Understanding micro- and macronutrients, for example, and their roles in helping plants grow properly to complete their lifecycles, equips cultivators with the knowledge to produce healthy plants with optimal yields.
Biological controls, plant oddities, plant physiology, nutrient lockout, fertility management, water quality and the like are explored and explained in this series. Well-versed cultivators who just need a refresher as well as less experienced growers who are just getting going can both benefit from findings to reduce their trial-and-error growing pains.
For in-depth analysis, findings and best practices, read the following “Cultivation Matters” articles previously published in Cannabis Business Times:
What To Do When Micronutrients Become Macro Problems (August 2021)
Plants require certain micro and macronutrients to thrive. Although plants do not need micronutrients in the same concentration as the meat-and-potatoes macronutrients, they are just as important for plant growth, development and biomass production.
Micronutrients iron (Fe), boron (B), manganese (Mn), zinc (Zn), copper (Cu), and molybdenum (Mo) are all essential to produce healthy plants. With the recommended rates of micronutrients being smaller in comparison to macronutrients (nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S)), it is easy for growers to overapply them. But just because plants require these essential elements in lesser amounts doesn’t mean an imbalance won’t have an outsize impact on crop health and yield.
Excess application of micronutrients can cause nutrient antagonism and imbalance, which limits nutrient concentration and uptake, meaning key elements are unavailable to plants. There is a specific range where micronutrient fertility is optimized, but not overapplied.
The entire article can be read here.
How Biological Controls Can Help You Tackle Aphid Issues (July 2021)
Biological control is a plant protection strategy used in different horticultural cropping systems that minimizes plant damage so that plants are marketable and/or there are no effects on yield.
Biological control involves releasing parasitoids, which will regulate insect and/or mite pest populations. The primary parasitoids and predators used in controlled environments are associated with aphid parasitoids and predatory mites.
Commercially available parasitoids can be purchased from biological control suppliers and then released to regulate insect or mite pest populations of cannabis crops.
The entire article can be read here.
How to Fight Cannabis Pests With Bugs (August 2021)
The following article is the second of a two-part series (first part is above) that describes commercially available parasitoids and predators, which can be purchased from biological control suppliers and then released to regulate insect or mite pest populations on cannabis crops. Here, we examine the predatory mites that attack fungus gnats, mites, thrips, and whiteflies.
Predatory mite behavior needs to be understood before release because their ability to regulate specific insect or mite pests is primarily dependent on feeding habit, though plant volatiles (i.e. odors emitted by plants when fed upon by herbivores that may attract certain predatory mites such as Phytoseiulus persimilis) and dispersal can also affect regulation. Predatory mites are classified into three categories: Type I, II, and III, based on their food preferences and dispersal capabilities among and within plants.
The entire article can be read here.
Funky Stems: What Does Fasciation Mean for Your Cannabis Grow? (June 2021)
As plant scientists, we observe how plants grow and develop over time, and we are intrigued by variations or oddities that occur in growth. Recently, a seed-born cannabis plant in our greenhouse developed abnormal shoot growth with a flattened apical stem. Other cannabis growers have posted images online when they too discover an odd, flat stem.
We grew the plant for two months to observe the advancement of growth patterns. Over time, the shoot tip developed a mass of leaves growing out of the top. As the plant continued to grow, the deformed portion of the stem, which measured more than 3 centimeters across, enlarged and flattened.
This phenomenon is referred to as fasciation. So, what causes this fascinating, distorted growth?
The entire article can be read here.
Can Cannabis Benefit from Silicon? (May 2021)
Silicon (Si) has been touted as a miracle chemical by many. It is the second-most abundant element of the Earth’s crust, at 25.7% by weight. Much of the Si on Earth is tied up in silicate forms, such as quartz, that are unavailable for plant uptake.
Nevertheless, with natural weathering, abundant Si becomes available in the soil for plants. With Si being prevalent on Earth, it has become an important element for some plant species and can improve plant growth and prevent disease. That said, Si is classified as a beneficial element, not an essential one, because it is not required for the plant to complete its lifecycle.
The entire article can be read here.
Ideal Rates of Iron in Cannabis Cultivation Vary Depending on End Goal (April 2021)
When most people think of iron, it’s in the context of construction and manufacturing, and considerations focus more on quality and stress ratings. But iron plays a crucial role in both human and plant physiology. (The metallic taste in blood is from its iron content, as anyone who has bit their tongue will attest.) In the plant world, iron (Fe) is an important part of protein synthesis, chloroplast development, and the photosynthetic process of energy storage in cannabis.
In plants, Fe is an immobile element, meaning it cannot be moved (translocated) within the plant from older portions of the plant to satisfy the demand in newer developing plant portions. This is important information given that nutrient deficiency symptoms will be seen on the new and expanding leaves.
