Professional Marijuana Grower


Successful Cannabis Plant Propagation

Posted September 22nd, 2017 by Dustin Fraser in

A successful high-performance outdoor cannabis garden that delivers impressive yields from healthy plants begins on the day the first roots sprout. Cannabis plant propagation can be done one of two ways. The first way is by starting brand new plants from seed. The second is through the rooting of cuttings taken from a donor plant called a “mother,” a process of asexual plant reproduction which is commonly referred to as “cloning”. Both methods are reliable avenues to take when starting and each one has its own benefits.

Considerable care and attention is required throughout the early propagation period since even the smallest mistake or miscalculation can cause unwanted stress on the young plants. When plants experience stressful situations at an early stage of development, growth rates will usually be reduced. Small mistakes can lead to several undesirable results such as plants that mature too early in the season, plants that mature too late in the season, or plants that are highly underdeveloped. By creating and maintaining the ideal environment and situation throughout the early propagation and plant development stages, a grower will be able to ensure their crop will be healthy with high yields.

Seed Propagation

Starting cannabis plants from a reliable seed source is the best way to ensure that the young plant, or seedling, will be pure with regard to the intended genetic makeup of the plant. The advantage of seed propagation over cloning is that propagation limits the chance of predisposition to potential problems a clone plant may inherit from the mother plant. A grower starting straight from seed can be confident that the plants he or she is growing will have greater genetic diversity and possibly be more productive.

The most important aspect of starting plants in this manner is the source of the seeds. Inferior seeds will lead to inferior plants and yields. If, as a grower, you do not breed your own seeds, then you must be sure to purchase them from the most reliable and respected source available. Seeds from the most respected local sources are always recommended. Buying local is important for good reasons. Seeds that were produced in the same region where the grower lives will come from plants that were bred in that same environment. The resulting seeds will give life to plants that are more genetically adapted to cultivation in the same regional area. Seeds from respected local sources also tend to be fresher or newer which will increase the rate of germination (sprouting) when planting time comes.

If they are available locally, seeds that were saved from the previous year’s crop are definitely preferred. Try to avoid seeds that are over two years old because the older the seeds, the less reliable they will be. Seeds from foreign sources or from overseas tend to be older and germination rates can be inconsistent, so stick with local well-known seed sources and start the garden off on the right foot.

For seeds to sprout properly they need favorable conditions. The factors that account for such conditions are moisture, temperature and sometimes light. Cannabis seeds are no exception and will sprout best in warmer, more humid conditions. Starting the seeds indoors in March will ensure that the plants are far enough along in development and size to be planted outdoors come May. To give the seeds a little jump start and to help decrease the time it takes to sprout (the germination period), soak the seeds for 24-48 hours in a solution of sea kelp and water. Sea kelp contains, among other things, naturally occurring plant growth hormones that can help trigger germination of the seed. The plant growth hormone that this reaction is mostly attributed to is the growth hormone called “auxins”.

A normal, untreated cannabis seed could take seven to 10 days to germinate and sprout its first root, called the “radical”. Cannabis seeds soaked in a solution of about one part sea kelp to 100 parts water will begin to sprout their initial radical root in around one or two days. Both concentrated liquid and water soluble powdered sea kelp extracts will work effectively to increase germination rates and times.

Once the seed coat, or shell, has split open and the first root is beginning to emerge, the seed should be sown into a peat seed-starting pellet. Other starting mediums, such as rockwool and potting mix, will work for this step but peat pellets are preferred. They have the ability to hold relatively high amounts of both water and oxygen when they expand, while still maintaining excellent drainage, preventing them from becoming waterlogged.  Soak the peat starter-pellets in a warm solution of sea kelp and water that is pH adjusted to around 6.O, a pH level that most plants respond to favorably. Many of the products available for lowering the pH of a solution contain either sulfuric or phosphoric acid. These acids are quite corrosive and can be potentially more dangerous for a grower to handle. If a grower is looking for a less corrosive alternative, a 99 percent citric acid water soluble granular product is an excellent alternative. It is available in multiple sizes and can even be purchased in bulk 50-pound bags. It can also be used to make citric acid stock solutions of various concentrations or mixed into water and nutrient solutions at very small amounts to help lower pH.

Let the peat-starter pellets soak just long enough to completely absorb the solution and then place the sprouted seed about a ¼-inch deep into the center of the pellet. Throughout the entire seedling and early development stage the plants should be watered when needed with the same type of pH-adjusted sea kelp and water solution as described above for the peat starter pellets. Make sure to use warm water and apply the solution to the plants immediately after mixing. The roots prefer warm water and will grow much more rapidly than when given cold water.

