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Harvesting cannabis is a time-consuming, but straightforward process that involves removing fan leaves from your buds and drying them. And while an indoor cannabis plant will usually be completely clean, i.e. pest- and mold-free, harvesting an outdoor plant can come with some nasty surprises. In this article we discuss washing cannabis buds at harvest to remove all sorts of wildlife you’d rather not be smoking later on.
aphid attack on cannabis plant
This aphid attack looks like a disaster. Before I started washing buds, I would have thrown this one out with the trash!

Common Outdoor Cannabis Pests

Besides police, neighbours and crop-thieves, the cannabis plant has a lot of natural enemies. Indoor cannabis cultivation allows a grower to completely control the environment and prevent anything from entering the grow space. Growing a cannabis plant outdoors however, there’s virtually no chance of getting away without at least some attention from bugs and fungi. Infestations are usually kept in check perfectly by predator insects, but unfortunately these won’t remove every single aphid or mite.

Warmer climates will give you more issues with insects as they don’t get wiped out as harshly in the winter. The same bugs will be present in colder climates, but large-scale infestations are less common. Instead, colder climates will face much more trouble with powdery mildew and botrytis (bud rot).

Most Important Outdoor Pests And Fungi

Of the numerous tiny animals out to get your precious cannabis plant thrips, whitefly, spider mites, gnats and aphids are by far the largest threats. These pests can all be warded off by using natural enemies during the grow, but often you’ll discover a bunch of them, or their eggs, tucked away under a branch while harvesting. Finding pests while harvesting cannabis is never fun, but smoking bugs or throwing out otherwise good buds aren’t very appealing options either. Fortunately it is possible to remove the majority of these bugs quite easily by washing your buds directly after harvest.

Besides bugs, there are two main types of fungal infection that can wipe out your crop even faster. Both botrytis (bud rot) and powdery mildew spread fast and can render your harvest completely unsmokable. Because they both thrive in colder temperatures and especially high humidity, they are also the main reasons we prefer finishing outdoor grows before the fall really sets in. When to harvest buds outdoor therefore depends on the maturity of the plant, but also the current weather and amount of pests. Of course if you know which type of bug or infection you can expect in your region, you can save yourself a lot of hassle by growing the proper strain. Our extensive selection of cold-resistant, mold-resistant strains was bred with these practicalities in mind.
bugs washed out

These bugs came off a few colas. Even if they don’t kill your cannabis plant, you’d probably still rather avoid smoking them.

Unfortunately botrytis can’t be fixed and will leave you in complete damage-control mode, clipping away affected areas and hoping it doesn’t spread. Learn more about preventing mold and bud rot when growing marijuana in our blog article on this subject. Powdery mildew however, can be fixed because it doesn’t grow deeper than the surface of a cannabis plant. Washing off powdery mildew is actually quite easily removed during all cannabis plant stages, we’ll discuss how to remove it at harvest in the following section.

Harvesting Cannabis And Washing

Washing is a great way to remove bugs and powdery mildew from your cannabis plant. Everyone has their own crop harvesting techniques when it comes to washing, but the general workflow is very straightforward: you gently wash your buds with water.

Harvesting cannabis and washing your buds will remove any traces of powdery mildew, the majority of bugs and any nasty webbing that spider mites might have left behind. The number one fear is that washing buds will cause bud rot, but the risk is much smaller than you might think. We do recommend a wet trim before washing in order to minimize water retention after you’re done. Another fear is that you’ll wash off all the trichomes, but you’d be surprised at how sturdy these little guys are. Washing buds will usually reduce the potency slightly, but it still beats throwing away good cannabis! In the following section we’ll talk about how to actually go about harvesting cannabis and washing it.

How To Wash A Cannabis Plant

Let’s assume you’ve just cut down your outdoor cannabis plant and started trimming it. All looks well from a distance, but now that you’re up close you see a bunch of aphid eggs all over a few of the lower buds. Let’s say you also found some powdery mildew, just to make things worse.

Alright, so after the initial disappointment, swearing and being angry at the local climate, we’ll get to washing these buds! We prefer wet trimming and leaving all the buds on their branches because this makes allows you to wash more buds at the same time. In the most common setup you’ll use a set of two or three buckets, we’ll go with the three-bucket approach in the example laid out in the following section. Globally, the workflow will include steps to disinfect and remove bugs, followed by washing off whatever you’re using in the first steps. Washing your buds is about as complicated as doing laundry.
steps to washing your buds

This picture shows the three general steps to washing your buds. By removing mildew and sterilizing your buds, followed by a wash with clean water, your buds will be pest and mildew-free!

Once you have the buckets ready, you simply dunk your buds in the buckets in the right order. The goal is to make sure that water has passed through every nook and cranny in your buds. You can be quite rough with your buds and you’ll probably need to slosh them around a bit for a couple of seconds, especially for dense bud strains. You can also push them under water and leave them in the bucket for about a minute if you prefer not moving every bud/branch around individually. Let your buds drain a bit after each bucket before dunking them into the next one, because they will be dripping wet if you do it right.

