Understanding the Cannabis Light Cycle to Improve Yield The most important part of growing cannabis is getting a favorable yield that brings smiles and profit when it’s time to harvest. Growing When cannabis seedlings have grown their second or third set of serrated leaves they are usually hardy enough to flourish in direct sunlight. Learn when that is and how to do that now. What do I need to know about light cycles and flowering my marijuana plants? Plants keep getting bigger and bigger with long days, and start making buds when you give them long nights.
Understanding the Cannabis Light Cycle to Improve Yield
The most important part of growing cannabis is getting a favorable yield that brings smiles and profit when it’s time to harvest. Growing cannabis, however, can sometimes be challenging for beginners . The success of your marijuana grow frequently depends on one crucial factor: lighting.
Lighting is crucial when you are growing your cannabis, whether indoor or outdoor. The light cycle you use for flowering cannabis directly correlates to a crop’s quality and overall yield. Yes, you need light to grow your cannabis, and here is what you need to know about the cannabis plant light cycle.
There are two stages of cannabis growth where it is important to strategically monitor your light cycles. These are:
- The vegetative stage
- The flowering stage
The Vegetative Stage Light Cycle
This is the stage where your plants are growing. This stage is very vital for the success and health of your cannabis plant. At this stage, the stems and leaves of the marijuana plants start growing larger and taller. However, also at this stage, the cannabis plant doesn’t produce any buds and you will have to control the shape and size of your plant. That is where the cannabis light cycle comes in: the light for your plants can be manipulated at this stage to yield better growth. The more lighting your cannabis plant receives, the better their growth and future yield.
When marijuana plants are in the vegetative stage, keep them under a minimum of 18 hours of growing light (also known as 18/6). But if you are one of those growers that would like their plant to grow as big as possible, then you may keep them under 24 hour (24/0) indoor light.
Cannabis plants don’t start developing flowers until they start receiving 12 hours of continuous darkness. Otherwise, they will continue to remain in the vegetative stage. As long as your cannabis plants are getting about 13 hours of light (or more) every day, you can keep your plants in this stage forever.
Indoor Vegetative Stage
Note that while in the vegetative stage, light is not the only means of growing large cannabis plants. If you are growing your plants indoors, you will need a well maintained grow room with a high ceiling.
Also, it’s important to note that certain cannabis strains (like Northern Lights and Jack Herer, for example) grow higher yielding crops even without such manipulations.
Outdoor Vegetative Stage
Typically, most growers would start their cannabis plants indoors under lights before moving them outside to grow under the sun. Most growers would usually start either cutting clones or starting seeds during March or April, and would keep them under 18 to 24 hours of constant light before moving them outside in the early period of May or June.
So, if you have plans to grow your cannabis outside, it can be helpful to first keep them inside until all forms of danger like frost, for example, have passed. A sudden drop in temperature or a late spring snowfall can kill your cannabis crop outright.
But, once such risks are over, your plants will be in vegetative stage outdoor from the late period of spring down to late summer.
The Flowering Stage Light Cycle
For your plants to move from their vegetative stage to the flowering stage, they will need to be exposed to 12 or more hours of darkness each day to start flowering.
Flowering Indoor Cannabis
Most growers that grow their plants indoors begins from the point of 12 hours of darkness immediately the plants have reached the desired size and shape during their vegetative stage. Usually, most growers prefer an indoor vegetative period of 4-8 weeks under a 24/0 or 18/6 light period.
To grow cannabis successfully indoor, you need to mimic the natural growth pattern. When you grow your cannabis outdoor, they start to develop buds (flowers) as the days gets shorter, and they receive a minimum of 12 hours of complete darkness. To do this, just switch your light usage from 18 to 24 hours of good sunlight daily down to 12 hours of light and also of 12 hours of darkness for the cannabis life cycle.
Flowering Outdoor Cannabis
If you have plans to grow your plants outdoors, allow nature to take its course. During this time period, the cannabis plants will start to produce flowers naturally on their own, which usually happens after the 21st of June, as the days start getting shorter.
Of course, the plants will not stop growing or developing flowers at this particular instance. On average, the plants start doubling up in height and shape after they begin the flowering stage — this is true for both indoor and outdoor plants. However, make sure your cannabis plants are NOT exposed to light during the 12 hours they are supposed to be in darkness. Take care: floodlights and even street lights can seriously disrupt the flowering period.
Scheduling Your Light Cycles for Maximum Yield
Are you planning to grow your cannabis indoor or outdoor? It is crucial you understand light cycles for cannabis seedlings so you can define the best light schedule for your crop. If you can follow up with a beautiful lighting plan, you will get maximum yield during harvest.
If you are growing your cannabis plant indoors and you do not have any issue with room height or space, then you should allow your plant to remain under 24/0 or 18/6 light schedule during the vegetative stage. This should last for 60 days, which is the best time to grow more flowers.
