Plant nutrient basics are explained, along with proper mineral values used to grow optimized cannabis flowers. Learn how we mix and make all of our own nutrients and see lab results of the finished product!
The use of soilless mixes and increased research in nutrient cultures and hydroponics as well as advances in plant tissue analysis have led to a broader understanding of plant nutrition. Plant nutrition is a term that takes into account the interrelationships of mineral elements in the soil or soilless solution as well as their role in plant growth. This interrelationship involves a complex balance of mineral elements essential and beneficial for optimum plant growth.
Plant Nutrient Basics
Numerous elements are required for proper plant growth. Air and water supply some of these elements including carbon (C), hydrogen (H) and oxygen (O), while the growing media is the principle source of all other nutrients. Plant roots must mine the growing media in order to find these much-needed macro and micro nutrients.
Macronutrients are nutrients used by the plant in the largest amounts. The primary macronutrients include Nitrogen (N), Phosphorus (P) and Potassium (K). Secondary macronutrients, are used in lesser amounts and include Calcium (Ca), Magnesium (MG) and Sulfur (S).
Micronutrients are used in the smallest amounts by plants and include: boron (B), copper (Cu), chlorine (Cl), manganese (Mn), molybdenum (MO), iron (Fe) and zinc (Zn). Even though these nutrients are used in trace amounts, the omission of even one will cause plants not to grow and reproduce.
Plants uptake nutrients as hydrated ions. An “ion” is an atom or group of atoms which has gained or lost one or more electrons, and therefore carries a positive or negative charge. This “charge” enables ions to either repel or attract other ions. Ions with a positive charge (+) are called “cations” and are attracted to a root hair containing negative (-) ions called “anions”. In this way, nutrients are brought close to root hairs so they can be absorbed.
At Golden Apple Cannabis Co. we supply nutrients to the plants in the pure mineral ion form. Our nutrients are sourced from seawater and mineral deposits. Any unwanted and nuisance salts are removed by a process called fractional crystallization.
There are particular levels of the various mineral elements (macro and micro nutrients) that we look to achieve. We use two separate nutrient formulations. One for the vegetative stage of growth, and another nutrient formulation for the flowering stage of growth.
For the vegetative stage of growth and up to the third week of the flowering phase, we generally shoot for the following mineral value parts per million (ppms):
By knowing these optimal values for growth and taking into account the lab results both from the water sourced and what is contained in the media we then develop a nutritional recipe for our plants. We input the values into the HydroBuddy nutrient calculator designed by Daniel Fernandez. HydroBuddy is an excellent and free open source nutrient calculator. (If you use it, we encourage you to donate a little to Daniel to encourage the development of the tool.)
For this example, we made 7 liters each of a two-part hydroponic nutrient solution. We’ll call the them parts A and B.
On the main page is where we input our target ppm values for each element:
Next, after performing the calculations HydroBuddy tells us how much (in grams) of each element to mix into our 7 liter nutrient formulation.
One thing to note: we do also use potassium silicate (Si) in our nutrient formulation program. We do not calculate this element with HydroBuddy, although it is incorporated into our lab results below.
Silicon is the second most common element in the earth’s crust. It is widely regarded and agreed that plants require 17 key elements to successfully develop. These are comprised of macronutrients; nitrogen, phosphorous, potassium, calcium, magnesium and sulphur, and micronutrients; iron, manganese, boron, copper, molybdenum, zinc, chlorine and nickel. Plus, the obvious elements of carbon, hydrogen and oxygen.
With Silicon being found in such abundance in plant tissues, there is now an argument that it should be considered as a relevant macronutrient. If you have ever grown hydroponically and thought that your plants seemed a little weaker or more susceptible than previous crops grown in soil, it may be due to a lack of Silicon.
Potassium silicate is used at a rate of .5 grams to 1 gallon of reverse osmosis water. This will leave us with a bump of around 35 ppm of (K) potassium and 33 ppm (Si) of silica added on top of the values reported from HydroBuddy.
So, after making the nutrients we then send them off to the JR Peters laboratory to check our values and verify that they are correct.
For the flowering phase of plant growth (week 4 of flowering to harvest) we use slightly lower nitrogen and calcium values, and raise the phosphorus and potassium values. The ppm values of each element of our flowering formulation is the following:
We repeat the process of plugging in our values into HydroBuddy, mixing and making the flowering nutrient formula, then we send it off to the lab to make sure we’re on base and the formula actually has the values that we are looking for.