Growing Cannabis - Part One

There are five stages in growing cannabis:
germination, seedling, vegetative growth, flowering, and harvest.

Germination Stage

When you look for information on germinating cannabis seeds, you will come across a variety of methods, some of which contradict the advice given in other methods. Here is my attempt at organizing the recommendations:

Step Options
Soak the seeds in water Options are to not soak the seeds in a glass of water but to put them directly into the growing medium, or to skip the soaking in water and go directly to the paper towel method below.
Type of water to use Some recommend only distilled water , other say you can use any water. Some recommend adding small amounts hydrogen peroxide to kill any fungus on the seeds. Some recommend adjusting the pH of the water to near neutral. One recommends adding sugar to the water.
Length of time to soak the seeds Generally soaking for no more than 24 hours in recommended, but other sources suggest a longer time. Some say just until the seeds sink because they can drown if they do not stay at the surface. Others say the seeds must sink.
Place the seeds on a paper towel that is damp but not dripping wet. Separate the seeds so the roots will not overlap when they start growing. One method says to use cheap paper towels because the tap roots can grow into the larger spaces on premium paper towels and get stuck there.
Fold the paper towel to cover the seeds I find that the paper towel can dry out easily and kill the seeds, so I prefer to put the seeds on part of the towel on the rim of the plate, then place a second paper towel in the center of the plate so it is next to the seeds but does not cover them. This can be used as a water source to wick moisture towards the seeds. Others fold the ends of the paper towel down to try to do the same thing.
Place the paper towel with the seeds on a plate Others prefer to put the paper towel in a sandwich bag and seal it with a bit of air in the bag.
Cover the plate with a second plate upside down to keep the seeds dark and decrease the moisture loss Other say to cover the seeds and plate with plastic wrap , while one seed dealer will not honour the germination guarantee if the seeds are covered at all.
Keep the seeds in the paper towel in a warm, dark place. Recommended temperatures vary widely but something in the 70 - 80 degrees F (21-27 degrees C) range should be safe. One source recommend temperatures up to 90 degrees F
Wait until the seeds have sprouted "tails" or tap roots that are 1-2 cm long, then carefully transfer them to either soil or a hydroponic soil mix, burying them only 1/4 inch below the surface. This is a consistent recommendation. Some suggest planting the seeds with the tap root down, and others say it doesn't matter if it is at an angle. Some recommend using a spray bottle to water the germinated seeds in the pots. One source suggests transferring autoflower seeds to their final pot to avoid loss loss of growth from later transplanting,

Most germination methods start with soaking the seed in water, usually for less than 24 hours. In this case, the water has been pH corrected to 6.5 and a trace of hydrogen peroxide has been added to clean the seed of any existing mold or fungus that may not be obvious to the eye.

My preferred method for germinating seeds is to place them on the rim of a plate, with the paper towel holding them set over a second paper towel that is in the middle of the plate. The seeds need both water and air. With this method extra water can be put on the thicker section in the middle of the plate. It is wicked up to the seeds, but they are still not soaked and have a good mixture of air and water.

How Much Space is Needed to Grow Four Cannabis Plants?

Soil Test
Before transitioning your sprouted seeds to any soil medium it is a good idea to check the soil using a soil test kit. This process involves mixing specified quantities of soil and distilled water, allowing the mixture to settle for a day, then taking the clearest water and testing it with the powder indicators supplied with the kit. This will give you not only the pH of the water, but information about the levels of the most important nutrients in the soil - nitrogen, phosphorus and potassium.
For seedlings, you want to keep the concentrations of nutrients at relatively low levels so the young plants don't suffer nutrient burn. This is most easliy accomplished by using a soil mix intended for seedings, rather than one of the potting or container mixes that are enriched with enough nutrients to feed the plant for 3 to 6 months.


What Type of Lights Should I Use?

In the beginning stages it is ok to use regular compact flourescent lights, either in the tube form or single fixture lamps. Grow lamp versions of these flourescent lights are even better, but the regular ones will work.

As the plants grow through the seeding stage, I generally switch over to LED grow lights. Over the past few years the price of LED fixtures has come down as the quality and power has gone up. Some units offer the ability to provide different colours of lighting to the plants as they go through different stages of growth. with more blue during the vegetative stage and more red as the plant goes through flowering. Whether you get a light with variable controls or one that has a fixed output, it is important to make sure it is "full spectrum" meaning that colours other than blue and red are included as well, though perhaps at lesser levels.

