Updated: Feb 7
Cannabis is a flowering plant that is grown for its flavonoids, psychoactive cannabinoids (THC) and terpenes that have both physical and psychological effects on the body. There are two main Cannabis types, Cannabis sativa and Cannabis indica. Cannabis sativa is native to Southeast Asia, Central America and South America where the plants grow to be very tall and skinny. Cannabis indica is native to the middle eastern countries of Afghanistan, Pakistan and Tibet. These plants grow to be much shorter and bushier than Cannabis sativa.
There are thousands of cannabis strains available for purchase with more being developed regularly by crossing different strains to make hybrids. Strains are hybridized by fertilizing a male variety of one strain with a female variety of another strain. Here are some of the most popular hybrid strains available today:
Sour Diesel (Sativa)
Jack Herer (Sativa)
Blue Dream (Sativa)
Bruce Banner (Sativa)
Hindu Kush (Indica)
Girl Scout Cookies (Indica)
Northern Lights (Indica)
Wedding Cake (Indica)
Cannabis is a dioecious flowering plant that produces male and female reproductive organs on separate plants. Male plants are undesirable because they do not produce flowers. These plants produce pollen sacs that fertilize the female plant’s flowers. Once the flowers on the female plant have been pollinated, the plant will stop flowering and begin producing seeds. Therefore, male plants should be discarded as soon as their sex has been determined to prevent them from pollinating the female flowers.
To determine if your plant is male or female, look for the reproductive organs. Male plants develop very apparent pollen sacs and female plants produce flower buds. The first sign of a flower bud on a female plant are the stigmas which look like white hairs coming from a bud at the crotch of a stem.
The downfall of not knowing if your seeds have been feminized is that the only way to know the sex of your plants is when they begin to develop their reproductive organs. This can be a time consuming and costly process.
Unlike clones, cannabis grown from seed can vary in their genetics. Each seed carries 50% of the genes from the female plant and 50% of the genes from the male plant.
Cannabis plants stay in their seedling growth phase for about 2-3 weeks until they are able to grow strong enough to produce full leaves. Once the plant has grown at least one set of full grown leaves, it is in its vegetative growth phase until it flowers. The vegetative growth phase is the prime time to get the plant full and healthy before it flowers. This is also the best time to begin pruning so you have a bushier plant with multiple stems to grow flower buds on. The more stems the plant has, the more potential there is for higher flower yields. The pruning process while the plant is in its vegetative growth phase is pretty simple. Cut back each stem while the plant is young to encourage bushier growth. Multiple stems will grow from the cut point opposed to just one, long stem.
Cannabis plants that become stressed can turn into hermaphrodites, developing both male and female sex organs on one plant. These plants should be discarded because the pollen will fertilize the flower buds and cause them to produce seeds instead of large flower buds.
Growing Cannabis from clones
Taking clones is a quick way to start cannabis plants because it eliminates the seed germination and seedling growth stage time frame. Clones are cuttings taken directly from a mother plant and will have the same genetic makeup as that plant. Mother plants are chosen for the desirable traits of specific strains. They are kept in a vegetative growth stage to be able to provide an unlimited supply of clones for continuous crops. The mother plants are able to stay in a vegetative growth stage by keeping light on them 18+ hours a day. Any period of darkness or reduction in the amount of light hours they receive will move them into a flowering stage and they will no longer be able to be used as plant stock.
An added advantage to growing cannabis from clones is that the sex of the plant is known to be female. Unless the seeds you are using are verified to be feminized seeds from a breeder, there is a possibility that some are males. Growing cannabis plants from seed only to find out they are male is a costly attempt.
Tools You Will Need to Grow Clones
How to Clone a Cannabis Plant
Step 1: Choose a thick stem with no sign of disease. The stronger the stem and leaf growth, the stronger the clone will be.
Step 2: Make the cut right below any node and about 6” down the stem at a 45° angle. Cutting at an angle allows for more surface space for roots to grow.