Cannabis seeds need constant warmth to germinate, but they do not require light. However, once the plants begin to produce their first sets of “true leaves” they will require an adequate light source to perform photosynthesis. Photosynthesis is the exchanging of gases, oxygen for carbon dioxide, from the surrounding atmosphere and is an important process in plant growth. The peat starter-pellets with the sprouted seeds planted in them should be placed in a standard 10″ x 20″ starter tray, with drainage holes. This is a good way to make sure your plants don’t stay too wet after a watering and will not sit in water that may become stagnant and low in dissolved oxygen. Roots require high levels of dissolved oxygen from fresh water and sitting too long in water or in a solution can cause the roots to die. The peat starter-pellets will provide some air pruning of the roots on their own. This natural air pruning will lead to more abundant new roots.

Next, place a short, two- to three-inch tall humidity dome on top of the tray to help retain moisture and heat within. Mount a four-bulb t5 or t8 fluorescent grow-light fixture with 65K-rated bulbs just above the top of the humidity dome. Keep the lights on for 18 hours each day. Make sure the fixture height is easily adjustable and can be raised when the plants need water or as they grow taller. The fluorescent lights should provide enough heat to encourage rapid growth. Ideal temperatures will be 70-80 degrees Fahrenheit within the dome with a relative humidity between 60-70 percent when sprouting the seeds. If temperatures are too low, then an electric heat mat can be placed underneath the tray.

During the next few weeks, after the tiny plants have completely emerged from the seeds, the seedlings will begin developing several sets of “true leaves”. The first sets of leaves that appear are called the cotyledons and will look different than the normal leaves. The sets of leaves that come after those and look like normal leaves are referred to as the “true leaves”. During the first weeks that the true leaves are developing, the humidity dome should be removed for a few hours a day. Add more hours each day until the plants are acclimated to the environment and the dome can be permanently removed. Seeds love high humidity, but seedlings do not because it interrupts two important life-sustaining processes called transpiration and respiration. After the plants, roots and top growth begin to get crowded it is time to transplant them into a larger container. They should then be removed from the greenhouse, or greenhouse style structure. Make sure the temperature will remain above 60 degrees Fahrenheit at night.


Starting from rooted cuttings or clones is the best way to ensure the starter plants will be female in sex and true to the intended strain. In general, clones won’t grow as large as plants started from seed, but they can be high-yielding crops when grown properly. Clones cut from a young, fresh donor plant, or “mother” plant, are best. Mother plants to be used as a source of clones for next season should be started from seed in mid-autumn when things in the outdoor garden are winding down. Fresh mothers are recommended because as the plants age the genetics of the clones can begin to degrade and they may even become hermaphrodite or male. Allow the mother plants to become bushy and in early March harvest the clones from the lateral shoots that develop between the stems and the lower branches by cutting them at a 45-degree angle at their base. Clones should be taken from female plants. If a grower does not have the availability to maintain mother plants, then clones should be obtained from locally respected sources. Make sure to verify quality genetics. Also, be sure your clones are free of bugs, pests, and mold before introducing them into your garden.

Immediately after cutting the clone from its mother plant, dip the cut end into a powdered (or liquid) nitrogen-fixing bacteria supplement (Azospirillum brasilense) and place it in high-quality rockwool starter cubes that have been soaked in warm water adjusted to a pH of 6.0. Use 99-percent citric acid to lower the pH of the water just like it is stated in the seed propagation section. Some growers use cloning gels containing synthetic rooting hormones, but that is not really needed when rooting cannabis clones. Rooting hormones are more important when the grower is rooting cuttings of plants, like roses, which have a harder external tissue that does not easily develop roots. As long as the rockwool stays warm and kept moist with pH adjusted water (pH 6.0) the roots will usually pop out on their own. The nitrogen-fixing bacteria just give them a little boost. House the rockwool-clad clones in a standard 10″ x 20″ starting tray indoors under a four-bulb t5 or t8 fluorescent grow light fixture with 65 K-rated bulbs just like it was explained for seed propagation. Place a six-inch humidity dome-lid on top to trap the humidity, and set the light fixture just above the dome making sure it is height adjustable so the humidity dome can be easily removed for watering.