On the other hand, if you plan to grow outdoor, your light cycle for flowering cannabis should also be scheduled for 18/6 or 24/0, but you will want to first keep them inside until all unfavorable conditions like freezing temperatures and frost have passed. After that, you can safely bring them out and allow them to grow and flourish naturally under the open atmosphere, relying on the sun’s natural light cycle.
From the moment you have successfully crossed the vegetative stage of your cannabis plants, from 3 to 6 months, get ready to reap a bountiful harvest from your seedling efforts.
There are a whole lot of benefits to growing your own cannabis. However, you can only get the best harvest and therefore the most benefit from homegrown cannabis by knowing the various light cycles involved during the planting and growing of your crop.
You will have to do some experimenting to get truly familiar with the cannabis light cycles we have discussed. If you are cannabis cultivation newbie, however, you can stick to the tips above and rest assured that you will find success along the way.
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When can seedlings be put under lights or in the sun?
Not sure whether to grow your cannabis seeds in the sun or under lights? This article explains how much light you need, how to prevent your seedlings from falling over, and when to plant them outside.
“When can cannabis seedlings be put under lights or in the sun?” is a common and sensible question that is often asked by novice cannabis enthusiasts after germinating seeds indoors under lights.
For those who are growing indoors, cannabis seedlings may be put under lights as soon as they emerge from the soil or growing medium.
How much light for cannabis seedlings?
When using HID lighting (usually a metal halide lamp), young seedlings should be kept at least 50cm from the bulb.
With compact fluorescent lamps (usually 100w or more), a distance of around 15cm should be maintained between the top of the young seedlings and the bulb.
If using normal fluorescent tubes (18-36w), seedlings can be kept within a few centimetres of the light source.
Cannabis seedlings growing under lights should always be given a gentle breeze from an oscillating fan (a small household fan on the lowest setting is fine), as constant gentle movement will strengthen their stems significantly.
Are your cannabis seedlings falling over?
If cannabis seedlings grow tall and then fall over, this is almost always a result of growing in an environment with static air.
Seedlings intended for outdoor growing should be kept by a sunny window for the first week or two after emerging from the soil.
When they have grown their second or third set of serrated leaves (after the the round cotyledons that initially emerge from the seed) seedlings are usually hardy enough to flourish in direct sunlight.
When to plant your cannabis seedlings outside?
If outdoor temperatures are suitable, seedlings may be acclimatised to direct sunlight by giving them progressively longer daily exposure to outdoor conditions.
Starting with about three hours outside, at the sunniest time of day, seedlings can be given an extra hour of outside exposure each day, so that within about two weeks they can be left outdoors permanently.
Laws and regulations regarding cannabis cultivation differ from country to country. Sensi Seeds therefore strongly advises you to check your local laws and regulations. Do not act in conflict with the law.
Cannabis Light Schedules: Vegetative Stage vs Flowering Stage
Cannabis plants keep getting bigger and bigger with long days, and start making buds when you give them long nights.
Cannabis is a “photoperiod” plant, which means the amount of light received each day decides when the plant starts flowering or making buds. This article explains how much light a day your photoperiod cannabis plants need to grow and start budding, so you get to a happy harvest day. What about auto-flowering strains?
Vegetative – Seedling or clone leads to Vegetative Stage –
Give 18-24 hours of light a day
Flowering – Flowering (Budding) Stage leads to Harvest –
Give 12 hours light & 12 hours dark each day
Seedling or Clone
While not technically a “stage,” all grows start with cannabis seeds or clones.
Plant your seeds or clones when you’re ready to start growing! What are clones? https://www.growweedeasy.com/cloning
Some outdoor growers start their plants indoors to give them a headstart before putting plants outside.
If you’re growing cannabis outdoors with seeds, you should wait until a few weeks after the spring equinox to put your seeds outside. In the northern hemisphere this means seeds go outside in-or-after April, In the southern hemisphere seeds go outside in-or-after October.
For growers starting with cannabis clones, generally you should wait a few weeks longer than with seeds. Cannabis clones are more prone to flowering early outdoors than seeds, so you might want to put your clones out in late Spring or early Summer. (What are clones?)
If you live in a cold climate, you must also wait until after the last frost before putting your plants outside. Freezing temps will kill cannabis plants. Strain choice is very important. Some strains flower earlier than others. For outdoor growers in cold climates, it’s important to make sure you grow a strain that is matched up with your local weather, so that plants are ready for harvest before temperatures drop.
The vegetative stage is one of the most important parts of the life of your cannabis plant.
The vegetative stage is the growing stage of the plant. When in veg, cannabis plants grow bigger and taller, growing only stems and leaves. As a grower, you are able to control the size and shape of your plants in the vegetative stage using simple training methods.
During the entire vegetative stage the plant does not produce buds at all. It only grows stems and leaves. During the vegetative stage plants tend to grow very fast, especially when conditions are right.
What keeps cannabis in the vegetative stage?
Short nights keep cannabis plants in the vegetative stage. You can keep a cannabis plant in the vegetative stage for basically forever as long as the plant continues to get short nights (shorter than 1s-12 hours, depending on the strain).
