Complete Guide to Growing Cannabis

We proudly present a complete guide to growing cannabis. Here you will find every aspect of growing our favorite plant. It’s interesting how something so simple as growing an herb can become really challenging and competitive, to say the least. After all, we all want the best possible yields in the end. Without further ado let’s learn how to grow cannabis.

Key Takeaways

• Growing cannabis requires careful consideration of the growing space, lighting setup, and ventilation to ensure optimal plant health and yield.
• The quality of light is a crucial factor in cannabis cultivation, with HID, CFL, and LED being popular lighting options.
• Proper ventilation is necessary to maintain the right temperature and provide fresh air for the plants.
• Controlling and monitoring environmental factors like light cycles, temperature, and pH levels are essential for successful cannabis cultivation.
• Choosing the right growing medium, such as soil or hydroponics, affects plant growth and nutrient uptake.
• Proper germination and cloning techniques help ensure healthy plant starts.
• Training techniques, like Low-Stress Training (LST) and topping, can help maximize yields and shape plant growth.
• Transitioning to the flowering phase requires a 12/12 light cycle, and proper timing for harvest is critical for potent and flavorful buds.
• The drying and curing process is crucial for preserving the quality, aroma, and taste of the harvested buds.
• Paying attention to environmental conditions, nutrients, and overall plant health is essential for successful cannabis cultivation.

Grow Space

If you are skilled and creative enough, you can create the growing space yourself. It can be, for example, a closet, freezer, PC case, or similar, or you can simply buy a ready-made “grow box.”

When designing your space, you will need to consider not only the amount of space needed for your plant(s) but also your lights, ducts, fans, and other equipment, as well as leave enough room for work. Plants can double or even triple in size during the early flowering stage (stretch), so make sure to provide enough space for the tops!

Ensure that your space is easy to clean and disinfect. Cleanliness is essential for indoor cultivation. Surfaces should be smooth; carpets, curtains, and raw wood are difficult to clean, so avoid these materials if possible. The growing space should not be too bright and airy; slight light leakage during dark periods can confuse your plants and may lead to hermaphrodites. You need to carefully monitor your plants, and it’s important to check them every day. It is recommended to choose a cool and dry space with proper access to fresh air from the outside.

Light

The quality of light will be the number one environmental factor affecting the quality and quantity of your yield. Therefore, it’s a good idea to choose the best lighting setup you can afford. Here’s a brief overview of the most popular types used:

HID (high-intensity discharge)

An industrial standard widely used for a combination of output, efficiency, and value. They cost a bit more than fluorescent lights but produce much more light per unit of electricity used. On the other hand, they are not as efficient as LED lighting, but they are still significantly cheaper.
Two main types were used:

Metal Halide (MH)

Produces blue-white light and is generally used during the vegetative stage.

High-Pressure Sodium (HPS)

Produces red-orange light and is used during the flowering stage.

In addition to the bulb, HID lighting requires a ballast and reflector. Some ballasts are designed for use specifically with MH or HPS bulbs, while many newer designs can run both. HID bulbs produce a lot of heat, so a good cooling and ventilation system is necessary.

CFL and Other Fluorescent Lights

Fluorescent fixtures, especially those using large (HO) T5 bulbs, are quite popular for small-scale “hobby growers” for several reasons:

• They are usually cheaper to set up because the reflector, ballast, and bulbs are included in one package.
• They do not require a cooling system as they generate significantly less heat compared to HID.
• The main drawback is that fluorescent lights are less efficient, producing about 20-30% less light per watt of electricity consumed.
• Space is also a concern, as you will need approximately 19 long T5 (HO) bulbs to match the power of a single 600 W HID bulb.

LED (Light Emitting Diode)

LED technology has been around for a while, but it has recently been adapted to create super-efficient indoor growing lights. The main drawback of LED lights is their cost, as well-designed fixtures can cost 10 times more than comparable HID lights.