The entire article can be read here.
What Are the Optimal Rates for Magnesium in Cannabis? (March 2021)
Macro- and micronutrients help plants grow properly, obtain optimal yields, and complete their lifecycle. Substantial quantities of the essential macronutrient magnesium (Mg) are necessary for proper plant growth and development.
In plants, Mg is a mobile element that is used in photosynthesis and protein synthesis. Therefore, Mg is often moved (translocated) in the plant from the older leaves to satisfy the demand in newer developing leaves that are often more photosynthetically active. Given Mg is the central atom of the chlorophyll molecule, which converts light energy into essential carbohydrates, Mg is directly related to optimal plant growth.
Cannabis is a determinate plant, which means that once flowering begins, the terminal growing tips develop into floral material. Mg will directly impact the size, quality, and yield of a plant, which will directly impact the grower’s bottom line.
The entire article can be read here.
How to Optimize Phosphorus Fertility for Cannabis (February 2021)
Plants, much like humans, require certain nutrients and minerals to thrive. These macro- and micronutrients help plants grow properly, obtain optimal yields and complete their lifecycle. Aside from nitrogen (N), phosphorus is perhaps the most important of the macronutrients. Phosphorus (P) is essential for energy storage and utilization, root development and growth, flower formation, and metabolic activities in cannabis.
In plants, P is a mobile element that is necessary for many key metabolic processes, in addition to cell elongation and root growth and development. Therefore, P can be moved (translocated) from older growth segments of plants to satisfy demand in newer, developing plant portions. This is important to note, given that nutrient deficiency symptoms will appear in older leaves as the plant moves P resources into the new and developing leaves and other sinks such as developing flower buds.
The entire article can be read here.
3 Tips to Avoid Nutrient Lockout in Cannabis (January 2021)
One of the primary goals for cannabis cultivators is to optimize plant growth for stronger, healthier yields. To optimize plant growth, monitoring and managing nutrient levels is essential; however, numerous factors can affect nutrient availability and uptake for cannabis plants.
As growers know, cultivation is a balancing act of providing adequate nutrient levels in proper ratios, and, most importantly, ensuring that the substrate pH is within the recommended range. Each of these factors properly applied together optimize plant growth, but if one factor is out of balance, the plant will suffer.
Nutrient “lockup” or “lockout” is when a particular nutrient is unavailable for the plant to uptake. This is usually caused by an elevated substrate pH, a situation that has plagued cannabis growers for many years.
A second problem is improperly balanced nutrient levels. This is referred to as an antagonism. In addition, one must ensure that adequate levels of fertility are provided. While these can all limit nutrient availability, their fundamental causes are different. And perhaps the most important factor is substrate pH.
The entire article can be read here.
How to Establish a Cannabis Nutrient Monitoring Program (November 2020)
Fertility management can be challenging for many crops. To ensure your plants are receiving the fertility they require, a stepwise nutrient monitoring program that examines both systems and plants should be implemented.
When setting up a holistic greenhouse or indoor monitoring program, it is important to monitor and test each step along the supply chain, examining the irrigation pipes and flow of water and nutrients. The main steps include:
the water sourcethe mixing tank and injectorthe drip emitters or delivery systemthe substratethe plant.At each step, complications and challenges can arise. By taking a “pipe-to-plant” approach, you can determine where along the supply chain problems arise and identify them early to prevent costly ramifications to plant growth and development.
The entire article can be read here.
How Does Your Cannabis Fertilizer Recipe Compare? (October 2020)
Fertilization management can be considered both a science of what plants require and an art of how nutrients are supplied. The major nutrients taken up by plants are nitrogen (N), phosphorus (P), and potassium (K). With these three elements being the heavy lifters, most fertilizer programs focus on delivering NPK to the plant.
The other elements included in fertilizers are still essential but generally are provided at constant levels. We evaluated two commercial cannabis fertilizer programs developed by suppliers who were willing to share their recipes and compared each program to our cannabis fertility research program at North Carolina State University (NCSU).
The entire article can be read here.
How to Monitor Irrigation Water Quality and Correct Imbalances in Container-Grown Cannabis (September 2020)
Water is the single largest input for growing cannabis and therefore an essential resource for growing healthy plants. Plants, by weight, are comprised of 90% to 95% water.
Elements in irrigation water can affect plant growth, especially in container-grown plants, due to those plants’ restricted root masses and the high potential for change within the soilless substrate because of its relatively low buffering capacity, or the ability to regulate pH changes. Because of this, it is important to regularly monitor your irrigation water to be sure it is not creating nutrient imbalances and inhibiting plant growth.
The entire article can be read here.
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