Step 3: Trim off the lowest leaves on the cutting, leaving only 1-2 leaf sets at the top. Leaving the bottom leaves on the stem can cause rotting if they rest in water or on moist soil.
Step 4: Dip the tip of the cutting at the node in a rooting hormone such as Clonex.
Step 5: Immediately place the cutting in a soilless planting medium such as perlite, coco coir, rock wool cubes or an aeroponic system. Cuttings not immediately given moisture will quickly wilt and begin to die, degrading the health of the cutting.
Step 6: Regularly mist the leaves to boost moisture.
Growing Cannabis from seed
When growing cannabis from seeds, it is best to germinate more seeds than you intend on keeping. Not all seeds will germinate and some might be males if not feminized from a breeder. Seeds do not need high quality soils to germinate. Any type of soil medium such as peat moss, coco coir or perlite will work as long as you are keeping the medium moist at all times until the seeds germinate. General potting soil can be used, but the high organic matter in potting soils can cause bacteria and fungal growth which can be detrimental to young seedlings if too much moisture builds up.
Seeds should be started indoors in a warm environment. Seeds need temperatures to be at least 60° F to germinate properly. Temperatures below 60° F can cause a fungal disease called ‘damping off’ from an excess amount of soil moisture combined with low temperatures. Signs of damping off are very thin stems that eventually rot and collapse. Warming mats can be used to increase warmth. With proper moisture and warmth, germination can take about 3-10 days.
Auto-flowering seeds are a type of seed that have been bred with genetics causing them to grow rapidly that allow the plant to be grown from seed to harvest in three months. The flowering growth phase on these plants is automatic and not determined by the amount of sunlight they get. These plants are smaller in size and have lower yields, but multiple crops can be grown in a year because of how fast their life cycle is.
Tools You Will Need to Germinate Seeds
An alternative is to buy a seed starting mix and fill any type of container
How to Grow Cannabis from Seed
Step 1: Fill a germination tray with the soil medium and give it a good soaking so it becomes absorbent.
Step 2: Place the germination tray on a warming mat.
Step 3: Bury the seeds ¼-½” deep and 1” apart or one seed per cell depending on the type of germination tray and cover with the soil medium.
Step 4: Water the soil again to ensure it tightly forms around the seeds.
Step 5: Mist the soil with a spray bottle when the soil begins to dry. Avoid heavy, overhead watering to reduce the chances of disrupting the seeds.
Step 6: As soon as the seeds germinate and there is growth above the soil line, place a grow light over the seedlings for at least 18hrs a day.
Step 7: Pinch off multiple seedlings that have germinated in the same cell leaving only one so they don’t compete with each other for resources. Pinching off the seedlings instead of pulling them out will prevent the disruption of the kept seedlings roots.
Step 8: Transplant the seedlings to larger pots or in the ground when they have at least two sets of leaves.
Growing Cannabis indoors
Growing cannabis indoors is highly beneficial because anyone that lacks outdoor space can do it. Growers have the ability to get more creative with indoor grow space by utilizing a smaller space. Crops can either be grown in soil, hydroponically or aeroponically indoors. A huge benefit of growing cannabis indoors is that crops can be grown any time of year, regardless of the season because all variables such as lighting, temperature, humidity, water and nutrients can be controlled.
Cannabis plants grown indoors should be under at least 18 hours of light a day until they are big and strong enough to bear flowers. More hours of light is needed for indoor plants because artificial lighting is not as strong as natural sunlight. The vegetative growth stage time frame can be anywhere from two to eight weeks and the flowering time frame ten to sixteen weeks depending on the cultivar. Once you want your plants to begin flowering, reduce the lighting to twelve hours a day until harvest. If there is any chance of light interference during the twelve hours of needed dark hours to promote flowering, blackout materials such as grow tents can be utilized.
Since indoor spaces must be manipulated to be healthy growing environments for plants, equipment such as fans and dehumidifiers should be installed. The more plants you grow in an indoor space, the more humid the air will become. If humidity levels are above 50% and there is not enough air flow, fungal spores can accumulate and infect your plants. The air temperature should be between 68° F and 85° F. Temperatures out of this range can put stress on the plants, inhibiting flowering. Humidity levels and temperature can be measured using a hydrometer.
