We generally recommend keeping things simple.
At least on your first grow or two.
After that, go ahead and start experimenting with some of the millions of tips you find online.
One of the most common tips is to withhold water in the last few days before harvest.
Unlike many, this trick does have a positive effect.
The big question is: when to stop watering before harvest. The advice you see varies greatly.
There is a reason for this. We’ll get into that and everything else you need to know about withholding water prior to harvest.
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When To Stop Watering Before Harvest
To get the best yield, some growers say you should stop watering your plants about 3 days before you plan to start harvesting the buds. Others swear they stop a week before harvest.
The idea is to withhold water so the plants have a stress reaction like they do when a drought may be coming. They divert all their resources to reproduction, which results in bigger fatter buds.
How long before harvest is ultimately up to you and may be unique to your situation. The ideal amount of time differs from one plant to the next. Overall, 3 days to a week seems to be the accepted wisdom.
Why Does Withholding Water Before Harvest Work?
There is a natural response in cannabis and many other flowering plants, where the plant will divert all its resources to the flower when it senses stress coming.
This is a form of plant parenting, and it is hard coded into their genetic code. When cannabis is stressed, and already in the reproduction phase (flowering), it will put all its effort into saving the buds.
Withholding water for a period before harvest is a severe form of stress to put on a plant that is used to getting watered regularly, and it produces a severe response.
Growers all agree that this tactic of stressing the plants by holding back the water makes a big difference in the size and density of the final bud harvest.
Depending on your strain of plants, you may need to adjust the drought period from between 3 days to a week. Each strain is a little different and has different requirements, but a week is a safe bet for all of them.
Other Water Changes To Make Before Harvest
There is a process called flushing which will also help increase the quality (not necessarily the quantity) of your yield. The idea is to give your plants only clean water with no additives for a period before harvesting, which cleanses the buds of the minerals and nutrients the plant needs to grow.
Harvesting without flushing will produce buds that contain the minerals and nutrients you were adding to the water.
When burned, this produces smoke that is too dense, because it is filled with other burned compounds besides the buds and the trichomes and THC.
In the wild, it is natural for the nutrients in the soil and water to end up on the flowers of the plants. This causes no problems for anyone or anything in nature. In fact certain plants benefit from this by making the flowers more fragrant and brighter colored, which attracts pollinators.
The issue with cannabis is that we are growing it to smoke it. And we don’t want to smoke any additional compounds.
The soil nutrients and minerals that naturally make their way to the buds cause coughing, bad taste, and on overall unpleasant smoking experience. This is nasty and can ruin your entire crop. Flushing is the answer to stop this problem, but many people are doing it incorrectly.
How To Properly Flush Your Cannabis Plants
Follow these guidelines to ensure you flush your plants correctly and get the best possible tasting buds. We also have an entire article on how to flush marijuana plants.
Get the timing right
The best time to flush your plants is about two weeks before you plan to harvest your crop.
If you use a portable microscope to look at the trichomes (the little resin balls on the buds) you can tell if it is time to start the process of flushing.
Normally the trichomes are clear. If you notice them starting to appear a bit milky or cloudy, that is your clue that it is time to start the flushing process.
Now start the flushing
This is as simple as it sounds. At the time of day that you would normally feed your plants, flush them instead.
Use normal water (i.e. do not add any nutrients) and fill the pot with as much as it will hold. Wait and let the dirty, nutrient filled water drain away from the plant’s roots. Once the soil is no longer saturated, repeat the process again and let the water drain out completely.
Measure the results
You should consider measuring the amount of solid minerals and other materials that are coming out of the bottom of the pot in the drained out water. This will give you a clear indication that you are getting the job done.
You can pick up a total dissolved solids meter (TDS meter) which will give you a numeric value. Ideally you want to flush until the total number is less that 50 to 70 ppm.
The caveat here is that all tap water has some solids in it, and if you measure the tap water before you start, it may already have a ppm over 70.
The number you get from the drain water should match the number you get from the raw tap water, indicating that there are no extra solids coming from the plants soil. If your tap water has a lot of dissolved solids, you might want to consider filtering it first, or using a different water source.
Other Watering Tips
New growers often over-water their plants. This is done with the best of intentions, but the results can be catastrophic for the plant. It can cause root rot and other issues.