The advantages are that LED diodes last longer, consume far less electricity, generate less heat, and the best designs produce a fuller spectrum of light, which can result in higher and higher-quality yields. Unfortunately, there are many unreliable LED lights produced and marketed by manufacturers, so do some research and read product reviews before spending your hard-earned money.

Ventilation

Ventilation is important as plants need fresh air to thrive, and carbon dioxide (CO2) is essential for the process of photosynthesis. This means you will need a constant flow of air circulating through your room, which can easily be achieved by using an exhaust fan positioned at the top to remove warmer air from the space. You need to ensure that temperatures stay within a comfortable range for your plants:

22 – 30 °C (72 – 86 °F) while lights are on
18 – 21 °C (64 – 70 °F) when lights are off

The size and capacity of your exhaust fan will depend on the size of the growing space and the amount of heat generated by your lighting system. People living in warmer regions may often turn on their lights at night to maintain a comfortable temperature throughout the day and night. It is recommended to set up the lights, turn them on for a while, and then determine how much airflow you need to maintain a pleasant temperature for your plants. This will help you choose a suitable exhaust fan for your needs.

If the odor from your plants becomes a problem, add a filter to your exhaust fan. Alternatively, you can create a sealed, artificial environment using an air conditioner, dehumidifier, and additional CO2 system, but this can be quite expensive and is not recommended for beginners. Lastly, it’s a good idea to have a constant gentle breeze in your space, as it strengthens the stems of your plants and creates a less hospitable environment for mold and pests. For this purpose, a wall-mounted circulating fan (clip fan or similar) will work well.

Control and Monitoring

After choosing your lights and climate control equipment, you will want to automate their functions. Although sophisticated (and expensive) units are available to control lights, temperature, humidity, and CO2 levels, beginners will typically need a simple 24-hour timer for lights and possibly an adjustable thermostat switch for the exhaust fan.

Control the Light Cycle

The light-dark cycle is very important. Generally, you will have the lights on for 16 – 20 hours out of 24 hours while the plants are in the vegetative growth stage (18/6 or 20/4), and then switch (reduce) to 12 hours of light during the 24-hour cycle when you want them to flower (12/12). The light must be turned on and off at the same time each day, or else you risk stressing the plants, so a timer is essential.

You can also use the timer for your exhaust fan, but investing a bit more in a thermostat switch is a much better option. With basic models, you simply set the thermostat on the device to the maximum desired temperature for your space and connect your exhaust fan to it. Once the temperature rises to the set level, the fan will turn on until the temperature drops a few degrees below the set threshold. This saves energy and maintains a constant temperature.

Since you probably won’t spend most of your time in your growing space, a combined hygrometer/thermostat with memory function (high and low memory) can be very convenient for monitoring conditions in your space. A thermo-hygrometer, these small and inexpensive devices not only display the current temperature and humidity level but also record the highest and lowest readings since the last time you checked.

Monitor pH Levels

Additionally, it’s a good idea to have a pH meter or testing kit on hand to check the pH level of water, nutrient solutions, or soil. Cannabis prefers a pH between 6 and 7 in soil and between 5.5 and 6.5 in hydroponic media. If the pH goes outside this range, it can lead to nutrient lockout, meaning your plants won’t be able to absorb the necessary nutrients.

When growing in soil or substrate, it’s not necessary to adjust the pH of the water used for irrigation. Soil has a good pH buffering capacity, which means that even if the pH of your water isn’t ideal, the soil composition acts as a buffer and balances the pH of the incoming water to a generally acceptable level. However, for hydroponic cultivation, it’s essential to adjust the pH of the hydroponic nutrient solution as there’s no soil to act as a buffer and correct the pH level if it becomes unbalanced.

Growing Medium

When talking about growing medium there are 3 main types that are used:

• Soil (containers filled with soil/substrate) – most common, intuitive, excellent for bud aroma.
• Inert (soilless) – intuitive, faster than soil.
• Hydroponics – fastest, higher yields, and potential.

