A brief but comprehensive overview of the most important aspects to growing your own cannabis. 

For those who have never grown before or those who want to take their garden to the next level, we've compiled these easy to digest principles backed by experience and education. 

The long term success of any grow is achieving and maintaining the best possible combination of environment and nutrition; or you can think of what all these elements entail with this acronym, L.A.W.N.S: Light, Air, Water, Nutrition, Substrate. When all of these components are paired with well-bred genetics, the potential yield and quality are greater, and so is the actual return. 

These are also sometimes referred to as defining and limiting factors; if one aspect does not achieve to it's fullest potential, no amount of supplementation from other factors can improve the outcome. The factors in order of importance are:

  1. Genetics and Environment - Defining factors
  2. Water and Nutrition - Limiting factors
  3. Pests/Mold/Human Error - Reducing factors

If your environment is poor, no amount of water can force a plant to produce what we expect. If the genetics are incapable of delivering a trait we desire, no nutrition regimen can change that. If a plant is subjected to intense heat and drought, it is more susceptible to pests. If a plant is kept too wet in moderate temperatures, we may incur mold on the surface and inside flowers. 

So, let's take a look at how we can get the best results in each of these arenas.

ENVIRONMENT

  • Temperature/Humidity

“Cannabis tolerates a wide range of environmental swings but may vary from cultivar to cultivar. Maintaining a balanced and constant atmosphere is desired to avoid any possibility of ill effects from either heat or cold stress. Typically, transpiration is best observed in cannabis plants when the temperature sits between 75-81 degrees. To complement this, the relative humidity should stay between 50 and 70%, depending on the life stage of the plant.”

Digital Thermometer/Hygrometer & Data Logger

  • Air Exchange

“If you are growing plants in a contained or sealed area, a fresh supply of oxygen can improve both physical health and rate of growth. As plants respirate and release oxygen into their environment, a purge of stagnant or built-up gasses will provide more room for regular respiration and CO2 uptake again. Conventionally, recommendations are to introduce new oxygen and remove the old at least twice every hour. This is accomplished by using a combination of inline fans, ducting, and automatic timers.”

In-Line Fan & Filter Configuration

(Photo Source: ACInfinity.com)

“Circulation is not to be confused with either cooling or air exchange. Circulation is necessary to physically remove any humidity which hovers directly over the leaf surface. When this humidity is removed from the immediate area of the leaf surface, more space is created by which the plant can release more moisture and oxygen, and therefore transpire at a regular rate.”

Oscillating Wall Fan and Clip Fan

  • Vapor Pressure Deficit
    • Pro Tip

“Combining all varying aspects of temperature, relative humidity, air exchange, and circulation yields a principal that tells us that transpiration can be optimized and is complementary to each individual’s environment. Examining a vapor pressure deficit table can inform us of what our ideal conditions should be to best stimulate growth and make the most of our environmental inputs.”

VPD Table - Orange is ideal pressure for transpiration

  • Lighting
    • Requirements for each stage

“As a cannabis plant grows and matures from a seedling into its completed form, the lighting and energy derived from lighting increases to complement each stage of development. When choosing a light, evaluate your growing space and environmental limitations.”

  • HID vs. LED

“High intensity discharge (HID) lighting systems are composed of lamps, sockets, ballasts, and in most cases a hood or containment structure. The ballasts conduct electricity and capacitance in an evenly measured manner which powers the lamps; the lamps produce gas around a heated element which generates luminescence. Typically, HID systems use a higher wattage per hour but dispense a very high amount of energy output which plants use in photosynthesis.”

HID Fixtures and Socket Bulb

“Light emitting diode (LED) lighting fixtures are composed of a variety of silicone-based chips that emit a very efficient amount of light and energy relative to how small they are or how little power they require. By using many LEDs in combination, a fixture can create a field of light that attempts to mimic sunlight or HID systems for a fraction of the electrical input.”

