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Feeding Schedule for Soil

Feeding Schedule for Soil

Feeding schedules are designed to ensure that cannabis plants get all the nutrition they need throughout the three stages of their growing cycle. The best way to keep track of them is by using a feed chart and feeding the plants on the same day each week. Some growers use the feed charts provided by nutrient companies while others make changes to them as needed based on personal experience with different strains, environments, and growth stages.

For novice growers, the most important thing to realize is that cannabis plants have substantially different nutritive requirements depending on what stage of growth they are currently in. Determining the unique nutritional needs of individual strains is somewhat of an art. It requires practice and experience. Novice growers can start off on the right foot by learning how to read feed charts and how to adjust them based on a plant’s response. Read on for more details.

Reading Feed Charts

Feed charts are broken down into simple grids and are typically divided into three tables based on the plants’ growth stage. They offer information about what type of fertilizers or foods to add to the soil, how much of them to use, and what pH to maintain during each stage of growth. Reading feed charts is simple once growers understand what each column means.

Time Frame

The first table will describe the nutritional needs of seedlings, which are cannabis plants less than three weeks old. The second table applies to the vegetative stage, which typically lasts around a month.

The last table should be the longest. It describes the nutritional needs of flowering cannabis plants. Keep in mind that the time frame used in feed charts won’t always perfectly reflect how long an individual plant will remain in the vegetative or flowering phase.

Suggested Nutrients

Cannabis plants derive nutrients from both mineral and non-mineral elements. To grow quickly and produce quality flowers later in life, plants need plenty of Nitrogen (N), Phosphorous (P), Potassium (K), Calcium (Ca), Magnesium (Mg), and Sulfur (S). These macronutrients are all derived from the soil, while the plants’ leaves pull Carbon (C), Hydrogen (H), and Oxygen (O) from the air.

In addition to these macronutrients, cannabis plants also need micronutrients. These are included in most commercial fertilizers. They include Zinc, Iron, Manganese, Molybdenum, Chlorine, Cobalt, Silicon, Boron, and Copper.

To complicate matters further, cannabis plants need different concentrations of these nutrients during different stages of growth. The best solution is to purchase plant foods or fertilizers formulated specifically for cannabis plants in their seedling stage, vegetative stage, or flowering stage.

Not all feed charts produced by fertilizer or plant food manufacturers include detailed information about concentrations of these micro- and macronutrients. That information can typically be found on their products’ labels.

Dilution Rates

Dilution rates can be listed as parts per liter or parts per gallon. They may be listed in grams or teaspoons depending on the quantity of plant food or fertilizer to be added to water.

Many growers choose to use distilled water for mixing plant foods and liquid fertilizers. The distillation process removes chemicals and minerals from the water, leaving it clean and free of contaminants. This ensures that the nutrient levels in the mixed food will be accurate.

EC and PPM

EC, short for electrical conductivity, refers to how well the liquid food or fertilizer conducts electricity. Distilled water typically has an EC of zero, since all the minerals have been removed during the distillation process. Adding mineral nutrients to distilled water increases the EC because it adds ionic salts, which have positive and negative charges.

The EC measurement listed on feed charts reflects the amount of plant food or fertilizer added to the water. The concentration of nutrients can also be measured on the scale of parts per million (PPM), also referred to as the total dissolved solids (TDS) scale.

These numbers refer to the concentration of nutrients in the liquid food prior to application. Once growers add the solution to their soil, the EC or PPM balance will be altered by evaporation, irrigation, and the plants’ nutrient uptake. Under-watered soil, for example, will have a much higher EC, reflecting an unhealthy concentration of salts around the plants’ roots. It’s important to provide plants with the right amount of hydration without over-watering.