Each medium has its advantages and disadvantages. In this guide to growing cannabis, we will explain only the classic and simplest soil-based cultivation method.

Soil is the most traditional medium for indoor cannabis cultivation, and it is also the most forgiving, making it a good choice for first-time growers. Simply buy some quality potting mix and specially formulated soil nutrients to provide your plants with what they need until harvest. An excellent soil mix may contain ingredients like coconut coir, perlite, earthworm castings, bat guano, fish meal, crab meal, bone meal, blood meal, kelp meal, peat moss, humic acid, sandy loam, soybean meal, alfalfa meal, rock dust, mycorrhizae, etc.

Whichever substrate you choose, keep in mind that it is pre-fertilized (some more, some less). This means it already contains all the necessary nutrients for your plant’s initial growth. Therefore, for the first 2 – 4 weeks of growth, there is no need for additional fertilization, as excessive feeding can “burn” the plants. Monitor how the plants respond and only start fertilizing when they show the need for it. Start with half the recommended dose, and if the plants respond well, continue with the full dose.

Growing Container (Pot)

The type of container you use will depend on the medium, system, and plant size. For example, you can use 30-liter pots (8-gallon pots) for growing several large plants. Cheaper options include plastic containers, buckets, pots, etc., while some choose to invest more in so-called “smart pots,” containers designed to improve airflow to the root zone of the plant. Many growers start their first plants in 18-liter (5-gallon) containers. Drainage is crucial since cannabis plants are very sensitive to prolonged moisture in the root area. If using plastic containers, be sure to drill holes in the bottom to allow excess water to drain.

Watering

Water your plants when the substrate is completely dry. Water them less frequently but thoroughly, approximately every 3-4 days. In some areas, the water supply may contain high levels of chlorine, which can be harmful to beneficial soil microbes. For this reason, many growers let the water sit for about half an hour before watering to allow excess chlorine to evaporate.

The most important thing is not to overwater. Cannabis plants are very sensitive to root rot in overly wet conditions, and overwatering is one of the most common mistakes. The frequency of watering will depend on the medium, plant size, and ambient temperature.

Fertilizers / Nutrients

Growing quality cannabis requires more fertilizers or nutrients than most common crops. Your plant needs the following primary nutrients (commonly known as macronutrients):

• Nitrogen (N)
• Phosphorus (P)
• Potassium (K)

These micronutrients are also required but in much smaller quantities:

• Calcium (Ca)
• Magnesium (Mg)
• Iron (Fe)
• Copper (Cu)

It is recommended to plant your cannabis in a quality pre-fertilized substrate that has all the necessary nutrients for the initial growth (2 – 4 weeks). After a few weeks, the plant will deplete all the nutrients in the substrate, and you’ll need to start feeding it with an appropriate nutrient solution (every other watering).

If you don’t use pre-fertilized soil, you will need to feed the plants at least once a week using the right nutrient solution. These nutrients are sold in concentrated liquid or powder form that is mixed with water. Generally, there are separate formulas for vegetative growth and flowering. Most macronutrients are sold as two-part solutions to prevent the precipitation of certain elements that the plant cannot utilize (forming an inert solid). This means you need to buy one bottle of nutrients for the vegetative stage and another for the flowering stage.

However, there are various branded and specialized fertilizers, stimulators, additives, etc., for which you may need to spend more money, but as they say, “you get what you pay for.” Some quality fertilizers you can buy include BioBizz, Advanced Nutrients, Guanokalong, Hesi, Canna, Plagron, Mills Nutrients, etc.

Once you have the necessary nutrients, simply mix them with water according to the label instructions and water your plants. Always start with half the recommended dose, as cannabis plants are easily burned. The rule of thumb is “less is more,” and over time, you’ll learn to read the signs of deficiencies or excess.

Germination and Cloning

It is best to order feminized seeds from reputable websites. Once you have your seeds, it’s time to germinate them. To make the seeds sprout, they need to be placed in a warm and moist environment. There are many methods and techniques for germination. The simplest method is to plant the seeds directly into the substrate. You can also check the best 3 methods of germination here.