LED Fixtures

  • MH/HPS + Differences in temperature color

“When selecting a HID or LED fixture, it’s important to recognize the differences and roles that different spectrums and so-called ‘temperature-color’ play in affecting a plants response and growth habits. For instance, a metal-halide bulb used in a HID system generates a temperature-color which is conducive for vegetative growth. But an LED fixture may incorporate several different emissions together that can be manipulated for different stages of development. A high-pressure sodium bulb, though, is conventionally thought to generate a superior spectrum for flowering plants.”

Color Temperature Scale - Measured in Kelvin

  • CO2

“Carbon dioxide is a necessary component of plant growth and health. An inadequate supply can prohibit a plant from reaching its maximum potential. A constant supply of CO2 promotes metabolic processes and respiration.”

 

Organic CO2 Dispersal Parcels

  • Filters & Odor Control
    • “Cannabis plants emit a scent that can be over powering or attract attention. Attaching a charcoal carbon filter to your inline fans will scrub the smell from your exhaust air, thereby preventing any unwanted or undesirable scents. These should be sized correctly for your growing space and the number of plants being grown.”

Carbon Filters with Pre-Filter

 STAGES OF GROWTH

  • Germination – 18-24 hours light – 24-30” Above canopy (LED)/8-10” Fluorescent
    • “To break the dormancy of a seed, moisture and warmth are preferred. Insert your seed into a starter plug or block of medium which has been pre-wetted and lightly fertilized. Place the starter on a warm surface. In as few as 2 days or as many as 20 days, your seed should begin to sprout and grow a radicle root and small cotyl leaves. Too much warmth or moisture, however, can hinder the process. Attempt to keep the starter just under 80 degrees Fahrenheit and consistently moist but not soaking.”
  • Seedlings – 18-24 hours light – 24-30” Above canopy (LED)/ 8-10” Fluorescent

“Once a seed has germinated and is above ground, light is necessary to provide energy. Continue to provide moisture, warmth, and light while the plant develops full leaves and nodes. This takes place over a period of 4-6 weeks. Full strength fertilizer is not necessary until the plant is well established. Most products include guides regarding dosing and life cycle stage requirements. At this stage (and at every transplant), it is wise to inoculate the beginning root mass with beneficial bacteria that enhance uptake of nutrition. Once roots are visible, apply the inoculant and place the plug with your plant into a small pot and medium of your choosing.”

  • Clones – 18-24 hours light - 24-30” Above canopy
    • “From an existing established plant, one may select any shoot which is at least 4-6” long and excise it. Removing all but the top two nodes and leaves will produce what is called a clone. It is genetically identical to its mother. By placing this clone in a pre-wetted and lightly fertilized starter plug, over 10 to 14 days, roots can be induced to form and establish as a seedling does. This process reduces the vegetation time of a seedling by upwards of 3-4 weeks. Use of rooting gels containing hormones and specially formulated fertilizers can greatly increase the rooting percentage rate.”

Mother Plant furnishing many clones

Tray of Clones

  • Veg – 18 -24 hours light – 18-24” Above canopy
    • “Once a plant has 5-10 nodes, it may be preferential to snip off any of the top two or three nodes. This encourages wider and numinous branching by any nodes below those you have removed. Be conscious of your available space. After multiple weeks of watering and allowing your branches to spread out, you may find that your roots have completely taken over your container. Prepare a container with two to three times the volume of the current container with your medium and inoculant. Remove the plant and roots from the old container and place them in the new container. Fill in the sides and any gaps, finishing the process off by watering lightly the new media.

Topped Plants

Plants in Vegetative Phase

  • Flowering – 12 hours light – 12-24” Above canopy
    • “When your plant is well enough established, reduce the amount of available light hours to a maximum of 12 per day. This shift in available energy signals to the plant that it is time to produce flowers. This process has a finishing time of anywhere from 7-16 weeks depending on genetic variety.

