A cutting taken from a mature female cannabis plant intended for propagation.

Coconut Coir

Coconut Coir is the husk (mesocarp) of the coconut fruit that is processed and composted to produce a fine particle growing substrate. The husk contains 75% fibers and 25% pith on average and the fibers are separated from the pith to produce the final “coir pith” product. Advantages: Coir has good water holding capacity, a very high cation exchange capacity (CEC), and good rates of air filled porosity. The pH of coir will range from 4.5 to 6.5 depending on the area of coconut palm production and processing techniques. Disadvantages: Because coconut palms typically grown in close proximity to the ocean, levels of chloride and sodium can be higher than optimal so the coir must be properly leached and composted. Due to high levels of potassium naturally found in coir, the end product must be “charged” with calcium and nitrogen to balance the cation levels.


The female cannabis plant has a main cola, a grouping or cluster of flowers growing cohesively. Colas are buds that form on the tip of the stem of the cannabis plant. Often, small colas can grow between the foliage or on the plant’s lower branches. These parts of a cannabis plant are much smaller than the main cola found at the top of the cannabis plant.

Color Rendering Index (CRI)

Often overemphasized in the context of horticultural lighting, CRI stands for color rendering index. This measurement quantifies a light’s ability to illuminate plants or any other object reliably without color distortions compared to a natural and/or visually-ideal light source. Typically this is a scale from 1-100, with 100 being closest to “standardized daylight.” A light source with a CRI of 30 would be considered a heavily distorted illumination. For example, ceramic metal halide lights traditionally have very high CRI (typically 90+). A classic Tri-Band LED that favors heavy reds and blues (purple lights) has very poor CRI ratings that are often below 50. Color Rendering Index does not really affect your plant growth. Still, you should be aware that you may find identifying plant health issues like toxicities and deficiencies under the LED difficult because you won’t be able to see the ‘true’ colors of the symptoms. HPS lamps are another popular light source that traditionally has a poor CRI. Some simple solutions for working with lights that have poor CRI would be to use color-correcting grow room glasses or add a standard light source to use when you’re inspecting the plants for problems.

Correlated Color Temperature (CCT)

Many lamps generate light by means other than a filament, which creates light with slightly different. In this case, the actual metric used is CCT or correlated color temperature. A common example of CCT is seen when describing fluorescent T5 bulbs, but this has been used to describe the visual spectrum of high pressure sodium lights and LED’s as well. Lamps marketed as 4000K and lower will emit more red light, lamps which will be good for flowering plants and lights rated 7000K and above emit more of a blue spectrum which will be good for seedlings and vegetative growth. Lamps with a Kelvin between 5500-6500 will emit the closest spectrum to natural daylight. It’s important to note that color temperature, CCT and Kelvin only refer to the visual spectrum emitted from a lamp.


The cotyledons are the first leaves appearing on the cannabis seedling after sprouting. Cotyledons are also called seed leaves and typically grow as a pair of tiny green leaves. The weed plant can begin photosynthesis because the cotyledons contain chlorophyll. The energy produced from photosynthesis allows the marijuana plant to grow. The cotyledons will shed, allowing other parts of a cannabis plant to mature and continue to grow and absorb nutrients.

Crop Steering

Crop steering is a plant growth management practice that manipulates the environment (light, climate, irrigation) to encourage plants to grow a certain way. Next to light intensity, it’s the most important tactic you can use to manipulate yield.

Daily Light Integral (DLI)

DLI, or daily light integral which is a measurement of the total amount of usable light that reaches a plant every day. This is something that greenhouse growers are concerned with since the amount of light they get each day is weather dependent. For indoors, if you are using a grow light only, you will know the output of your light every day and PPFD is all you need to know. The DLI is a cumulative measurement of all the photons that reached the plants’ canopy over the course of the 24 hour day. This is expressed as moles per square meter per day (mol/m2/d). A simple analogy – Think of DLI as the total amount of snowfall after a blizzard as opposed to how fast the snow was accumulating (which would be PPFD in this analogy). Like PPFD, DLI is a spot measurement, so it is important to take multiple readings from several different locations within a coverage area.