My personally preferred and most reliable way to germinate seeds is using a damp tissue or paper towel. Take a paper tissue from one of those classic packs of 10 pieces, and leave it folded as it is (don’t unfold it for a thicker layer). Place the seed inside the tissue and fold it again. Wet the tissue under a gentle stream of water, press it carefully, and drain off the excess water. Place another tissue around it, wet everything together again, and drain it off. Leave it somewhere warm (room temperature will be sufficient).

If you have multiple seeds, don’t place them all together in one tissue; instead, put each one separately. Check the tissue every 12 hours or so. If it’s almost dry, wet it a little more, but do not let it completely dry out. When the seed has sprouted a root, plant it as soon as possible in the pre-soaked substrate.

How To Germinate Old Seeds

Some seeds require longer than others to germinate, especially older seeds. The following method is particularly effective if, by any chance, you have older seeds that you have been storing for a long time (several years old). Place the seeds in a container or glass with lukewarm water (the container/glass should be transparent so you can see the sprout when it emerges) and let them soak overnight.

Warm soaking overnight will help soften older seeds. Most seeds will float, but after a few hours of soaking, they will sink to the bottom of the glass. However, if the seeds are left soaked for too long, they may drown. So, do not leave the seeds soaked in water for more than 24 – 32 hours. If after 24 hours, there are no sprouts, I recommend taking the seeds out of the water and moving them to a tissue (as described above).

Once you have planted your seeds in soil/substrate, you can maintain the necessary temperature by immediately placing the containers/pots under a light or on a heating plate. It should be warm but not too hot, around 25 – 30°C (77 – 86°F) is ideal. In about 2-4 days, you will see your seedling emerge.

Cloning

If you start with clones, treat them gently for the first few days. It is common for “cut” clones to be a bit relaxed or droopy; your job is to keep them healthy and happy. Keep them moist and under soft light (CFL), and spray them with water several times a day until they root. The light regimen for clones is 18/6, and the ideal temperature is 22 – 25°C (72 – 77°F).

Vegetation

The vegetative period is the growth phase when the plant becomes stronger and larger. The plant develops leaves and branches during this phase. The ideal temperature for vegetation is 20 – 30°C (68 – 86°F). During the vegetative phase, cannabis prefers a more humid environment, around 60% relative humidity.

In indoor cultivation, you can keep the plant in the vegetative phase as long as you provide it with at least 18 hours of light per day. You achieve this by connecting the light to a timer that will automatically turn it on and off as you set it. Light regimens for vegetation are 18/6 or 20/4, and some use 24/0, but it is not highly recommended as the plant still needs some rest (darkness).

Training

Cannabis is a very resilient plant, especially during vegetation, making it the best time for training your plants. Training is not mandatory, and you can have a harvest without training, but training your plants allows for a higher yield. Various training techniques allow you to control the plant’s growth.

The most popular training techniques are:

• Low-Stress Training (LST)
• Supercropping
• The screen of Green (ScrOG)

Damage/Pruning (Strategic)

• Topping
• Fimming
• Manifolding
• Defoliation

Manipulating Light Cycles

• 12/12 from seed
• Sea of Green (SoG)

LST (Low-Stress Training)

This technique allows growers to maximize their available space and light. It involves bending the plant’s stems and securing them in place, creating a flatter and wider shape. Use soft-coated wire to tie the stems after bending to avoid damaging the fragile stems. You can start training when the plant allows you to do so with its growth. Bend the stems before tying them to reduce the risk of breaking. LST is not a one-time thing; it’s an ongoing process as the plants grow.

SuperCropping

This is a more extreme bending technique, often used for tall and tough-to-bend stems. You soften the stem with your fingers, bend it at a right angle, and secure it because otherwise, the stem will soon straighten up.

The Screen of Green (SCORG)

The Screen of Green is a technique where growers use a screen over their plants and “push” the stems under the screen. The goal is to achieve a flat canopy with many well-distributed buds. The screen also serves as a support for heavy buds later on.