Unless you are growing your plants hydroponically, highly nutritious soil should be used. The soil you use can be premixed or you can make your own recipe as many experienced growers do. Foxfarm company has a large variety of high quality soils and soil conditioners.
Air Cooled Reflector Hood
Fans (Size & quantity is dependent on grow space)
Dehumidifier (Size & quantity is dependent on grow space)
Ability to manipulate all growing conditions.
Can grow any time of year, regardless of the season.
Minimal environmental pollutants.
Can be expensive due to startup costs on equipment and utilities.
Bacteria and fungal diseases can easily spread if there is a lack of air flow or the humidity is too high.
The plants emit odors, especially when flowering.
Growing Cannabis outdoors
Growing cannabis outdoors is great if you have the space and nutrient rich soil. You will need to ensure that your outdoor space is secure from other people and pollutants. Cannabis plants grown outdoors need at least six hours of sunlight a day for healthy growth.
To get a jump start on the season, seeds can be germinated indoors and transplanted outdoors once the seedlings have developed at least two sets of true leaves.
Plants should be put in the ground by the summer solstice on June 21st when there are the most sunlight hours in a day and the least amount of dark hours. The plants will begin to flower in the fall when the amount of sunlight hours decrease and night time hours increase. Outdoor lighting can be manipulated as done in indoor grows but requires light deprivation material.
When growing outdoors, it is important to test the soil quality, especially if it is not known what the property was used for prior. Soil tests can be sent to local labs to test for various things such as pollutants, nutrients and pH. Contact your local extension office for resources on where to test your soil. If your soil is not nutritious and the structure is clay-like or sandy-like, it must be amended with more nutritious and porous soil before planting. A mixture of the native soil, compost and manure will liven up the soil.
Plants should be spaced at least three feet apart for proper airflow and for more maneuverability between the plants. Install support posts or trellising to ensure your plants do not bend over, especially for sativa cultivars that can grow to be very large. Install a support system for your plants before planting to reduce potential damage to the plants.
When planting the cannabis plants into the ground, remove some of the bottom leaves and bury the stems deeply. Roots can grow down the entire length of a cannabis plant’s main stem. The more stem that is buried, the stronger the plant will be. This is especially important for plants grown outdoors to stabilize them during heavy winds.
Tools You Will Need
Low startup and maintenance costs.
Artificial lighting doesn’t compare to natural sunlight.
There is no need to constantly regulate temperature, humidity and lighting.
There are no constraints on how big the plants can get.
Environmental pollutants can stick to the plants.
Seasonal or environmental factors put restraints on when to plant or harvest.
The soil must be amended if it lacks structure and nutrients.
Too high or low temperatures can put stress on or kill the plants.
There is an increased presence of insects and other pests.
There is a risk of theft or complaints.
Growing Cannabis hydroponically
Growing cannabis hydroponically is the preferred method for many growers because of how much more quickly the plants grow. Cannabis plants grown hydroponically grow faster because they are able to take up nutrients more quickly when they are dissolved in water opposed to soil. Many growers also prefer to grow their plants hydroponically because of how much control they have over variables such as nutrient levels, pH and electrical conductivity (EC).
Regularly monitoring the water pH and EC with pH and EC meters is a necessary part of growing cannabis hydroponically. If pH levels are too high (alkaline) or low (acidic), the plants won't be able to absorb nutrients through their roots properly. pH levels should be between 5.6 - 5.8.
EC is the electrical charge from fertilizer salts in water. The higher the amount of salts in the water, the higher the EC will be. If EC levels are too low, the plants can become deficient in nutrients. If the EC is too high, the plants can get damaged from salt toxicity. EC levels will fluctuate depending on the plant’s growth stage because of the different nutrient levels the plant needs at different stages. The EC levels at the vegetative stage should be 1.0 to 2.0 and 1.5 to 2.5 in the flowering stage. Slowly increasing the fertilizer throughout the growth stages will reduce the chances of over-fertilizing your plants. Over-fertilized plants will have burnt leaves, stunted growth and damaged roots. If the EC is too high, leach out the nutrients by adding clean water. If the EC is too low, slowly increase the fertilizer levels.