Solution pH

Cannabis plants prefer to grow in slightly acidic soil. Common wisdom holds that growers should maintain a pH range between 5.8 and 6.5 to avoid issues like stunted growth, micronutrient toxicity from excessively low pH, and interveinal chlorosis, or yellowing, from excessively alkaline environments. Although cannabis plants can grow in soil as acidic as pH 5.0 or in neutral soil with a pH of 7.0, maintaining an optimal pH range improves plant health.

Adjusting Feed Charts

The key to adjusting feed charts appropriately to meet an individual plant or garden’s needs is attention to detail. Start by applying the recommended doses of food or fertilizer at appropriate dilutions and keep track of the plants’ responses. This requires keeping a detailed daily journal.

Write down when the plants were fed and what they were fed but don’t stop there. Note any visible responses to the nutrient mixes, including symptoms of nutrient lockout or nutrient deficiency. These two related issues have similar symptoms, including stunted growth, leaf yellowing, and leaf curling.

Unlike nutrient deficiencies, nutrient lockouts occur when plants receive too much food. More specifically, they happen when growers raise the EC level of their soil too high. When the EC is too high, the salt concentration will cause the plants’ cells to shed water and inhibit the uptake of nutrients through the roots.

Dealing with Lockout

Treating, or ideally avoiding, nutrient lockouts may require subtle adjustments to the plants’ feed chart. Growers who feed heavily may also want to flush their gardens periodically by giving them clean, fresh water with no added plant food or fertilizer. At a minimum, growers should flush the excess nutrients from their soil once before switching their plants from the vegetative phase to the flowering phase, once halfway through the flowering period, and once before harvesting the plants.

Addressing Nutrient Deficiencies

Most of the time, nutrient deficiencies can be addressed by very slowly increasing the amount of food or fertilizer given to the plants. Before increasing feedings, try to determine what nutrients are deficient in the soil. If the plant’s unique symptoms could indicate either a deficiency or a lockout, it’s best to flush the soil as a precaution before applying more plant food.

In cases where the plant is deficient in only one type of nutrient, growers may want to switch to a different nutrient blend. Pay attention to the labels, as they offer information on percentages of N, P, K, and sometimes other vital nutrients.

Switching Nutrient Formulas

Feed charts are typically divided into different sections for each stage of growth, but not all plants in all conditions follow these weekly guidelines perfectly. Growers need to pay attention to their plants to determine when the time has come to switch from seedling plant foods to those intended for vegetative growth and when to switch the light schedule to encourage flowering.

Seedling to Vegetative Stage

Cannabis plants typically spend between two and three weeks in the seedling stage. During germination, which occurs prior to the seedling stage, the plants will produce small cotyledon leaves. After 3 weeks, as seedlings, cannabis plants will begin producing small fanleaves.

Apply plant foods, fertilizers, and water in moderation during this early phase to avoid issues with diseases and mold. When the plant begins to develop large fan leaves, it’s entering the vegetative stage.

Vegetative to Flowering Stage

The amount of time plants spend in the vegetative stage is more variable, ranging from anywhere between 3 to 16 weeks. When grown in soil, most plants should spend at least 60 days in the vegetative stage. The flowering phase begins when the light schedule switches to 12/12 light/dark per 24 hour period, or when small white pistils (stigmas) develop near the plant’s nodes.

The Bottom Line

Feed charts are useful tools for novice and experienced growers alike, but they’re only a starting point. Begin by following the food or fertilizer manufacturer’s instructions as accurately as possible, then pay attention to how the plant responds. Growers will learn each strain’s unique needs as the seasons progress. Don’t get discouraged!

Look for signs of nutrient deficiencies and nutrient lockout and take notes every day to make it easier to determine if the plants are receiving the right amount of nutrients. To reduce complications, make sure the plants have been in the vegetative stage for long enough to establish themselves before switching them over to foods or fertilizers designed for the flowering phase.

It’s important to note which strain you’re working with to take note of the different nutrient requirements displayed by separate strains. To get started with some new or classic strains, you’ll want some seeds! For a large online seed bank variety, check out!