Topping and Fiming

Topping involves completely removing/cutting off the main tip of the plant, similar to taking clones. This stops its apical dominance or tendency to grow one main cola, and the plant will start growing by dividing into two main stems. Fiming is a similar technique to topping, but instead of completely removing the tip, you damage or “shave” it, resulting in potentially 3 – 4 main stems.

Flowering

The flowering phase starts when plants begin to form buds. To induce flowering, you need to change the light cycle to 12/12 (12 hours of light and 12 hours of darkness per day). When transitioning from the vegetative phase to the flowering stage, it is crucial to ensure that the plants receive 12 hours of uninterrupted darkness each day. Light leaks can be a significant issue during flowering.

If the plants do not receive consistent nightly periods, they may stop flowering and revert to vegetative growth or even turn hermaphroditic. During the flowering phase, plants become more sensitive to their environment compared to the vegetative phase. The recommended temperature during flowering is 18-26°C (65-80°F). Too much heat can cause the terpenes to burn, reducing the flavor and aroma of the buds.

There is evidence that high temperatures can also burn off potency. If possible, keep the humidity low as low humidity during flowering reduces the chances of mold while increasing trichome development. Many growers drastically reduce humidity in the last two weeks using a dehumidifier, which increases resin (THC) production and prepares the buds for drying while preventing mold.

Monitor the Humidity of Your Grow Space

During the last two weeks before harvest, you can lower the humidity by at least a bit. High humidity is above 60-70%, and some strains are particularly prone to mold in high humidity conditions. During the transition to flowering, plants undergo a stretch where they become taller and double in size. Some strains stretch less (Indica dominant), and some stretch more (Sativa dominant). If there were any issues with nutrition during the vegetative stage, the plant would continue to produce new leaves to replace the lost ones. However, towards the end of flowering, the plant will stop producing new leaves as it focuses on producing large buds.

If you encounter any problems at this stage, don’t worry too much. As long as your buds remain intact, and you have enough leaves, you will still produce high-quality buds. Buds that do not receive sufficient light will not grow, and lower buds or those in the middle of the plant with limited light and airflow will usually stay small. Therefore, during flowering, you should remove/trim the lower leaves and lower underdeveloped stems that don’t have sufficient access to light (Lollipopping).

In the last few weeks when the plant is close to harvest, it is normal for the leaves to start yellowing. Many growers “flush” their plants by giving them only plain water in the last few weeks before harvest.

Harvest

In the final weeks, the buds significantly thicken, adding much-needed weight to your final yields. You watch daily as the plant forms beautiful buds, and it might be tempting to harvest them as soon as possible. However, patience is essential, as a few weeks of growth can make a significant difference in the maturity of your buds. It’s crucial to wait until the right time for harvest.

The timing for harvest can be as early as 2 months of flowering, depending on the strain you are growing. Indica-dominant strains generally have a shorter flowering period compared to Sativa-dominant varieties, which can take up to 4 months to flower. Some growers stop giving nutrients during the last two weeks before harvest to allow the plant to flush out any excess nutrients or salts that may cause a chemical taste.

How to Harvest Cannabis On Time?

There are several techniques to determine the right time for harvest. One method involves observing the white hairs (pistils) growing from the buds. When they first appear, they are all white. As time passes, the pistils begin to curl and darken, turning yellow, red, brown, purple, or even pink, depending on the strain and growing conditions.

A general rule is to harvest when 50-75% of the hairs have changed color, but this is just a rough guideline as each strain is different. Some strains tend to remain mostly white even before harvest, so if it’s your first grow, it’s best to wait a few weeks longer than you might expect. There will be times when it seems like the buds are nearing completion, and suddenly a whole bunch of new white pistils will grow. Remember, harvesting too early will result in less potent buds.