Preparing Your Bud Washing Buckets

In the first bucket you’ll wash off powdery mildew, leaving a bunch of nasty residue in your bucket. This will be your dirtiest bucket, so you’ll replace this one the most often. Using alkaline water will be your best bet to clean the buds as powdery mildew does not like an alkaline pH range. A sudden shift in pH will also shock the bugs on your cannabis plant, which will hopefully cause them to fall off in this first bucket.

powdery mill washed out

The gunk in this water is powdery mildew, you’d be surprised how easily the spores come off your cannabis plant with a little wash

If your tap water has a pH of >8 you’ll usually be fine using only tap water, otherwise add in about 1-2 grams of baking soda per liter of water. We prefer using baking soda over other options as it is cheap and non-toxic. The second bucket will be your disinfecting bucket and will generally contain a low concentration of hydrogen peroxide and/or lemon juice. This is the “dangerous part”, because using too much of these substances can certainly cause damage to the trichomes. We generally squeeze out half a lemon in about 10 liters of water, which will give you a solution that contains around 1% lemon juice. We prefer keeping additions to your wash-water as low as possible, but we have seen plenty of proper washes with up to 5% lemon juice in the washing solution.
pre squeezed lemon

Avoid pre-squeezed lemon juice, bottles like this often contain oils that can absorb some of your cannabinoids.

The other addition to the second bucket will be hydrogen peroxide, or H2O2. This natural antiseptic is often used to bleach hair or sterilize cuts in the skin. It can be dangerous to use at higher concentrations, so make sure you dilute this properly. Generally you’ll find hydrogen peroxide in stores at concentrations of 3-12%, but our working solution will be closer to 0.03%. If you’re using a 3% peroxide solution, this would mean using 10 mL of peroxide per liter of water. If you’ve bought a stronger solution, you’ll simply have to dilute it more.
step 2 of washing your cannabis buds

This bud is in the middle of step two and is almost ready for drying!

After these two steps your buds will be free of bugs and mildew, but will have peroxide, lemon juice and possibly still some baking soda on them. Now it’s time for the third bucket, which will only contain room temperature tap water. In this final washing, you use clean water to wash off any residues of the substances from the previous steps. After your washing cycle is complete, this should be your cleanest bucket.

Washing Workflow Variations

The washing workflow we outlined in the previous paragraph is a global, universal type of workflow, but washing is one of those things every grower does differently. Depending on the strain of cannabis plant, time of year, soil quality etc. you might want to modify your washing regime. One of the most common variations is to use the same bucket for the first two steps outlined in the last section. Taking this route would mean using one bucket with baking soda, lemon juice and hydrogen peroxide for the first round of washing. Because the first bucket always gets dirty quickly it will usually need to be replaced several times, making this a less resource-efficient approach than using two separate buckets. If you are 100% sure your cannabis plant does not have any powdery mildew however, you can even skip the baking soda bucket.

A lot of growers also prefer leaving out the hydrogen peroxide, as it is does not sound very biological. Despite the fact that the human body produces hydrogen peroxide itself, a scary chemical name can make substances like this feel quite dangerous. We prefer using hydrogen peroxide to be sure our wash is successful, but washing without hydrogen peroxide is also a perfectly viable option. Lemon juice essentially fills the same antimicrobial role as hydrogen peroxide, but we like to add in as much certainty as we can.

Another popular modification to this workflow is adding more washing steps after the baking soda, lemon juice and hydrogen peroxide. While a single wash will generally take care of the already low concentrations on your cannabis plant, adding a second or even third washing step can be a good way to ensure a super clean smoke. We prefer leaving it at one final washing step to prevent more trichome damage, as we’re using low concentrations anyway. You can also perform the final wash in the sink by carefully washing your buds under a room temperature tap. This might be a bit rougher on your buds and might cost you a bit of trichomes, but it does make washing a lot quicker and easier.

simply was your buds in the sink

For the “quick and dirty” approach, simply wash your buds in the sink under a room temperature tap.

Other bud washing variations include buckets with hot or cold water, but we’d rather stick to room temperature. If you’ve ever made bubble hash you know that cold water is great at beating the trichomes off of a cannabis plant, and that certainly isn’t the goal here. Warmer water won’t necessarily damage the trichomes, but can still weaken the structure of a cannabis plant enough to have an effect on the final potency.

Drying Washed Cannabis Buds

After washing your freshly harvested cannabis buds, you’ll have some soaking wet flowers on your hands. If this is your first time washing buds this is probably the point where you start to think you’ve wasted your entire harvest. But don’t be alarmed, it might take a few extra days to dry, but your buds will be fine.

drying your buds on a drying rack

Blowing a fan under these buds for an hour or two will get rid of the big droplets of water. After those are gone you can dry your buds as you normally would.

Most growers that wash their harvest will “quick-dry” their freshly washed buds until the biggest drops of water are gone and go back to normal drying after that. What this generally means is that you’ll add in some air movement for an hour or two after washing. We usually hang the washed buds or drying rack with washed buds near (not in front of!) a fan until they’re as wet as they were before the wash. In general, washed buds will take a few days longer to dry than unwashed buds.

Final Thoughts On Washing Cannabis Buds

We hope this article has given you an idea on how and why you should wash your cannabis buds. By breaking down the different steps involved in washing buds, you should now be able to figure out which buds are salvageable and how you can develop your own unique method

cannabis bud with bud rot

Be thorough though, or you might be unpleasantly surprised!

A lot of cannabis enthusiasts will argue that washing cannabis buds has many advantages. They say that if we wash every vegetable we eat, washing every bud we smoke makes perfect sense. A clear argument for washing buds aside from removing pests, is that it allows you to foliar feed during flowering without the risk of consuming leftover nutrients. Many are also convinced that washed buds make for a much smoother, cleaner smoke. Whether these arguments are completely true or not, they do make a lot of sense.

Because harvesting cannabis is already very time consuming however, most growers will avoid washing buds as much as possible. The risk of breaking off trichomes is also always present, so washing buds can potentially diminish the potency of your harvest. We prefer to look at washing cannabis buds as an extremely effective way to save a crop after finding pests or mildew near the harvest date. Whatever you do, wash or no wash, we wish you the best of luck with your next grow, and hope your cannabis plantwon’t have any of the problems mentioned in this article at all!