A proper cycle of the roots being wet, and then dry for a period, is necessary to maintain a healthy plant. There is a reason cannabis does not grow well in boggy marshes. The roots need to dry out periodically.
Underwatering is also a huge problem. You can tell your plants are underwatered if they appear saggy and limp. They look sad, and if plants had emotions that is what an underwatered plant would be feeling.
How Often Should You Water Your Plants?
First off, there factors to consider because not every environment is the same. Consider the temperature outside, the stage your plants are in, and how big they are.
The general rule of thumb is to get your plants on a 2 to 3 day watering cycle. If you live in a very dry area, the soil will dry out faster than in a humid zone. Keep an eye on your plants and know your environment. If you can get them on a 3 day watering cycle you are doing it right.
When To Stop Watering Before Harvest: Final Thoughts
The reason you see such varied answers regarding when to stop watering your weed plants before harvest is that the ideal time differs, depending on the strain and a few other factors.
That’s why we recommend keeping it somewhere in the rang of 3 days to 1 week for your first grow, and then adjusting from there. It will take you a few grows to get it perfect.
Of course, this assumes you are growing the same genetics each time. Either way, if you keep it in this range, you may not hit the exact perfect spot, but you will still see a marked increase in yield quality and quantity. So you really can’t go wrong.
Stephan says
Hi everyone im new in indoor growing and sits with a big problem. I have 4 plants under a 400w led light. 2 of the plant have only some leaves thats clawing down. So much that its making sirkels. Im in 3 week of flowering. I know its not over watering or over feeding as a confirmed that. I do not gave any yellow leaves. Everything looks healthy except from the clawing. Can that be bad soil or root damage? As my soil is not right. (To hard) is there a way to fix this problem now in this time of the growing process??
John Gross says
Sound ike dirt grow., this can be caused by over watering or 2 intense lighting.
I would test soil ph and adjust it, but being flowering maybe adjusy soil ph but doing a 6.5 ph water flush,
But most likly cause over watering . If its dirt , its 1 every 3 days., water intel a littlr comes out bottom.
If you water every day id start by chaning to every 3.
If u water every 3 days. Then id flush it.
And if your really worried about it, repot it, as it move it to anther conatiner with fresh dirt.
With 400w light u need to be like 2 feet away with a fan
If its to close can do that also, as a way of getting out of sun,, google leaf curling.
Peace n blessing apon u.
Anonymous says
I think it’s a underwatering problem
Thomas Scott says
You some had one LED UFO 900w grow light and one LED UFO 600w grow light how far would you think it should be far from your MMJ plants? I’m thinking about 3ft?? Thanks
Dan says
Quick help last week and half of flowering I found spider mites!! Can’t really treat was going to just ride it out cut harvest a few days short?? Any thoughts?
What do I do once I do harvest to remove mites before drying/curing??
Buds look fine noticed a little web on one site but a lot of eggs on fan leaves should I just cut the fan leaves Infested and save the rest about 50/50 fan leaf reduction ? How would this affect harvest/ bud growth?
Any help or comments I would greatly appreciate it.
Tommy says
Idk Neither bu5 would atleast I will go get a vacuum cleaner And suck them up lol
Misty Hill says
Vacuuming them is probably the ONLY thing u could do at this point if so close to harvesting….I recommend hanging them upside down in a dark cooler area, for the mites hate that!! As the plant starts to dry they can’t feed and will scurry off your plant and March like ants in single file to search around for light and new plants!! Ur not selling to a dispensary, so u don’t have to worry about getting EVERY single mite, I think we have ALL smoked a mite or 2 in our days…. ALWAYS SEARCH FOR MITES THO, waaaay before harvest for they are terrible for the growth and potential of your plant, the webs suffocate the buds eventually sucking out ALL nutrients from bud and turning them brown to the point it looks not smoke able, which they arent… I found using 2 different mite killer sprays because they quickly immune to 1, so the 2nd throws em’ off tremendously!! Just a little personal experience I’ve endured and thought I’d share what worked for me!! Thank u!!
Anonymous says
Buy ladybugs..release them in your room during the dark cycle…1-2 weeks ladybugs gone eat everything soft bodied ..if u can go a extra day or two use lady bugs 2weeks no mites
David says
Wash your buds. It’s quick and easy. You need to do it correctly however. Go on YouTube and search “marijuana bud washing”. Many people do it all the time to get cleaner tasting and more colorful buds.