Growing cannabis hydroponically is commonly done indoors so environmental factors such as temperature and humidity can be better controlled. Humidity should be 50% or less and the temperature should be between 68° F and 85° F. Humidity levels and temperature can be measured using a hydrometer.
The roots of cannabis plants grown hydroponically need oxygen in order to survive. A lack of oxygen in the water will cause the roots to drown and rot. Adding oxygen to the water can be done by placing air stones in the water which are attached to an air pump with tubing. The air pump pumps air through the tubing and through the porous air stones, creating oxygen bubbles in the water. The air pumps should run continuously through all growth stages.
There are many different hydroponic growth techniques, depending on the grower’s preference. Some of these techniques include aeroponics, nutrient film technique (NFT), Ebb & Flow and deep water culture.
Aeroponics - The plants are suspended in the air and the roots are continuously misted with a nutrient/water solution. Air stones are not needed.
NFT - A nutrient/water mixture continuously flows through the plant’s roots using gravity. The nutrient/water mixture is recycled using a pump.
Ebb & Flow - The plant’s roots are submerged in a nutrient/water solution for 5-15 minutes every few hours. The solution is recycled after being drained into a reservoir and pumped back to the plant’s roots.
Deep Water Culture - The plant’s are planted into a soil medium of either clay balls or rock wool contained in a mesh pot that is submerged in a bucket of a nutrient/water solution.
Tools You Will Need
Air stones or air hoses
Grow medium (coco coir, perlite, rock wool cubes, clay pebbles, vermiculite)
pH and EC meters
The plants grow significantly faster.
A lack of soil makes it a cleaner option.
Environmental parameters can be controlled.
Lower water usage.
It takes up less space.
There is an ability to manipulate all growing conditions.
Plants can be grown any time of year, regardless of the season.
There are minimal environmental pollutants.
The grower needs to know the technicality of pH, EC & nutrients.
There is little room for correction if mistakes are made.
The equipment can be expensive.
High electricity costs.
Whether you are growing your Cannabis plants indoors or outdoors, nutrients are imperative to vegetative growth and flowering. Cannabis plants are heavy nutrient feeders due to their size and flower yields. These plants can easily become deficient in nutrients if not fed regularly throughout the growing season.
Nutrient deficiencies often show up right away with signs of deficiency in the leaves, especially when the plants are in the flowering stage and feeding on nutrients the most. Knowing how to spot nutrient deficiencies is imperative to correcting further deficiencies.
Common nutrient deficiencies in cannabis and their symptoms:
Nitrogen - leaves turn yellow starting with the older leaves and moving upwards, stunted growth, stunted growth, premature flowering.
Phosphorus - lower leaves turn an abnormally dark green/copper/purple color, lower leaves develop necrotic spots, petioles turn purple in color, stunted growth.
Potassium - leaves turn yellow starting with the older leaves and moving upwards, leaf margins turn a rusty color, reduced flowering, weak stems.
Magnesium - Interveinal chlorosis on lower leaves, rust color lesions appear on lower and middle leaves, older leaves curl and drop.
Calcium - Lower leaves curl, yellow-brown spots on leaf margins, stunted flower development.
The three main nutrients that Cannabis plants feed on the most are nitrogen, phosphorus and potassium. Nitrogen encourages large foliar growth such as leaves and stems, phosphorus strengthens foliar growth and flowering and potassium strengthens plant tissues and root development. Along with these three main nutrients, Cannabis needs smaller amounts of Calcium, Magnesium, Iron, Boron, Copper, Manganese, Molybdenum, Sulfur and Zinc.