There are tools used by professional growers that can determine the amount of light energy the plants are receiving at different wavelengths, with an emphasis on the colours that are actually usable by the plants, but they are expensive, costing hundreds of dollars.

A rough estimate of whether a light falling on your plants is adequate or excessive can be obtained by using a light meter, which is usually calibrated in "lux".

For a detailed explanation as to how to do this, please see this video by Migro.

(Light meter)

Manufacturers often give high wattage ratings to their LED fixtures which are not borne out under more rigorous testing.

If you would like to understand the science behind lighting and how cannabis plants use the light, I consider this site to be one of the best -

and specific information on this topic is available on this page.


Seedling Stage

The seedling stage is generally considered to go from the time the plant puts out its first leaves (cotyledons) above the ground to until the stem has gone up about 4 or 5 nodes, nodes being the places on the stem where the branches are attached.

Seedling Stage

Seedlings are fragile, and they need the right conditions to thrive:

Temperature: Generally the 70 - 80°F range (20 - 27° C) will be a good choice.

Humidity: This can be regulated with the use of exhaust fans, humidifiers and/or dehumidifiers. It should be kept as close as possible to the level specified in a VPD chart like the one on this page.
For example, if the room temperature is about 75
degrees F, the chart will indicate that the relative humidity should be about 60%. If anything, seedlings need to have a little more moisture than plants at later stages of growth, but is it important not to let the humidity go too high (above 80%) or you may have issues with mold growing in the grow room or tent.

If your plants are in a enviroment that is drier than the recommended VPD, it would be important to mist them with pH corrected water using a sprayer, several times a day.

Combination thermometer/ hygrometer (humidity sensing) devices are not expensive and they really are a required item for any grow room or grow tent. Outside, of course, you have little control over these things so it is always best to start your seeds inside.

Water: The roots of the seedlings need both water and air. Take care not to overwater them by checking them regularly with a moisture meter. If the roots are too saturated by water, the plants will die. See below for more information about watering.

Nutrients: When the seeds first germinate they have all the food they need right inside the seed. As this is used up in the first few days, you will need to start giving the seedlings a very mild nutrient solution in their water if the nutrients are not being supplied by the soil. In hydroponics, there are stage specific nutrient mixes that can be followed according to the manufacturer's directions. If you are growing your seedlings in soil, be sure to use a soil that is specially made for seedlings. Regular potting soil is often enriched with nutrients that can actually be harmful to seedlings since the concentrations are too strong.

Light: Many growers recommend lower levels of lighting for seedlings, and the required distance from the seedlings to the light should be part of the information that comes with your grow light. There is no "average" for this since there are so many types of lights operating at very different wattages, with different levels of photosynthetically active radiation (PAR).

You can also learn to "read" the plant since it will give clear signals when there is too much or too little light.

When there is too much light, the plant will not stretch up adequately, and will stay close to the ground. You may also find the leaves curling inwards longitudinally as they try to reduce the amount of light they are getting by showing less surface.

When there is too little light, the plants will stretch up but the stems will be weak and they can fall over. Just move the lights closer and they should do better.

A Trick for No-Stress Transplanting of Seedlings

See the video.

A Word About Watering
Seedlings are very delicate, so it is best to keep them in the "Moist" range on your moisture meter at the beginning.

The problem is that, when you do this, the roots will remain fairly small because they do not need to travel far to get the moisture they want.

As the plants get ready to transition to the vegetative stage, and throughout that stage, it is a good idea to stress the roots a bit by letting the moisture level dip into the dry range for a few hours before watering. This causes the lateral roots to start reaching out further into the pot.

When using a moisture meter always be sure to take 3 or 4 readings at different location in the pot and at different depths. You may find different moisture levels in different areas because potting soil mixes different components which may hold on to water differently. Just take the average of all the readings before making a decision about watering.


The health of your cannabis plants above ground is reliant on the development of an extensive root system either in the soil or in the hydroponic solution. If you are growing your plants in soil it is important not to overwater them, and you should try to keep the water pH at a level that allows them to absorb nutrients well. This is generally in the pH range of 6.0 to 6.5 in soil or 5.5 to 6.0 in hydroponic solutions.