Cannabis will stay in the vegetative stage as long as the plant gets short nights (less than 11-12 hours of darkness each day)
Whether you’re growing indoors or outdoors, you must make sure your cannabis plants get at least 13 hours of light each day to stay in the vegetative stage. If your plant gets a few long nights, it may start budding before you want.
The plant can receive as much as 24 hours of light a day while in the vegetative stage. Many indoor growers provide 18-24 hours of light a day (known as 18-6 or 24-0 light schedules) during the vegetative stage to encourage faster vegetative growth.
Don’t want to worry about light schedules? For growers that don’t want to pay attention to light schedules, there are auto-flowering strains of cannabis, which will automatically go through their whole life in about 3 months no matter what light schedule is provided. For some growers, an auto-flowering strain may be more simple than a traditional (photoperiod) strain.
Most indoor growers provide 18-24 hours of light a day (known as 18-6 or 24-0 light schedules). Giving your cannabis plants more hours of light each day in the flowering stage will encourage faster growth.
Lingo: When a grower provides 18 hours of light a day and 6 hours of darkness, this is commonly known as the 18/6 light schedule. For 24 hours a day, this is referred to as the 24-0 light schedule.
As long as your plant is getting plenty of light a day, your plant will automatically stay in the vegetative stage from late spring until late summer. Every strain is a bit different.
Cannabis starts budding when plants get at least 12 hours of uninterrupted darkness each night. After plants start budding, they must continue to get long dark nights until harvest or they may revert back to the vegetative stage.
Indoors most growers put their plants on a 12-12 schedule to initiate flowering. Outdoors the plant will naturally start budding in late summer when nights are growing longer and longer as winter approaches. Just make sure plants aren’t exposed to light during their dark period!
What is 12-12 Lighting?
The indoor grower will need to artificially induce flowering/budding in plants by changing the light schedule so the plant receives only 12 hours of light a day, and 12 hours of uninterrupted darkness.
Once the plant is changed over to the flowering (12/12) light schedule, there is generally another 6 weeks-5 months (average 2.5 months) before the plant’s buds are ready for harvest.
Outdoor growers wait until their cannabis plants start naturally flowering on their own, usually after mid-summer when days start getting shorter than 12 hours.
It’s important to make sure plants aren’t exposed to light at night during their dark period, even street lights or spotlights, as this can prevent cannabis plants from flowering properly.
Growing Indoors? Not Sure When To Switch To Flowering?
So indoor growers have a choice to flower their plants whenever they want… When is the best t ime to start flowering your cannabis indoors?
The real answer is that it’s a matter of personal preference and also depends on what end result you’re looking for. There are two major considerations when choosing the right time to switch to 12/12, the age of the plant and the height of the plant:
Age: Some growers feel that a marijuana plant which has been grown from seed will not produce as many buds or have enough resin production if the plant is not given at least 60 days in the vegetative stage to mature before it’s changed over to the flowering stage. This is not true. many growers initiate flowering soon after germinating a seed in order to keep plants small and short. This is often called “12-12 from seed.” Just remember, no matter what you do, a young cannabis plant will not start flowering until it is 2-3 weeks old. Even if you put a seed on a 12-12 schedule from the beginning, it will not start properly budding for about 3 weeks. When growing with cannabis clones, age is not an issue and growers can switch directly to flowering once your clone has established roots. This is because even though a clone may be small, it’s still a ‘mature’ plant since it is made of a piece from a mature plant. Rooted clones tend to grow much faster for the first few weeks than plants grown from seed. In any case, age is not much of an issue, and you should switch your light schedule at the time that best fits your needs.
Height: A general rule is that your marijuana plant will double or triple in size during the flowering stage from the point where you first change over the light schedule to 12/12. Some plants will grow more, some will grow less, but a good rule of thumb is to change your light schedule over to flowering when your plants have reached half of their final desired height. Bending, known as “LST” or “low stress training” can be used to control colas that get too tall. Simply bend too-tall colas down and away from the center of the plant. Some growers will even slightly break or “supercrop” branches to get them to bend at a 90 degree angle. For those growing in a small space, height may be the primary concern. However, there are many techniques available to grow a short, bushy weed plant or basically train your cannabis plant to grow into any shape you want.
Here’s an example of LST to keep a plant short:
In optimal conditions if height and space is not an issue, you would probably want to vegetate your cannabis plant for 60 days or more before switching it over to flowering. This gives your plant plenty of time to grow big (so you get bigger yields), and allows new growers to dial in their grow before plants enter the sensitive flowering stage. In the vegetative stage, it is easy to recover from problems, but problems are a lot more serious in the flowering stage, where mistakes can dramatically hurt your final yields.
Giving cannabis plants more time in the vegetative stage, and taking time to train them to fit your space, will give you the best final yields. However, if space is tight, then it’s better to switch when the plant is half the final desired height, or even to just attempt to flower your cannabis plant straight from seed.
After the vegetative and flowering stage are over, it is time to harvest your plants!