM faster than a system with a develop medium, however it’s nonetheless simply as essential to flush for the 14–28-day interval to permit the plant to undergo the ripening course of, cannibalizing its leaves, utilizing up saved vitamins, and packing on the THC and weight.

No Must Regulate pH in Flush

hydroponic cannabis plants
It isn’t crucial to regulate your pH when flushing, as the one motive to regulate pH is so your plant takes in the correct degree of vitamins.

The adjustment of alkalinity and acidity within the water from pH up and down provides phosphoric acid, potassium hydroxide, and potassium carbonate when utilizing horticultural pH adjusters. That is executed as a result of we want the nutrient answer to replicate the right pH vary for our crops, which in hydroponics for hashish is 5.5–5.8, so if there are not any vitamins within the water, there isn’t a want to regulate the pH. Plus, we need to clear the crops out, not add extra issues.


  1. Flush with non pH-adjusted reverse osmosis or clear water for at least 14 days.
  2. Watch your pistils’ colour growth.
  3. Feed two to 3 instances the common quantity of water in a drain-to-waste system, and flush out two to 3 instances as a lot in a recirculating hydroponic system throughout flush.
  4. Don’t let crops sit within the runoff; permit correct drainage.
  5. Reduce off CO2 enrichment utterly when initiating the flushing section.
  6. Decrease gentle depth to 50 p.c when initiating flush or flip half your lighting off if you can’t decrease depth.
  7. Decrease temperatures within the room by 2-4°F (6-8°C) the primary week of flush.

Superior Ripening Strategies

Superior ripening methods will convey out the anthocyanins in your hashish. These are the pigments or flavonoids that trigger the purple colour, altering the colours of your pistils from an orange to a deep pink or pink. These methods can massively enhance your THC content material or assist sugar up the within of a cover that didn’t obtain good gentle.

Chilly Water or Ice Therapy

ice cubes on top of soil

This technique refers to chilling the develop medium of the crops by both chilling the water of the recirculating hydroponics system, or the feed water to your crops in soil, coconut husk, or stonewool. You are able to do this by buying the big blocks of ice from fuel stations typically used for fishing and inserting them in your reservoir tank, whereas setting your water chillers to the bottom setting or including ice above the crops.

Utilizing this technique (together with cooling the room) will convey out a number of colours within the hashish, in addition to THC. THC and different cannabinoids are a protection mechanism for the plant to guard itself from pests (they persist with it). We prefer it for different causes, although! Including extra stress like this in direction of the top of the crops’ life will naturally convey out extra of what we love.


  1. Cool the water of your feed tanks to as cool as attainable to convey out colours within the hashish (anthocyanins)
  2. Use giant blocks of ice and water chillers to lengthen their cooling interval


cannabis plant in darkness
In the course of the ultimate 48 hours of the plant’s life, you may implement what we name “Armageddon” to induce an enormous ultimate push of cannabinoids and colours to the plant by way of gentle and temperature stress. Throughout this final 48 hours, it would be best to preserve the rooms utterly darkish and as chilly as attainable. This could solely be executed for 48 hours as extra time may cause seeds to start growing. Now we have examined this 48-hour technique on numerous strains and might guarantee your crops shall be simply superb.

This method might be nice for sugaring up the within of a cover by harvesting all the highest flowers, then leaving the within cover for 2 days earlier than you chop it.


  1. Solely implement “Armageddon” for the final 48 hours earlier than harvesting
  2. Make rooms as darkish and chilly as attainable
  3. Be light when harvesting chilly hashish because the trichomes are extra brittle at this stage

The Finest Time to Harvest After Flushing

macro image of cannabis pistils and trichomes
When it’s nearly time to reap, you may look slightly deeper into issues and look immediately on the trichomes of the plant with a 5x microscope, a loupe, or a great telephone digital camera. The trichomes are small factories, creating totally different cannabinoids and terpenes, amongst different issues. The top of the trichome shall be a transparent ball most of its life, although towards the top it would undergo a milky white stage, then amber, and at last a darker shade of pink because it begins keeling over and dying (we don’t need that!).

I personally desire to reap my hashish when the trichome is a milky white with some beginning to flip amber. It is going to be at excessive efficiency at this level with no dying trichomes, with out an excessive amount of of the sofa lock that comes with the amber trichomes (and indica strains).


  1. Use a microscope, loupe, or good digital camera to see your trichome growth
  2. Don’t let the trichomes keel over and die (this might be rising previous one hundred pc pink hair)

In case you have ever tried to smoke hashish that didn’t burn or did burn however the ash was peppered or darkish, there’s a good likelihood that you just had product that the grower skipped a correct flush on. Flushed product working strategies like these will come out burning clean with gentle gray or white ash. Flushing shouldn’t be solely crucial throughout and on the finish of manufacturing however is an integral a part of rising craft hashish.

These ripening methods and all of the strategies provided listed here are the outcomes of greater than 23 years within the subject. Comply with these strategies and also you’ll develop the best-quality craft hashish attainable.