How To Increase Your Marijuana Yield
When people begin looking into growing marijuana for the first time, one of their main concerns is maximizing their yield. This makes sense, because who would want to invest in the equipment, tools, effort, and time necessary to grow marijuana if they only get a disappointing yield out of it at the end? This article covers some of the basic ways to ensure maximum yield.
Generally speaking, you should make sure that the temperature of your grow area stays between 72 and 78 degrees Fahrenheit. If the temperatures reach 85 or higher, or 65 or lower, you will begin to notice changes in your plants’ growth, as it will slow down or stop altogether.
To properly maintain a consistent and healthy temperature, make sure you have a digital thermometer to get the most accurate measurements of temperature in the room, and be sure you have invested in the right equipment to heat or cool your grow room as needed. If you are an outdoor grower, then the strain you pick will make a bigger difference, as that will determine how well your plants deal with the natural seasonal temperatures.
Humidity can do a lot to help marijuana plants grow and thrive. When your plants are in their vegetative and flowering phases of growth, try and keep the levels of humidity between 45% and 55%. Towards the end of your marijuana plants’ flowering phase, specifically during the last two weeks of it, drop the humidity to make it less likely that the thick, juicy buds don’t develop any mold.
Moisture of the grow medium
Whatever grow medium you are using to grow your marijuana plants in, try to ensure that it never gets soggy. Instead, it should be some sort of soil mix (or a mix of whatever type of medium you are using) that drains quickly. If you have a hydroponic grow setup, on the other hand, it needs to be aerated plenty. Moisture can be a problem because it might lead to things like mold, fungi growth, root rot, and other issues that will affect the yield of your plants.
Just like people and animals, marijuana plants need nutrients to grow and stay healthy too. The main ones you will have to worry about are nitrogen (N), phosphorus (P), and potassium (K). Any fertilizers you buy are going to list the “NPK” value that illustrates the ratio of each of these nutrients. This is important because your marijuana plants will require the nutrients in different amounts during their various stages of life.
Generally speaking, your plants will need more phosphorus than nitrogen and potassium in their flowering phase. Remember to always start off slow with nutrients, even if you are using organic mixtures. Begin at half strength and work your way up from there.
Light is one of the biggest concerns you should have when setting up your grow room or choosing an outdoor grow area. It’s also an aspect of marijuana growing that is commonly done poorly. Generally speaking, more light means more growth. But that isn’t where the equation ends. More light also means you will need more water, nutrients, and CO2.
The lighting also needs to be set up correctly in your grow room. One essential part of this is reflecting the light as much as possible, directing it straight into your plants’ foliage. The lights should also be located not too far away from the tops of your plants, but a great enough distance so that they won’t singe their top leaves. Do a heat test by placing your hand under the light, where the top of the plant is. If your hand is getting uncomfortably hot, then the light is too close to your plant.
The other thing to remember is what kind of lights you are using. Marijuana requires light of a certain spectrum, depending on their growing stage. For the vegetative stage, go with a metal halide (MH) or a cool white fluorescent because they supply enough of the blue spectrum of light, which mimics the normal spring and summer sun. Once your plants reach the flowering stage, however, they should be given light that is more in the red color. High-pressure sodium (HPS) lights or warm fluorescent lights should do the trick.
MH or HPS lights are recommended as the tried and tested lights over fluorescent lamps, which are still somewhat new to the marijuana growing world. MH and HPS lights are proven to lead to good results unless you are growing hundreds and hundreds of plants at a time.
You would be surprised at how important genetics are when trying to get a good yield out of marijuana plants. This is perhaps the most commonly ignored aspect of marijuana growing by new growers, as they underestimate how important it really is. Some strains simply are designed to produce far more (and bigger) buds than other strains, so you need to know what you are buying.
Of course, purchasing the right strain isn’t all you have to do – it just raises the potential for how much yield you could achieve. Be sure to have a thorough understanding of the strain of marijuana seed you purchased so that you know exactly what type of growing environment to give it. Research leads to high yields (compared to growers who do no research), so don’t be afraid to take the time and look up all the information you need.
Carbon dioxide (CO2)
If you are growing your plants outdoors, you can skip this section as they will already have enough CO2. For indoor growers, however, CO2 becomes an important factor in growing your marijuana. The best way to do this is by installing an exhaust system. Your exhaust system should be good enough to replace all the air inside every five to ten minutes. That way you will know that your plants will have fresh CO2 coming in regularly. Some growers opt to buy products such as CO2 buckets to add extra CO2, but this becomes rather expensive.
When thinking about sizing, you should be considering how big the marijuana plants will get, how large their root systems will grow, and how large their growing container needs to be. Keep in mind that a longer vegetative phase means a higher yield, as the plant has time to develop and mature more fully before entering the flowering phase.
The roots, though you can’t usually see them, are equally important in the yield that your marijuana plants achieve. For that reason, your plants’ roots are going to need lots of room to grow and thrive. Measure your plants, and give them one gallon of soil per every foot of height that they are. Plan ahead, because transplanting marijuana plants can be a hassle (and shocking for the plant).