      Stretch & Diffusion
    • “Be conscious of any height restrictions during this period. Your plant may double or even quadruple in size. You will also witness exponentially more branching and node presentation than seen in the vegetative stage. As more mass is created, the available nutrition is diffused in the plant and you may be forced to compensate by adjusting your fertilizer according to need and stage. Invest in support for branches which begin to become too top heavy.”
  • Nutrition Demands

“A moderate increase in potassium and phosphorous is generally expected. Especially during weeks 4, 5, and 6. Nitrogen is still necessary but not in the quantities observed during vegetation. Nitrogen amounts can be gradually lowered throughout the flowering phase.”

  • Plants are ready to harvest once a majority of pistils have turned brown and trichomes appear to have a good mix of amber and cloudy hues.
  • Drying

“Plants can be chopped down and harvested whole, cut into arm length segments, or you may remove buds from the stem entirely. The larger the mass of harvested material, the longer it may take to dry. A whole plant may take 10-14 days to dry, but individual flowers may be ready as soon as 8 days. What is key in any scenario is the removal of stagnant air, proper circulation, stable temperatures, and stable humidity. In this stage, lowering the temperature and humidity can prevent the formation of any biological contaminants while still removing excess carbon from leaves and flowers. However, allowing humidity to remain lower than 50% for an extended amount of time may result in brittleness and an over-dry final product."

Hang-drying plants

  • Curing & Storage
    • By trimming the leaves and excess material away from the flower, you nearly have a final product. Place the flowers in a sealed container and check them daily to release any moisture which may continue to build up post-harvest or drying. Timing this process and releasing less and less air at each period will yield a product which no longer releases excessive moisture but maintains its turgidity and form.

TerpLoc Grove Bag - Breathable material which does not require burping

SUBSTRATE & CONTAINERS

  • Soil
    • Soil has many compositions and nutritional inputs. Most soils of use to cannabis growers are a mixture of sand, loam, light amounts of silt, and aeration. Loam may contain a certain percentage of clay particles but its primary input is to bring organic materials and humus into the equation. By combining sand, organic material, fine metal and mineral particles of silt, we can create a substrate with many sites for nutritional elements to cling onto and dissolve at a preferable rate. All of the sites inside soil are constantly exchanging nutritional elements, oxygen, and hydrogen. The goal is to keep the sites replenished as soon as they move from the soil to the plant. Cannabis is a heavy feeding plant in most instances. While vegetables and fruits may need only one or two fertilizer inputs in a season, cannabis may require constant replenishment depending on its size, the structure of the soil, and the environment in which it grows.

  • Soilless
    • Peat moss: Peat(moss) is a very dense composition of decayed organic matter and carbon. It is formed by thousands of years of compaction, carbon sequestration, and the multiplication of moss species bodies which fix water and carbon from their surroundings. It has more sites and a larger capacity than your average soil, which makes it attractive as a substrate for growing plants. With more sites, nutrition could be stored longer and in greater capacity. However, it is not renewable and requires attention to aeration. Because it is so dense and its water-holding capability is high, including aeration in the form of perlite, pumice, or rice hulls can allow oxygen to move in a freer fashion between particles and ultimately to the roots.
    • Coco coir: Coco coir is the ground husks and hulls of coconuts. Its capacity is lower than that of soil or peat but it retains moisture and oxygen in a very evenly balanced manner. Since it has fewer sites, growers can move nutrition in and out of the substrate and into the plant in a very quick fashion. While a well rooted plant will only require water or fertilization every few days in soil or peat, a plant in coco can access moisture and nutrition so quickly that one can achieve a system of many feeds a day. This can help a plant to become bigger- quicker, although it may demand more maintenance and constant attention.

 

  • Rockwool
    • Rockwool is wind-blown basalt which is super heated, separated into fine threads, and then recompacted. Ordinarily, rockwool (or stone wool) should repel water but when loosely composed, retains it instead, as well as nutrition. Like coco, its ability to exchange oxygen, water, and nutrients can become so fluid that multiple feeds a day can be achieved, allowing for faster and larger growth. The bricks are also preformed and cut into specific sizes which allow for easier management of its foot print.