Anonymous says
Cold water kills thim put ice water in spray on thim it works
Anonymous says
Use a vacuum with gauze over the opening so you don’t suck any of the plant in as well. Don’t spray them AT ALL. Don’t use any liquid on them at this point or you can also get bud rot and molds.
Anonymous says
I use seven dust to kill mites and other insects. Pour a small hand full and put a a fan facing up, put your hand with the seven dust in front of the fan this will create a nice small dust cloud that will spread the dust lightly on the plants. Within 24 hours you mites and other insects will be dead.
mark says
sevin garden dust is toxic not rcommended!
Anonymous says
In regards to flushing and stopping watering before harvest. Would it be best to Flush until the PPMs are low enough, stop watering for a week and then harvest?
madethescene says
Yes, but base the time on tricomb color according to the type of effect you want. Cloudy% Amber%
Many people have the idea of flushing completely wrong. The internet does not put any mark next a posters name indicating how and IF they know what they are talking about,…so who’s to believe.
After I see what I want to see with the tricombs…I water them completely with 74-78 degree water ph’d at 6.2 or close,(so most nute salts will dissolve), preferably with a flushing agent like Final flush or the like, water until 20% runoff or so and stop…let sit for 15 min to 30 min.
Then, flush with ph’d 74-78 degree water with 20% runoff to “flush” the salt built up the 15-30 wait achieved. You only need to worry about PPM if you used heavy nutrients that built up concentrated salts in the root system. Only need multiple flushes if the same is true.
You want to use whatever process to dissolve the salt buildup- if any. It’s debatable if flushing is even necessary as some would suggest that yellowed starved leaves in the last week is more important indicating the plant is feeding on itself and there are no longer any nutrients left in the soil needed to flush in the first place. Some say staving a plant in the last couple of weeks is wrong too.
I do it anyway…can’t hurt and clean almost pure looking runoff after a week of plain water is self evident.
I never check PPM… if I was large scale I would.
Jan Kokes says
Thank you. I thought dry environment helped with strength. I came to verify. I let them dry out until dead, fully dried and most perfectly cured, all while keeping them legal (unlike harvesting a whole plant at once).
I don’t flush the nutes to no ill effect I can tell. Perhaps because I use all natural solution exclusively. I make it myself using my urinary tract and the process of fermentation.
Bill says
Hello fellow growers I hope you are having as much fun as I am. I am finding out that these are some of the most amazing living “friends” that I have ever met. This is our 2nd year of outdoor growing and it’s been a learning experience, I have the utmost respect for our ladies. We have grown godbud the last 2 years and it was the indica side last year with our 3 plants and were able to harvest 10.5 lbs of usable flower. This year 2 are sativa phenols and the indica clone from last years giganto 7.5’ tall and 38’ send! Sativa seem to be a lot more temperamental than the indica so we will see. We are about a month away and things are looking up ha about 14’ up sorry my dog says I need to go so have a great day everyone and listen to everyone’s advice and choose what works for your situation.
Bill says
Hello from Oregon we are in year 2 of our learning process and I would advise people to listen to what others have to say and take something from every conversation whether you use it or not because it might apply to another grow later. These are some of the most forgiving plants so don’t give up on them if they get sick just be very patient and treat them like a lady and they will reward you. One of my mistakes this year was poor soil prep on my part, that’s what gets it all going and I slacked and paid for it but like I said don’t give up and above all don’t think you know it all and take advice.
Scott says
Live ladybugs are a cheap solution to spider mites. No neem or any other pesticide necessary. I used them in my indoor tent. They like to stay in tent even if door wide open. The few that get out are easy and not gross to get back in tent. They are fascinating workers. I get mine off Amazon from a place in LA called THC The Hydroponic City is in the company name. You can get 1500 for about $15 shipped. I have tried ladybugs from other companies, but not as good as la company. I sprinkle about 15 or 20 on a plant. A few may be dead, you can vacuum up later. They don’t bite. Make your grow more interesting to watch.
Jesus Sanchez says
Is hydrophobic soil with the wetting agent ok to flush out before the harvest
Dr.B says
Flushing doesn’t help flavor and doesn’t do much else