Keep the rockwool cubes continuously moist with the pH-adjusted warm water and remove excess water that accumulates in the bottom of the tray. The temperature inside the dome should stay between 70-80 degrees Fahrenheit and the lights by themselves should produce enough heat to maintain this temperature. If it does not, then the addition of a heat pad underneath the tray can be used. At times the clones may appear droopy, but don’t worry because this is natural before they develop their roots. In about one to two weeks, roots should begin to emerge from the rockwool. At that time the dome should be removed daily for one- to two-hours to help the clones acclimate to life outside the dome. Remove the dome for longer intervals as more roots begin to form, eventually removing the dome completely. Once the clones are fully rooted and the top growth is perky again it is time to transplant them into a larger container. Unlike the plants started from seeds, the cloned plants can stay inside under artificial lighting, preferably fluorescents, until they will be brought out to the greenhouse in May.

Transplanting & Housing Starter Plants

Plants grown utilizing the high-performance method will be transplanted twice in their lifetime. First when they are small seedlings or rooted clones, and then again when they are placed into their final outdoor home once the conditions are appropriate. Transplanting is done the same way for both seedlings and rooted clones. The key to a high-performance outdoor cannabis garden is in the rapid development of an extensive root system. An expansive root system leads to an increased ability to absorb larger amounts of water and nutrients. The more nutrients a plant can access the bigger it can grow. For that reason every container used should be a fabric aeration container. The initial transplant from the seedling/clone stage should be into a five- to 15-gallon size. A five-gallon container is the absolute smallest a grower should use.

Fill the containers with a soil-less potting mix that has a low-to-moderate nutrient charge, but is similar to what will be used in the final outdoor containers. A mix that is mostly comprised of inert materials, such as peat moss, perlite, or vermiculite, will have a lower nutrient charge when compared to mixes that contain organic materials like earthworm castings, kelp meal, or composts to name a few. The soil-less potting mix can be pre-moistened if desired to create a uniform distribution of water. When transplanting, it is important to not overwater as doing so will slow down the initial root growth, lengthening the amount of time it takes for the plant to recover from the transplant stress and to assimilate to the new container. High-performance outdoor cannabis gardens thrive when growth and development is not interrupted, even for a short time.

To help reduce the stress of being transplanted to a new container the seedlings or clones should be treated with beneficial microorganisms or microbes. The two main microbes that will help the plant recover quickly are the nitrogen-fixing bacteria Azospirillum brasilense and the Arbuscular Mycorrhizae fungi Glomus intaradices. Azospirillum breasilense is a beneficial bacteria that attaches to a growing root, forming small nodules, and that helps convert nitrogen from the atmosphere into plant available forms. Mycorrizae fungi, on the other hand, have the ability to locate and obtain nutrients in the soil mix that may be less available to the roots. The nutrients can become unavailable to the roots for many reasons. They may be in a portion of the growing media that the roots have not or cannot access for some reason, or they might have become attached or bonded at the ionic level to an opposite charged soil particle, which is often the case for positively charged phosphorus ions. Mycorrhizae fungi will grow on, as well as within, a plant’s roots.

It is from that point where they will venture into the rooting medium and create a vast net-like structure of tiny strands of fungi called “hyphae”. This net-like structure dramatically increases the overall size and mass of the root system and helps the plant obtain more nutrients. The plant and fungi exist together in a mutually beneficial relationship. The plant receives elemental nutrients that it may not have been able to absorb on its own. The Mycorrhizae fungi receive food in the form of sugars from the roots. Mycorrhizae fungi are plant species sensitive and not all species of the fungi will form this beneficial relationship with all types of plants. The Mycorrhizae species Glomus intaradices is most beneficial to cannabis plants, and inoculants containing this single specie alone are recommended.

Most beneficial microorganism supplements are water soluble and some come mixed with a colloidal-type ingredient like clay that helps them stick to the roots. Both inoculants can be either applied directly to the roots or mixed with water and applied. When mixed with water the roots can be soaked briefly in the solution or watered in with it after they are transplanted. To transplant, fill the container nearly to the top and make a hole big enough for the roots to fit comfortably. When placing the seedling or clone into the hole be careful not to disturb and injure the roots. After the plant is placed in the hole spread the potting mix around the base of the plant and add, if needed, enough extra potting mix to cover the base of the plant by two or three inches. Water lightly with the microorganism solution and then place the container underneath the lights.