  • DWC
    • Deep water culture allows for (almost) any soilless medium to begin the rooting process but then allows the roots to grow into a reservoir of nutritional solution; in effect, the water itself is the substrate. So long as nutrition is balanced and pH remains stable, the reservoir can service the plant by itself without any need for soil or exchange of nutrition.
  • Hydroton
    • Hydroton are clay pebbles which can retain moisture and nutrition but are intended as a buffer between a plant’s root zone and a reservoir in a deep-water culture system. It allows oxygen to freely pass while providing the roots support and structure.
      A DWC system using hydroton as a substrate
      (Source: Instructables.com)
  • Conditioners/Castings/Compost/Amendments

Conditioners are recommended for improving the structure of soils, whether they have been used previously or not. Any soil which has either become too dry, or for too long has been wet, can benefit from the aeration and increased site capacity of conditioner inputs. These can include peat (moss), composted bark or leaves, manure, or other organic materials.
             
Amendments, on the other hand, specifically boost the nutrition and performance of soil. The inputs can be organic or mineral but it is understood that a certain fraction will be immediately available and another portion will require time, moisture, and active bacteria to mineralize further. Amendments can be added during the growing process or in between crops when recycling substrates (including coco or peat.)




Worm castings can act in both categories as an amendment or a conditioner. They are also rich in bacterial activity which can be used (top-dressed) throughout the growing process.





  • Compost can also act in both categories. So long as the finished composted result is rich in both nitrogen and carbon, it can contribute nutrition and bacteria as well as loosen hard-pan and clay soils.
  • Porosity
    • Soils and other substrates require aeration or all of the particles risk trapping water indefinitely. Moisture and nutrition are important to healthy roots and plants but so is oxygen. Many soils and peat products available for purchase contain elements which provide aeration and allow water to pass between particles so that the medium does not become water logged. This can include bark/woodchips, rice hulls, perlite, vermiculite, pumice, lava rocks, etc. Some coco coir products contain perlite but it can be used just as easily without. Coir and rockwool containing established plants do not stay as saturated as long as their soil, compost, or peat counterparts.
                    

NUTRITION & MOISTURE

  • Organic vs. Hydroponic
    • “These terms describe the source of nutrition by which plants are fed. Organic allows for the weathering or decomposition of materials which release stored nutrition over time. This can be obtained from animal mass or waste, plant matter, the byproduct of micro-organisms, and all combinations of these materials that have been composted and digested. Hydroponic solutions are specifically formulated to contain a guaranteed amount of elemental nutrition which is normally readily available. They are concentrated and dispensed in small measurable amounts. Whether your source of nutrition is organic or hydroponic, all crucial elements must be in a mineralized form for plants to absorb and use them. Both are acceptable and serve different aspects of convenience, sustainability, and production.
  • Macros N-P-K
    • “The three most important elements in any nutritional input (besides carbon, hydrogen, and oxygen which are a given) are nitrogen, phosphorous, and potassium.
      • Nitrogen makes up a substantial portion of our atmosphere and internal mechanisms in almost all living things. In plants, nitrogen is key to producing DNA, amino acids, proteins, enzymes, respiration and maintenance cycles. Nitrogen is the driver of cell elongation and division, and therefore total plant mass. Soil or media rich in nitrogen will produce taller trunks, thicker branches, and wider leaves.
      • Phosphorous, like nitrogen is key in forming DNA and essential compounds but plays larger roles in cell-to-cell functions. Usually, Phosphorous is not readily available when transitioning from soil sites into the plant and additional mineralization efforts are needed to transition it into a form which a plant finds acceptable. Overall, a plant requires a lot less phosphorous than other macro nutrients but without it, all processes suffer and it can become stunted very quickly.
      • Potassium is consumed in very large quantities and acts as a regulator in cell shapes, function, carbon/hydrogen exchange, and energy activation. Potassium is never found as a standalone element in nature and only as a salt. Potassium must constantly be refreshed in any growing system as it is constantly being depleted.
      • Calcium & Magnesium are popularly regarded with less interest but are nonetheless incredibly important and without them, other functions suffer and collapse. Calcium is the lead currency of all plant metabolism and systems. Calcium, like phosphorous, is slower with regards to plant uptake and likewise moves slower once inside the plant. However, unlike phosphorous, the amount of calcium found in the plant will directly and proportionally affect the performance of other elements and therefore we should ensure that all media and plants are heavily supplied with it. Magnesium is key in creating chlorophyll but at higher concentrations can lock out potassium or calcium. A minimum is required for healthy, green vegetation and full fruiting blooms.
    • Micros
      • Zinc, Iron, Boron, Molybdenum, Manganese, Chlorine, Sulfur, Copper. (Debated: Silicon, cobalt, sodium, nickel)