All of these nutrients are found in high quality soils and all purpose fertilizers, but can quickly become depleted by the plants or other environmental factors. Using high quality soil and fertilizing regularly will help your plants stay healthy through all growth cycles and reduce the chances of disease. All purpose fertilizers with equal amounts of all needed nutrients can be fed to your plants regularly or many growers choose to use a high nitrogen fertilizer through the vegetative growth stage and switch to a high phosphorus fertilizer when the plants begin to flower. Products like FoxFarm Liquid Nutrient Trio make adjusting nutrients based on the growth stages easy. Other natural soil amendments for added nutrients include:
Blood meal or fish meal for nitrogen
Earthworm castings for nitrogen
Bone meal or bat guano for phosphorus
Wood ash or kelp for potassium
Dolomite lime for calcium & magnesium
Epsom salts for magnesium and sulfur
It is important to know when your cannabis flowers are ready to be harvested for optimal THC levels and flavor. Flower buds are ready to be harvested when the stigmas turn from white to amber in color and the trichomes turn from clear to amber in color. The average timeframe for harvest is seven to nine weeks after flowering begins and at fall equinox if growing by the moon cycle outdoors. You may need a magnifying glass to determine when the trichomes turn in color. Waiting too long after the stigmas and trichomes have turned amber in color will result in a loss of THC. THC levels begin to decrease after the flowers mature.
Allowing your cannabis plants to dry is an imperative step in the harvesting process. Not allowing your plants to dry before trimming and storing can cause them to mold when stored. Temperature and humidity factors will determine how quickly the plants will dry in order to harvest the flower buds. Harvested plants left to dry in sunny, hot conditions with low humidity can cause the cannabinoids and terpenes to degrade. Air flow and thermometer and humidity gauges should be monitored regularly to ensure the drying environment is ideal.
Tools You Will Need
Step 1: Cut each plant down at the base of the main stem where it meets the soil.
Step 2: Hang each plant upside down or lay them on a mesh drying rack in a shaded environment between 60-70°F with humidity levels between 55-65%.
Step 3: Trim off the fan leaves. These are the large leaves that will not have any crystals on them. Leaving them on the plants will prevent the plants from drying out properly as these leaves hold onto a large amount of moisture.
Step 3: The flower buds should be ready to be trimmed off the stems when you are able to easily snap the stems in half. This means enough moisture has evaporated from the plant. This can take anywhere from 2 to 7 days, depending on environmental conditions.
Step 4: Using pruners, cut each flower bud from the main stems. Minimal amounts of stems should be left on the flower bud to reduce the moisture content large stems contain.
Step 5: Store flower buds in an airtight container to cure and preserve the quality of the flower buds.
Step 6: After 4-6 weeks the flower buds should be ready for consumption.
The most common pests of Cannabis are insects such as spider mites, aphids, thrips and fungus gnats. These insects do not have cannabinoid receptors like mammals do, so the psychoactive properties that cannabinoids have on us, do not deter insects from feeding on the plants.
It is important to control insects at the first sign of them to reduce the chances of an infestation. Insect infestations can occur on both indoor and outdoor grow operations, but are most prevalent in outdoor grows. It is recommended to treat insects with organic products, especially if you are going to be consuming cannabis flowers.
Signs of an insect infestation are small, white or brown holes in the leaves, a sticky excretion on the leaves and webbing. Insects often hide on the bottom of the leaves, so it is important to treat all parts of the plant, including the bottom of the leaves when treating the plant.
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Insecticidal Soap https://a.co/d/47sDzpi
Releasing predatory insects such as ladybugs, predatory mites, lacewings
The most common diseases of Cannabis are fungal diseases such as rust and powdery mildew or tomato mosaic virus. Fungal diseases often develop when there is high humidity and/or a lack of airflow.
Fungal infections can be treated with Horticultural Oil https://amzn.to/3uafo2k.
The Tomato Mosaic Virus has no cure and the infected plant parts should be discarded.
If you have any more questions about how to grow Cannabis, we will be happy to assist you in a virtual telehealth appointment with one of our Plant Specialists. Please click on one of the options below to book an appointment.