While this method is not as precise as studying trichomes, it provides growers with a way to try to estimate when their buds are ready, especially if they don’t have access to a microscope or magnifier. Trichomes are the crystals you see accumulating on the buds and leaves. They contain most of the cannabinoids in your buds and change in appearance as harvest time approaches.

Use The Microscope

Under a microscope, trichomes look like small mushrooms. If the white “hairs” are mostly sticking out, and the trichomes are still transparent (clear), then your plant is too young and not ready for harvest. In that case, harvesting will result in a smaller yield. Harvesting begins when the plant stops producing new white “hairs,” and at least 40% of them have darkened and curled.

The highest level of THC is when most of the trichomes are milky white (cloudy). Milky trichomes have the highest THC levels, providing a more euphoric effect. Harvest can also be done a bit later when some trichomes turn yellow (amber). Yellow (amber) trichomes indicate a higher “body high” as some of the THC has converted into the less psychoactive CBN, which has calming and anti-anxiety effects. Some strains may even develop red or purple trichomes! When trichomes start to look gray or dried out, you’ve missed the ideal harvest time. You can also use a microscope to tell if your buds are mature enough to be harvested.

How to Use a Handheld Microscope

Instructions for using a handheld microscope: When using an illuminated microscope for the first time, my advice is to actually cut a smaller “head” from the plant for easier examination. You can try looking at trichomes on a living plant, but it’s generally awkward. If possible, place your “head” on something stable, like a table. Clean the microscope and press it on an area with trichomes.

Drying

There are several ways to dry the buds. You can hang the whole plant, but the drying process will be much faster if you cut the branches or individual buds and hang them to dry. Remove larger leaves, and for smaller leaves around the buds, just trim them.

You don’t necessarily have to throw away the trimmings; you can use them to make butter or something similar. Trimming smaller buds after drying can slow down the drying process. Ideally, you want the buds to dry slowly, so this could be a good technique if you live in a very dry climate. I recommend always trimming the buds before drying unless you have an urgent reason not to do so. Trimming becomes more difficult after they have dried.

Hang the Buds

Once you have cut and trimmed the buds, hang them upside down in a well-ventilated and dark place for drying. Essentially, you can hang the buds wherever you want, so be creative! You can also place them on mesh drying racks. This is a good choice for a humid environment. By removing the buds from the stems and placing them on a mesh rack, they will dry much faster than if hung upside down with the stem.

If you are not sure where to hang your buds, a closet works great, or your grow space (box) can also serve the purpose. A grow tent is an excellent place for drying, with controlled environmental conditions and plenty of space available. Many growers dry their buds in their closets or even in the living room. Make sure to spread your buds evenly without touching each other to avoid mold formation.

Check the Humidity

Very humid air or excessive humidity during the drying process is your enemy as it can cause mold. 60% humidity is optimal, although most of us are at the mercy of the drying conditions. With 60% humidity, it will take about 4-10 days for your buds to dry. At lower humidity levels, the drying will be much faster, so you need to closely monitor the buds and remove them before they overdry. Drying as slowly as possible without developing mold will give you the highest quality buds.

Curing

Curing involves slow-drying the buds to preserve and enhance their flavor and aroma. Technically, “curing” begins when the plant stops receiving water. From that point on, the plant starts to dry, and the curing process begins. Proper curing will eliminate the green/grassy smell of fresh buds and give you the excellent smell and taste you expect. It’s crucial to remove the buds from drying when they become crispy to the touch or when the stems start to snap instead of bending. Then, store the buds in airtight glass jars.

Most cannabis enthusiasts agree that the best smell and taste are achieved when buds are cured for a longer time. After sitting in the jars for several weeks, the buds tend to feel stronger and more potent! This may have to do with terpenoids. Terpenoids are compounds produced by cannabis plants that influence the flavor and aroma of the buds, and there’s some evidence they may also enhance potency or trigger other chemical processes. Whatever the reason, it’s evident that the curing process works. However, curing for more than 6 months doesn’t seem to have significant benefits. Curing for 1-3 months is more than sufficient to achieve the desired results.

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