These additional elements are required in miniscule quantities. It is very uncommon to experience a deficiency in these elements without first being aggravated by other issues stemming from macro deficiencies or lock outs. Micro deficiencies are usually remedied much easier than macro deficiencies but exceptions exist.

  • Mobile vs. Immobile
    • All of the elements listed experience some mobility or lack thereof in a plant. Nitrogen, potassium, magnesium, phosphorous, chlorine, zinc, and molybdenum are all mobile and can move semi-freely within a plant to self-correct issues of deficiency. To test if a deficiency is the result of a mobile element, you will be able to observe discoloration or malformation on older leaves first. This tells us that nutrition which is stored in older, larger growth is supplying new growth with the required elements. If symptoms are present in newer growth, it signifies that it cannot be corrected or compensated by anything in the existing tissue and we can infer that the deficiency is an immobile element.
  • Balance
    • The balance and different requirements of cannabis nutrition are debated and vary by which medium one grows in. Some descriptions are prepared in percentages and some recommendations are based upon ratios. It is our own recommendation that whether in soil or soilless, a strong base of calcium should always be included in your regimen. Otherwise, achieving balance is the best and all macros should be concocted at a ratio of 1:2:1 (N-P-K). This phosphorous number is doubled because in reality, only half (or less) will ever be available in a formulated solution; therefore, in practice we actually achieve 1:1:1.
    • Example: 100ppm nitrogen, 200ppm phosphorous, 100ppm potassium is actually a nearly balanced solution. The same applies when constructing a soil with amendments and minerals. Keeping Nitrogen and potassium at a 1:1 ratio while increasing your input of phosphorous will produce a balanced soil solution.
    • While N and K should be 1:1 in soil, the total cannot exceed 10% of the total nutrition. Too much potassium will preclude calcium and other elements from achieving a foothold in substrate.
  • Schedules

Conventionally, Nitrogen is most heavily utilized during the vegetation stage. Phosphorous and potassium are then slated to take its place once flowering has begun. During the flowering phase, it is generally expected that a plant will begin to produce more branches and nodes. Once this happens, the available nutrition is diffused and therefore not as strong as its original concentration. So extra P and K are supplied to compensate for this increased need.

  • pH/EC/PPM
    • pH tells us the alkalinity or acidity of a solution. Cannabis prefers a slightly acidic soil environment. Depending on your medium, a pH value of 5.5-7.0 is acceptable in feeds and substrate.
    • EC is the electrical conductivity of a solution. It is a calculation of the strength of a solution based on its elemental content.
    • PPM is parts-per-million (of one liter of solution). Nutrition is very diluted and is thusly measured in millionths.
  • Humic acid/Fulvic acid
    • Humic acid (from Humus) is derived from natural, organic material that continues to enhance soil conditions by and for microorganisms. The longer that a soil is undisturbed and trading in carbon and hydrogen with root material, the finer and more rich humus becomes. The addition of humics or fulvics to a container or garden system simulates aged earth and encourages greater root health and nutrition uptake.
  • Mycorrhizae
    • Mycorrhizae is a type on fungal bacteria which symbiotically binds with the roots of certain plants. The fungi receive water from the plants and the plant receives nutrition that is converted efficiently by the hyphae of the organism. Introducing the mycorrhizal fungi to the root system is sometimes referred to as inoculation because additionally, certain strains of the beneficial bacteria such as these prevent root rot or other mechanical damage from insects or harmful organisms.

