Cannabis pollen collection and storage can be a little bit tricky for the new grower, but the benefits of starting your own pollen collection can be well worth the trouble. An endless supply of cannabis seed awaits those with a little patience and an extra grow tent to segregate the male plants.
Once you have identified the male and female plants in your cannabis garden (see my tutorial here) you’ll want to remove the males from the proximity of the females as soon as possible. While generally speaking the males will begin releasing pollen well before the females are ready to receive it and become fertilized, occasionally an early flowering female can get a head start on the blooming process. This makes it important to keep a close eye on your crop from the moment you switch your lights to 12:12.
Outdoors is an entirely different story because your plants will begin flowering at a pre-determined genetic set point based on the shortening of the daylight hours as fall approaches. In this case, you generally would expect to see the first signs of flowering around the middle to end of August in the Northern Hemisphere, but some early blooming varieties can start this process as soon as July. And if you are growing auto-flowering strains then this can happen at absolutely any time, so keep your eyes peeled!
Location, Location, Location
While you will get better results, and more seed, by leaving your male to flower amongst the female(s) you wish to pollinate, sometimes this just isn’t an option or desirable. Perhaps there is only one plant (or even just one branch) in a crop of many that you wish to pollinate, or maybe you have a female that is slow to bloom and won’t be ready to receive pollen until after the male has already completed flowering. Or if you’re like me, maybe you just want to collect pollen for some future breeding scenario. In all of these situations, and many others I haven’t mentioned, flowering your male in a separate area and collecting the pollen makes good sense.
I keep a dedicated pollen tent for just such a purpose. I locate the tent well away from my female only grow rooms, and ensure that the exhaust from the ventilation system will not blow the pollen anywhere near the intake for my main grow facility. I also use HEPA filtered intakes for my female flowering rooms as well as the exhaust port on my male flowering rooms just to be sure.
A little pollen goes a long way, but I like to collect quite a bit if I’m going to the trouble. I usually let my males get quite big by growing them to 5 feet tall or larger, in 5-7 gallon containers, with multiple flowering tops. I’ll let the plant grow naturally until I start seeing the very first pollen sacks begin to open, at which time I employ a little bondage.
Set The Trap
Using modular plastic shelves on either side of the plant, I set a clean plastic nursery flat on each shelf and line with tin foil.
I then place my homemade screens over the top of the flats. I use these screens for drying bud, seed sifting, and pollen collection, so they come in handy for multiple uses. If you don’t feel like making your own, simple window screens can work well here.
I then split the plant down the middle, bending the branches over the top of the screens. Using some eye hooks and kitchen twine, I tie the branches down so that when they release their pollen, it will drop down through the screen onto the foil. Keeping the pollen dry is absolutely crucial: wet pollen is dead pollen! The screen catches the pollen sacks as they fall, and keeps them out of the collection tray where they would otherwise release their moisture into the drying pollen and ruin it.
Once you have strapped down your branches so they are overhanging your pollen collection screens, it’s a good idea to do some defoliation. What you’re trying to avoid here is having pollen drop from an opening sack and then collecting on the foliage. The foliage will transpire, and moisture will condense in the pollen and ruin it. You want the pollen to have a straight shot from the opening flower down into your collection tray. Strip all large fan leaves from the plant so you are left with only pollen sacks and small bud leaves.
Now that you have defoliated and strapped down your branches, you’ll want to arrange your lighting. I prefer using small LED panels for lighting at this stage because I can position them over each side of the plant for better efficiency as opposed to one centrally hung light. Ideally you’ll want to use a fan-less light, as pollen will get sucked inside the light housing by the fan. This could cause cross contaminate of pollen in future collections so be aware of that. I’m using a pair of crappy old 'blurple' Mars Hydro lights here, and yes they do have internal fans. They get blown out with compressed air and misted with 99% alcohol to kill any remaining pollen at the end of each collection. It's less than ideal, but they're just old spare lights that I'm not concerned about fucking up so they do the job.
Within 24 to 48 hours you will notice the branches will begin to reorient themselves towards the light and begin growing upwards once again. Pollen and pollen sacks will begin dropping down through the canopy, and onto the screen. Loose pollen will collect in the foil tray, with the majority of the chaff getting caught on the screens. See video below of the completed collection setup.
At this point you want to make absolutely sure that humidity is in check. I like to keep the tent at no more than 50% humidity (40% is ideal), and I use a dehumidifier just outside the tent’s air intake to ensure this is so. Remember, keep it dry or it dies!
You’ll also want to keep air movement inside the tent to a minimum. An oscillating fan will blow your pollen helter skelter, and reduce the amount of pollen collected in your trays. The cross-flow of air movement created by your intake and exhaust ports will provide plenty of air movement so no other fan is required.
A note on ventilation: For this single tent setup I use a 6” inline fan attached to a carbon scrubber with the dust sock installed for the powered exhaust, with an open passive intake. The sock will collect much of the stray pollen, with the carbon filter collecting some as well. However, some pollen will still make it through, which is why I rig a HEPA furnace filter to the exhaust port where it exits the building. This dramatically reduces the chances of stray pollen escaping.
Pollen will naturally fall from the plant as the male flowers (which resemble umbrellas) open and drop their contents. You will want to hasten this process by gently tapping the plant stalks once a day to encourage the pollen to release. Holding an electric toothbrush to the stalks can work well for this task as the vibration will shake the pollen loose.
Since pollen can accumulate in the foil trays quite quickly, you’ll want to empty them every couple of days to keep the pollen dry. Simply lift up the screens and remove the trays to collect.
Remove the foil liner and place on a perfectly flat surface like a kitchen countertop. Using a card, scrape the pollen into a pile.
You will notice some debris from the pollen sacks in amongst the pollen, and you need to remove this by sifting the pollen through a fine mesh tea strainer. Do this a few times to remove all the chaff, and then pour the cleaned pollen into a small glass bowl.
Leave the bowl open in an arid room (again, below 50% relative humidity) to dry completely for 5 days. It is advisable to place a piece of paper towel over the bowl and secure with an elastic band. This will allow it to breathe while keeping dust and contaminants out. Keep a toothpick nearby and stir it a couple of times per day to make sure you don’t get any moisture accumulation or clumping of the pollen.
As you collect more pollen every two to three days, it is advisable to dry them in separate containers. This ensures you have a couple of backups in case one container accidentally gets contaminated with moisture.
Storage and Use
Once all of my pollen is collected and dry, I pour it into small plastic containers and mix in some dry organic rice as a desiccant. It is important to use organic rice to ensure there is no chemical pesticide or herbicide residue that could kill your pollen. Each container is labeled and then placed in the freezer for long term storage. You can store your pollen in the fridge if you choose, but be aware that the temperature fluctuations caused by frequent opening and closing of the fridge can lower the long term viability of your pollen.
When I’m ready to use the pollen, I take out the amount I need and spread it on some tin foil to allow it to come up to room temperature. The unused portion goes immediately back into the freezer before it thaws. Any unused pollen that thaws and then is re-frozen will have substantially less viability, so only take out what you need.
Pollen collected and stored with care can remain viable for up to a year or longer. I have successfully fertilized female plants with pollen that is older than two years, but I have also had pollen that is only a few months old turn out to be completely sterile; it all comes down to eliminating contaminants from the pollen, keeping it bone dry, and storing it properly. A little luck helps too.