Plenty of growers swear by less conventional ways of growing marijuana. Whether they use vertical gardens, Scrog, Sog, low-stress training, or high-stress training such as topping, they have found a number of methods that are equally as effective as conventional methods. You can also add additives to your plants such as B1, kelp, or enzymes. If this is your first time growing, however, we recommend trying it the “normal” way first and seeing how that goes before trying alternative ways of growing.
Additional ways to help your plants get better and bigger buds is by keeping the nighttime temperature warmer, as well as getting more amounts of oxygen to your plants’ roots (such as growing them using aeroponics).
Aquaponics is another alternative option. It involves giving your plants nutrients with the waste water from aquatic animals. Essentially, that means you will be growing your plants hydroponically with fish swimming around. It is entirely sustainable, which is a huge appeal to many growers. It produces a high-quality result and will keep your conscience pure because your growing operation is Earth-friendly.
Written by Robert Bergman, founder of ilovegrowingmarijuana.com. Robert has been passionately exploring and experimenting with cannabis seeds for over 20 years and shares these insights to educate growers avoid mistakes and to fully capitalize on a bud’s potential and get the most out of a marijuana plant.
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Indoor grow manuals always mention the importance of using reflectors to help take advantage of every ray of light your growlamp puts out, but most amateur growers don’t realize exactly how much this really matters. Using some simple measurements and mathematical approximations, HIGH TIMES has determined roughly how much light you can save with some cleverly hung reflectors.
Cannabis ferociously devours light on a daily basis making it one of the most important limiting factors for yield. Simply put, the more abundant and better your light source is, the higher your yield. Without needing to hang more electricity-guzzling, heat-generating lamps in your garden, good reflector placement can increase light intensity in the canopy by up to 60%.
What, may you ask, do we use to measure light intensity for the purposes of plant growth? Photosynthetic photon flux, or PPF, is the sum of all the photosynthetically-active photons between wavelengths 400 nm (blue) and 700 nm (red), which roughly coincides with the spectrum of visible light humans can see. PPF is measured in units of micromoles of photons per second, μmol/s. Photosynthetic photon flux density, PPFD, is a measurement of the density of the photon flux falling over a given area and has units of μmol/s/m2. The daily light integral (DLI) is the sum of all the photosynthetically-active photons a given area receives in a day, and has units of moles/day/m2.
For the purpose of measuring plant-usable light that covers your garden’s canopy, PPFD is unit of choice. On the other hand, DLI is a tool that botanists use to compare the light requirements of different plants, and its what greenhouse growers measure to assess how much supplemental lighting they may need on shady days. For example, orchids only require a modest 8 moles/day/m2 for high quality growth, while tomatoes need to bask in up to 30 moles/day/m2. In the cold, dark month of December, Northern California experiences 10-15 moles/day/m2, but in June, this number can go as high as 55 moles/day/m2. Check out this publication for DLI maps of the USA, and this publication for a diagram of the DLI requirements of various common greenhouse plants.
If we knew what the DLI requirement was for cannabis we’d tell you; we’d shout it on the mountain tops from Malibu to Morocco, but the fact is nobody knows for sure. For all intents and purposes, it takes around 25 moles/day/m2 to yield decent harvests, but the more light the better. If a cannabis plant needs 25 moles/day/m2 over an 18 hour light-cycle, this puts the hourly requirement at 1.38 moles/hour/m2. Divide this number by 0.0036 and you get the PPFD your lamps need to deliver: 385 μmol/s/m2.
So how much can reflectors increase the PPFD under an HID growlamp? We put it to the test with HIGH TIMES’ own spectroradiometer. A 400 W cool-tube HPS lamp (with a built-in reflector directly behind the bulb, but not on the sides) produced a PPFD of 148 μmol/s/m2 directly underneath it at three feet away. Simply holding two reflectors on each side of the cool-tube (so that the light projected itself on the floor with a 120° angle) raised the PPFD to 235 μmol/s/m2, a 59% increase. The tighter the angle the reflectors force the light into, the higher the PPFD and the higher your yield will eventually be.
The light from your growlamps should be utterly concentrated to the plants, if any part of it spilling onto the floor or the walls means its not hitting the plants, and they won’t receive their daily dose of light they need for productive growth. In the diagram above you can see a lot of wasted light. As is, those plants under a 400 W HPS light will only receive a DLI of roughly 9.8 moles/day/m2. With just a few reflectors, this DLI could go up to 26 moles/day/m2 without any additional electricity.
Simply coating the walls of the growroom with aluminum foil doesn’t fix this problem, the beams need to reflect directly onto the canopy. Reflectors made using aluminum foil will do the job for cheap, but that foil only reflects around 80% of the light it gets. To really get the 90 -95% reflectance you want, invest in a legitimate reflective surface. Don’t let your yields suffer due to wasted light, get the most out of your lamps and your little garden will be more productive than you ever imagined.
Photo Credit: VortexFarmacy
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