 INTEGRATED PEST MANAGEMENT

  • Prevention
    • A well rounded IPM regimen starts with prevention. This means going out of your way to make your growing area inhospitable to mold or pests. These efforts are worth more than any fungicide or pesticide put together. Constant scouting and applying deterrents even when no pressures are present can help ensure a continuously clean environment.
  • Pests
    • Preventing pests begins by keeping your space clean. By allowing clutter, dust, excess moisture, or dead leaves to reside in proximity to your plants, you may invite unwanted attention from pests. Similarly, some pests are moisture-borne and can arise from pots/organic materials that stay too wet for too long. Allow proper drying cycles in your pots and keep all grow spaces clear and clean.
    • Additionally, the deployment of beneficial insects which feast on the insects which would seek to harm your plants is cheap and effective. These insects do not feed on plant material and simply leave the area if no prey insects are nearby.
    • Neem oil is made of many components. Azadirachtin is the most active. It reduces insect feeding and acts as a repellent. It also interferes with insect hormone systems, making it harder for insects to grow and lay eggs. Azadirachtin can also repel and reduce the feeding of nematodes. Other components of neem oil kill insects by hindering their ability to feed. However, the exact role of every component is not known. Neem oil insecticide works as a systemic in many plants when applied as a soil drench. This means it is absorbed by the plant and distributed throughout the tissue. Once the product is in the plant’s vascular system, insect’s intake it during feeding. The compound causes insects to reduce or cease feeding, can prevent larvae from maturing, reduces or interrupts mating behavior and, in some cases, the oil coats the breathing holes of insects and kills them.
    • Other essential oils are shown to be effective at deterring and killing adult insects. Not all of them are effective at killing larvae, though. It is recommended to do multiple applications a few days apart to ensure that insects at all stages of life-cycle are being addressed.
  • Fungus/Molds
    • Prevention of molds, again, begins with cleanliness. However, no matter how effectively surfaces are cleaned, biological contaminants are constantly invading and colonizing plant material and sub-soil zones. By maintaining a consistent and well-matched environment, molds and fungi are not given the opportunity to begin growth on plants or soil surfaces. Excess humidity, lower temperatures, minimal lighting, and minimal air-flow together create conditions that break down protective barriers that plants inherently use to ward off bacteria.
  • Pesticides & Fungicides
    • Never use any pesticide without first examining the label. The directions and usage rates are crucial. Inhalation can be dangerous to humans and pets. It is recommended to dim or turn your lights off entirely when applying them or leaves can be burned. Use in a ventilated area and dispose any excess by following the directions on the label.
    • These products can be applied as a foliar or as a drench. By using both approaches, you can be sure that you are treating all areas of the plant- the leaves and the roots, which if damaged can affect growth or yield.
  • Adjuvants & Surfactants
    • These products are useful in spreading your products evenly across a leaf surface. Otherwise, the moisture may bubble up and not completely coat the surface as one would expect. Usually, very little is necessary to make a complete solution.
  • Biological Controls
    • Specific predatory insects can hunt and prey on other insects which would bring harm to your plants. They can be broadcast over the leaves and stems of a plant; they can be applied to the top of containers, or; they can be watered directly into the substrate in your containers. Typically, these insects are very tiny and, in some cases, microscopic. Then, there are specific predators for each prey and life cycle stage of harmful insects. Avoid deploying these insects before applying pesticides or fungicides.
  • Half-life
    • Pesticides and fungicides have differing half-lives between ingredients. It’s important to research the half life of any product you apply to your plants. Some products may be used up until the day of harvest. Others simply take too long to break down and residues can be observed in the final product.