If you have ever grown cannabis plants outside, you may have felt like you were in a bitter race to see your plants reach their finish stage before the sun really starts to fade away, or even worse, the rain and morning dew arrive causing that fatal bud rot. Northern Californian farmers who have been working with cannabis plants on a large scale for three or more generations have come up with some fantastic ways to get their plants to finish and ready to chop before these very real problems set in.
Pic: SappFire Seeds in NorCal with light deprivation in a polytunnel.
The thought of losing a crop to mould is enough to put even the keenest of gardeners off growing some of their favourite herb. The disappointment diminishes so much of the excitement you had throughout the three or even four months of growing such a glorious plant when you realise you've got a rotten jar of flowers.
So how do we hack the summer sun to ensure we get top quality cannabis without the end of summer risks?
Northern Europe still has 16 hour days in the middle of June and start of July but 12 hours of light and 12 hours of darkness is the photoperiod that your plant reads as a signal to start flowering and produce seeds to ensure the survival of the species. We don’t want seeds in our cannabis but we do want to initiate that flowering process earlier than the start of August because it takes at least 8 weeks of that 12/12 light to reach full fruiting maturity.
So, we need to force our plants to flower earlier than they would naturally do so. There are a couple of ways to do this. It does require a little bit more effort than just going out and watering your plant every day, so make sure that you have the time and dedication to do this every single day.
How do we create 12 hours of darkness?
The first thing to do is pick the rough date you want to harvest. Let's say August 31st for example. We then count back 8 weeks from this date (or our recommended flowering time) and just to be safe incase we need to give it any extra time, we add on a week putting us on 29th of May. So by 29th of May you need to have a plant that is as big as you would like to start flowering. But how big should that be?
The size of your plant needs to match the size of the cover you are going to use to trick your plant into thinking it’s flower time. You will need at least 4 weeks for your cannabis plant to be big enough before you think of starting your forced flower process. Your plant could stretch 1 - 3 times the size during flower so take this into consideration.
If you are growing a very small plant or a few small plants you might find that a dustbin is perfectly good for putting over the top of each plant for 12 hours at your chosen time. The risk you have here is if the plant over grows the size of the bin either in width or height. There's also not much ventilation for your plants to respire and expire which will make the moisture build up inside. As you can see this isn't that ideal for anything that big, although it does prove the concept if you just want to give it a try. But we need to be a bit smarter for something to get any yield.
If you are growing something a little bigger, or a few different plants, erecting a gazebo and making it light proof from the inside and moving it over the plants each night at the time you have chosen can work.
Pic: @FireKeeperFarms with a medium scale light deprivation using covers manually.
You may already be growing in a polytunnel or greenhouse? If this is the case making a covering out of light blocking material such as dark tarpaulin can work great. Just be sure to check for light leaks if you’re using multiple tarps together.
If you don't have a polytunnel or greenhouse, you can also pick the plants up and move them into the gazebo, or a shed/garage at the chosen time. The risk you have here is damaging the plants if they become too big in flower. Just remember to be careful at all times, not just for the plants but you don’t want to injure yourself lugging heavy pots around.
How do I know it's working?
Between 7-10 days you should start seeing your first flowers shaping up in the form of the white hairs also known as pistils. Remember to be patient and let nature take its time. And don't touch the buds!
You may find that some or all of the pistils turn pink and this can be from a combination of colder temperatures and genetic factors - there's nothing to worry about though and it looks pretty cool.
Must Do’s
Once you pick your light dark cycle - stick to it! This is a daily task not to be slack about. Your plant’s day/night rhythm is not to be messed with or else you could risk not getting any flowers OR ending up your plants turning hermaphrodite and seeding your crop. If you pick 6am-6pm at the start, that’s when you will finish so make sure it’s something you are disciplined enough to stick to. You are acting like the timer for your light if you were growing indoors.
Make sure your dark area is as sealed from light as possible. Check regularly for light leaks by getting inside and looking for light getting in and seal it up appropriately.
Inspect regularly for mould and pest infestations. Outside these can happen over night (or day) and escalate very quickly into a "is my plant still ok" situation.
If you're using a gazebo make sure it doesn't blow away over night! Peg it down.
If you are growing seeds that recommend a longer flowering time make sure you calculate that rather than just the standard 8-9 weeks as suggested.
Always remember to stay safe and respect your neighbours.
Related Post
If you have ever grown cannabis plants outside, you may have felt like you were in a bitter race to see your plants reach their finish stage before the sun starts to fade away. Or even worse, your work may be cut out to finish before the rain and morning dew arrive, causing that fatal bud rot. Outdoor growers in Northern California who have been working with cannabis plants on a large scale for three or more generations have devised fantastic ways to get their outdoor plants to finish and ready to chop before these genuine problems set in. Of course, you can now use Early/FAST Cannabis strains. But if you want to stick to growing what you know, one of these ingenious methods is known as force flowering, and you can do it, too!