LED lights are a good investment since they generally provide more light for the amount of electricity consumed, compared to other types of lighting.

How I Set Up My Grow Room
(12:14) Aquarium Water is used to fertilze the cannabis.

How Not to Grow Cannabis Hydroponically


>>>> Go to Growing Cannabis Part 2 >>>>

Vegetative Stage

Plants grow extensively in the vegetative stage and the size depends on the specific type and strain of cannabis. Some of the small autoflowers may only grow a foot or two high, while sativas grown outdoors in large containers can actually reach heights of 10 feet or more!

This plant has four nodes on the stem, and it would be described as entering the vegetative stage. It is 17 days old.

During the vegetative stage, the requirements for temperature and humidity are similar to those in the seedling stage. The lights can be brought closer to the plants now that they are stronger, and it is a good idea to keep a fan moving air around to prevent mold or fungus growth, but do not aim the fan directly at the plants.

This is the stage when you need to start trimming your plants to give them an optimal shape and increase the number of stems that will produce "bud", which is the part of the plant most commonly used for smoking or the production of other cannabis products.

The natural shape of the cannabis plant is like a Christmas tree, with one large flower at the top, and smaller ones on the lower branches. Many growers prefer to stop the upward growth of the central stem by "topping" it, in order to get the plant to branch out wider and expose more of the stem ends to the light. This increases the overall yield of the plant.

Topping the apical bud of a plant to encourage more lateral growth.

Trimming can be done on the main growth stem only or on lateral branches as well. Personally, I find that a single topping will produce a plant with 8 nice stems reaching towards the light, and that is a good number of points for producing the colas, or buds which contain the medicine.

There are other methods growers use to maximize yields. One common issue is that the central stems tend to grow higher than the others, and closer to the light. Since the light needs to be adjusted to suit the nearest branches, this leads the lower branches to get less than optimal light. The solution used by many grower is to gently bend the highest stems down to the side, either with soft manipulation, or by tying strings with weights to them, or by tying them down to a frame of some kind.

Another type of trimming called "lollypopping" is also used very commonly, and it involves removing the leaves and buds from the lower 1/3 of the plant to encourage growth in the upper 2/3 parts. This also helps with air circulation, which is important to discouraging pests and mold growth.

Rapid Growth

Cannabis grows very quickly as it enters the vegetative stage. Here is a picture of a plant that is 31 days old, next to a seedling that is 4 days old.

Water pH
There are a number of different types of tests for water pH, but I think the easiest one to use is the digital meter shown in the pictures below. Generally, cannabis prefers water on the slightly acidic side at about pH 6.5. Those who get involved in hydroponics will want to set the pH level even lower than this, generally in the range of 5.5 to 6.0. The reason why water pH is so important is that the nutrients required by the plant are only soluble, and usable by the plants, at certain pH levels.

Another factor is that, if you have done a soil test and you find, for example, that your soil is too acidic, you can either balance the soil be amending it with a supplement (preferred) or you can influence the pH of the soil by supplying water that raises or lowers the pH.

Testing with the pH meter, and adding adjustment solutions (pH up or pH down) is a relatively straightforward process. Be conservative in the amounts you add. Less than 1 ml of the pH down solution can quickly change the overall pH of water in a 2 litre container.

If you plan to grow your cannabis hydroponically, you will also want to make measurements of the level of nutrients you are putting into the solution. This is important not only as you prepare the initial solution, but also as growth proceeds because the plants will be absorbing nutrients, which will need to be replaced to maintain optimal growth.

What are pH, EC, TDS and PPM and How Are They Connected?

Looking for More Detailed Information?

Be sure to check out Coco for Cannabis' section on articles and tutorials.

Recommended Video:

Backyard Cannabis Growing Tips

>>>> Go to Growing Cannabis Part 2 >>>>


HELP! There is something wrong with my plants.

Plant Doctor - Diagnose Your Plants

A guide, with pictures of common cannabis nutrient problems is available here.

Often the leaves of the plant will tell you what is wrong. In this case, the necrotic spots on the lower leaves of this seedling suggest there is a potassium deficiency. Brown spots on leaves can also occur if there is not enough calcium.

Advice Regarding Pests


Marijuana Pests and Bugs - Control and Identification

Pests, Bugs and Viruses

The Three Most Common Cannabis Pests & How To Get Rid of Them


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