When it comes to flushing cannabis – timing is crucial! By flushing your cannabis plants before harvest you can avoid a harsh and unsatisfying end-product.
If cannabis plants are not properly flushed, the minerals and nutrients used during the cultivation process are still present. Flushing removes all nutrients and improves the overall quality of your bud. Flushing cannabis is easy! Here’s how:
How to Flush Cannabis
1. Test the pH level of the water (tap is acceptable) to ensure it’s in the appropriate range for cannabis plants (between 6.0 and 6.8 for soil grown).
2. Water the plants at the time you would normally feed them without giving them any nutrients or supplements. Don’t water your plants more than usual to prevent deficiencies.
3. Repeat 15 minutes later.
4. To make sure the flush was successful, use a TDS reader to measure the total dissolved solids and find out how pure the water runoff is.
It’s ideal that the water draining out of the pots is as close as possible to the TDS (total dissolved solids) reading of the neutral water you’re flushing with.
5. Keep an eye out for signs of too much yellowing. The pre-harvest flush may cause a plant to lose its color quickly. It’s normal to see some yellowing, but it’s critical to harvest before the leaves on the buds have yellowed.
Once all the leaves have turned yellow your plant is at the end of maturity and buds will start to deteriorate.
6. After flushing, your plants will be a lot lighter in color and are ready to be harvested.
Flushing cannabis is used to remove buildup from the roots and soil of a plant not. It’s been recommended to flush at the beginning or the end of a day when plants can be misted (this lowers their transpiration so that they do not over hydrate).
When to Flush Cannabis
Finding the best time to start flushing will vary based on how close your plants are to harvest and the knowledge and methods used by the grower.
Generally, flushing cannabis normally takes place two weeks before it is harvested. If the plant has an 8-week flowering period, flushing should start 6-weeks after the beginning of the flowering stage when trichomes begin to form a cloudy white color.
Flushing cannabis removes leftover nutrient buildup from the roots and soil of your plants giving them a fresh start. Flushing effectively allows your plants to absorb any nutrients that are still in the soil.
Flushing cannabis too early and too often will restrict nutrients and restrain the plants from growing and flowering. Flushing too early can also result in yellowing or discolored leaves.
Flushing Cannabis – The 3 Times You Should
1. Pre-harvest flush
2. Sudden change in the nutrient cycle
3. Nutrient Lockout
1. Pre-harvest flush – Flushing is used during this stage to improve the quality and smoothness of cannabis. A flush during pre-harvest will force plants to use up the nutrients stored within themselves while preventing harshness and removing excess chlorophyll.
If the nutrient reserves are not used or broken down they will negatively affect the quality of cannabis buds. This should be done between a week and 10 days before harvest and repeated three days later.
2. Changes in the nutrient cycle – Cannabis has different nutrient requirements depending on what growth stage it’s in. Cleansing cannabis of old nutrients is a good way to reset soil while a plant is transitioning into a new stage of growth.
Think of this as a preventative flush. It’s not required, but by the time a plant reaches the flowering stage, it has sucked all the nutrients from the soil and could benefit from a fresh start.
Flushing Cannabis – The 3 Times You Should
1. Pre-harvest flush
2. Sudden change in the nutrient cycle
3. Nutrient Lockout
1. Pre-harvest flush – Flushing is used during this stage to improve the quality and smoothness of cannabis. A flush during pre-harvest will force plants to use up the nutrients stored within themselves while preventing harshness and removing excess chlorophyll.
If the nutrient reserves are not used or broken down they will negatively affect the quality of cannabis buds. This should be done between a week and 10 days before harvest and repeated three days later.
2. Changes in the nutrient cycle – Cannabis has different nutrient requirements depending on what growth stage it’s in. Cleansing cannabis of old nutrients is a good way to reset soil while a plant is transitioning into a new stage of growth.
Think of this as a preventative flush. It’s not required, but by the time a plant reaches the flowering stage, it has sucked all the nutrients from the soil and could benefit from a fresh start.
3. Nutrient Lockout – Growers that understand how to balance nutrients individually don’t have to worry about flushing as much as those who rely on pre-balanced nutes.
Using pre-balanced nutrients may offer immediate results, however, after the first few doses, your plant is likely getting too much of one nutrient and not enough of the others creating a deficiency. A deficiency in plants is not always due to a lack of nutrients but can be because a plant has too much of a nutrient causing its system to become unbalanced.
By overfeeding a plant’s nutrients, it will absorb what is needed while the access sits in the soil. This leads to a build-up of unnecessary nutrients which is known as Nutrient Lockout.
Generally, when dealing with a serious nute imbalance, the cure is to flush the plants and add a fresh, well-balanced, mild dose of nutrients. It’s important to pay attention to the details; don’t just flush cannabis because of minimal changes.
If you notice a drastic change in your plants but there are no other issues (heat, root rot, etc.), flushing may be a good idea to remove excess build-up and help restore the soils pH balance.
This is all a personal preference I believe. I just harvested my first grow. 2 weeks prior I flushed 2x the size of my pot. then until harvest just used plain water to feed. The smoke is super harsh and I think its due to not enough flushing. I was using Fox Farms GB BB and TB. After smoking it for a while I am used to the harshness and it does not affect me. this could be why people who do not ever flush dont ever have harsh smoke: because their used to it. but when I try some different smoke for a while and come back to this, i see how harsh it is again. I will definitely do a more precise flush with my next grow.