Why Use The Force Flowering Method?
The thought of losing a crop to mold is enough to put even the keenest outdoor growers off growing some of their favorite herb. The disappointment diminishes so much of the excitement you had throughout the growing season of three or even four months tending to such a glorious plant when you realize you've got a rotten jar of flowers.
So, how do we hack the summer sun to ensure we get top-quality outdoor cannabis without the end-of-summer risks?
The Northern Hemisphere still has around 16 hours of sunlight in the middle of June and the start of July, but 12 hours of light and 12 hours of darkness is the photoperiod that your plant reads as a signal to start the flowering stage and produce seeds to ensure the survival of the species. We don’t want seeds in our cannabis, but we do want to initiate that flowering process earlier than the start of August because it takes at least eight weeks of that 12/12 light cycle to reach full fruiting maturity.
So, cannabis growers need plants to leave the vegetative stage and enter the flowering period earlier than they would naturally do so. There are a couple of ways to do this. It requires more effort than just going out and watering your plant every day, so make sure you have the time and dedication to do this every day.
How Do We Create 12 Hours Of Darkness Outdoors?
The first thing to do is pick the rough date you want for harvest time. Let's say late summer - August 31st, for example. We then count back eight weeks from this date (or the strain's recommended flowering time), and just to be safe, in case we need to give it any extra time, we add on a week, putting us on May 29th. So, by May 29th, you need to have a plant as big as you would like to start flowering. But how big should that be?
The size of your plant needs to match the size of the cover you will use to trick it into thinking it’s flowering time. You will need at least four weeks for your cannabis plant to be big enough before you think of starting your forced flower process. Your plant could stretch 1 - 3 times its size during flowering, so take this into consideration.
If you are growing a very small plant or a few small plants, a dustbin/trash can is perfect for putting each plant over the top for 12 hours at your chosen time. The risk you have here is if the plant overgrows the size of the bin, either in width or height. There's also not much ventilation or airflow for your plants to respire and expire, which will make the moisture build up inside. As you can see, this isn't ideal for anything that big, although it proves the concept if you want to try it. But we need to be more innovative with force flowering for something to get yield.
If you are growing something a little bigger or a few different plants, erecting a hoop house or gazebo, making it lightproof from the inside, and moving it over the plants each night at the chosen time can work perfectly.
You may already be growing in a polytunnel or greenhouse. If this is the case, making a covering out of light-blocking material such as a shade cloth or dark tarpaulin can work great to force flowering. Just be sure to check for light leaks if you’re using multiple tarps together to create the necessary blackout effect.
If you don't have a polytunnel or greenhouse, you can pick the plants up and move them into the gazebo or a shed/garage at the chosen time. This also works to force flowering. The risk here is damaging the plants if they become too big in flower. Remember to be careful at all times, not just for the plants, but you don’t want to injure yourself lugging heavy pots around.
How Do I Know If Force Flowering Is Working?
Between 7-10 days, you should start seeing your first flowers shaping up in the form of white hairs, also known as pistils. Remember to be patient and let nature take its course. And don't touch the buds! You may find that some or all of the pistils turn pink, which can be from a combination of colder temperatures and genetic factors - there's nothing to worry about, though, and it looks pretty cool.
Force Flowering Must-Do’s
When using the force flowering/light dep technique, once you pick your light schedule- stick to it! This is a daily task not to be slack about. Your plant’s day/night rhythm is not to be messed with, or else you could risk not getting any flowers OR ending up with your plants turning hermaphrodite and seeding your crop. If you pick 6am-6pm at the start, that’s when you will finish, so make sure it’s something you are disciplined enough to stick to. You are acting like the timer for your light if you were cultivating cannabis with an indoor grow. You can't treat yourself to a long lie on weekends with this.
Make sure your dark area is as sealed from light as possible. Check regularly for light leaks by getting inside and looking for light getting in, and seal it up appropriately. Inspect regularly for mold and pest infestations. When outdoor growing, these can happen overnight (or day) and quickly escalate into a "is my plant still ok?" situation.
If you're using a gazebo, or a polytunnel-type construction to extend your dark period, make sure it doesn't blow away overnight! Peg it down, and make sure it's secure. All your efforts will be in vain if your structure moves. And last, but by no means least - if you are growing cannabis seeds that recommend a longer flowering time, make sure you calculate that rather than just the standard 8-9 weeks as suggested.
Force Flowering - A Secret Weapon For The Outdoor Grower
Force flowering is a handy - no - actually, an ingenious method of tricking your cannabis plants into finishing earlier. By following the steps outlined above, you can outsmart common cannabis growing problems, such as mold, that come with seasonal changes and can ultimately wreck your hard-earned success. As with all forms of cannabis cultivation, keep a close eye on your plants and be prepared to make changes if needed. Forcing early cannabis flowering is relatively straightforward as long as you stick to the rules, avoid unnecessary light exposure, and stay consistent with your dark times and daylight hours. Good luck!