The environment within the greenhouse structure will need to be properly maintained and controlled for maximum growth potential. Temperature might be the most important aspect, specifically during night time and early morning hours. Never let the temperature drop below 60 degrees Fahrenheit because it will lead directly to slower root growth. Day time temps should not be allowed to reach 90 degrees Fahrenheit with a temperature of 75-80 degrees Fahrenheit being optimum. Since the plants will be placed into the greenhouse structure in early April, day time temperatures will likely not be an issue unless it is an unseasonably warm, early spring. If temperatures begin to rise, provide adequate ventilation and air flow or even consider utilizing a shade cloth on top of the structure. In April, night time temperatures will likely dip into the cold range so supplemental heating may be required. For larger greenhouses, a propane or natural gas heater, depending on location and availability, will be sufficient, and for smaller structures electric heaters are an option.

Supplement lighting with t5 or t8 fluorescent lights, using as many as needed to ensure even distribution over all of the plants. Keep the lights about one foot above the top of the plants and adjust them as they grow. The reason for using fluorescent lighting is because they emit light that is primarily in the blue section of the light spectrum. This part of the spectrum is used in the vegetative stage of plant growth and is highly available to the plant during photosynthesis. To maximize plant growth during this stage the plants will need a minimum of 14 hours of light per day. For example, provide the plants with light from 5 AM to 9 PM. While the sun can provide ample light during the peak hours of the day, supplemental lighting will be needed in the early morning and evening. Utilize a timer and program the lights to turn on at 5 AM and then off again around 9 AM when the sun is rising higher in the sky. Likewise, program the lights so they come back on around 5 PM when the sun is beginning to set and then off again at 9 PM. Automating this process will make it much easier for the grower and will ensure the plants receive 14 hours of light each day.

Water the plants when the top one-to-two inches of soil mix is noticeably dry. By sticking a finger into the soil a grower can better judge if it is time to water. Insert a finger, index finger works best, into the soil until it meets the first knuckle. If the soil mix feels moist and chunks of it stick to the finger when it is pulled out, then it is not time to water. If the soil mix feels dry and no chunks stick to the finger, then it is time to water. Use just enough water to moisten the whole container while trying to avoid any run-off from the bottom. Make sure the soil mix is allowed to dry out a bit between watering. If the mix remains saturated the entire time, root growth will slow down and in the worst case scenario this can lead to root death and plant failure. The entire time the plants are in the greenhouse environment they should be fertilized on a weekly basis with liquid nutrients formulated for the vegetative stage of growth. Nutrients that are designed for this stage of the growth cycle will have a higher level of nitrogen (N) and are usually labeled as “grow” or “veg” formula. In addition, weekly applications of compost tea will help sustain healthy levels of microorganisms and provide other beneficial substances that will aid the overall resilience of the plant.

Seasonal Timing

When it comes to a high-performance outdoor cannabis garden, seasonal timing is everything. The plants being grown have the potential to become towering giants, but it takes time and should not be rushed. Like the old saying goes: it’s not a sprint, it’s a marathon. This method is the exact opposite of how cannabis is grown indoors. Indoor plants are grown faster, three months on average, and the result is a smaller plant that will usually yield somewhere between one-to-two pounds per plant. High-performance outdoor cannabis gardens take eight-to-nine months and can yield upwards of eight- to twelve pounds per plant. Do not transplant them into the final outdoor containers until the threat of cold nights and frost has passed. This will likely be in mid-May, but each year can be different. Frost and cold soils will have a serious negative effect on root/plant growth that the plant will have difficulty recovering from. Plants brought out too early may also have the tendency to flower earlier than desired keeping the plant from reaching its maximum potential. If a plant is brought out too late, say mid- to late-June, the plant will not have time grow as large as it possibly could before flowering sets in.

Cannabis plants are photoperiod sensitive, meaning their flowering/reproductive cycle is induced by changes in daylight hours. The plants will continue in the vegetative stage of growth through June as the days become longer. At the end of June the summer solstice is reached and the days begin to get shorter. Daylight hours are reduced each day throughout July and August which triggers a switch from vegetative growth to flower development. Working along with seasonal changes is an important component of a successful high-performance outdoor cannabis garden.

This article is an excerpt from Outdoor Performance Cannabis written by Dustin Fraser and published by High County Publishing. For more information visit

Read More Articles

A Proper Growing Environment Leads to Successful Cannabis Harvests and Maximum Profits

Germinating Cannabis Seeds

Properly Harvesting a Cannabis Crop

Using Polycarbonate to Build a Cannabis Producing Greenhouse

Free Subscription to Professional Marijuana Grower Magazine