Fertilizer guide
There are so many different ways to fertilize your cannabis plants.
We have broken it down into three ways. Pick a method below, or scroll to the bottom of the page to learn about the 17 essential elements like Nitrogen, Phosphorus and Potassium.
Each method boils down to delivering the essential nutrients the plant needs.
Method
Organic
Amend the soil once, then just water. No mixing, no daily pH checks.
Method
Salt based
Mix nutrients into water every feeding for fast, precise control.
Method
Hybrid
Salt based fertigation blended with organic amendments and biologicals.
Organic, step by step
- Mix amendments into your soil before planting. Blend dry amendments or compost into your growing medium (soil) at the product's recommended rate.
- Leave a buffer zone. Keep a pocket of seed starting soil where you'll plant your seedling, so young roots aren't sitting against concentrated nutrients.
- Water only. Once your plant is in the ground or a pot, water whenever the top inch of soil dries out. The soil does the feeding from here.
- Top dress in flower. When buds start forming, scratch in bloom specific amendments to the top of the soil and water them in.
Why it works
Organic fertilizer feeds the microbes in your soil, and those microbes release nutrients to the plant slowly over time. No pH adjusting, no measuring EC. Many growers report more complex flavor and aroma from organic grows.
Products we recommend
A good starting point is Nature's Living Soil Organic Concentrate paired with Girl Flower Power. Great organic compost works well too.
Browse the fertilizer section on our growing gear page →Want more detailed advice for your specific setup? Call or text us at 919-410-6945, we're happy to help.
Salt based, step by step
- Mix nutrients into water. Follow the product's feeding chart. Start at half strength for seedlings and young plants.
- Check EC. Use an EC meter to measure nutrient concentration, and write it down so you stay consistent from feeding to feeding.
- Adjust pH. After mixing, check pH and adjust with pH up or down as needed.
- Feed with every watering. Most salt based growers feed nutrients at every watering rather than alternating with plain water.
pH targets
Salt based fertilizer feeds the plant directly through the roots. Nutrients are immediately available, so you get a faster response and precise control if something is off, and salt based feeding typically leads to larger yields.
Products we recommend
A good starting point is General Hydroponics Maxi Grow, Maxi Bloom, and Kool Bloom, along with pH Up and pH Down to keep your feed in range.
Browse the fertilizer section on our growing gear page →Want more detailed advice for your specific setup? Call or text us at 919-410-6945, we're happy to help.
Hybrid, step by step
- Start with a salt based fertigation program as your base, following the same mixing, EC, and pH steps as the salt based method.
- Layer in organic amendments to the growing medium for slow released nutrition and long term soil health.
- Add foliar applications to support the plant directly, alongside the root feeding program.
- Choose a substrate that holds water and nutrients, like a soil or coco blend, rather than a fully inert medium such as rockwool, so biological life in the root zone has something to work with.
Why growers try it
Blending mineral nutrients with organic inputs and biologicals aims for the yield and consistency of salt based feeding alongside the flavor and resilience organic growers report. It takes more attention than either method alone.
Products we recommend
Start with a salt base like the General Hydroponics line, then layer in organic amendments on top.
Browse the fertilizer section on our growing gear page →Want more detailed advice for your specific setup? Call or text us at 919-410-6945, we're happy to help.
This is a more complex program, and we don't recommend it for new growers.
The elements
Seventeen essential elements. Every feeding method exists to deliver these.
Three come from air and water. The rest have to come from the soil, or from you. Size roughly tracks how much of each a plant actually needs. Tap any element to see what it does and what it looks like when a plant runs short.
Primary macronutrient
Nitrogen
Role
Drives vegetative growth and is the core building block of chlorophyll and every plant protein.
Deficiency sign
Older, lower leaves turn pale yellow first and growth slows.
Not sure what you're seeing on your own plant? Call or text us at 919-410-6945 and we'll help you figure it out.
Tap an element above to read about it
Read the full list of all 17 elements
- Carbon (Structural)
- Makes up roughly half of the plant's dry weight, the backbone of every sugar, protein, and structural tissue. Deficiency sign: practically never deficient, the plant pulls it straight from the air.
- Hydrogen (Structural)
- Provides the electrons and bonds that hold plant sugars and water together. Deficiency sign: never deficient in a normally watered plant.
- Oxygen (Structural)
- Used in respiration to convert stored sugars into usable energy. Deficiency sign: shows up as root problems in waterlogged, oxygen starved soil, not as a nutrient deficiency.
- Nitrogen (Primary macronutrient)
- Drives vegetative growth and is the core building block of chlorophyll and every plant protein. Deficiency sign: older, lower leaves turn pale yellow first and growth slows.
- Potassium (Primary macronutrient)
- Regulates water movement, enzyme activity, and overall plant vigor. Deficiency sign: leaf edges yellow and curl, then brown and go crisp at the margins.
- Phosphorus (Primary macronutrient)
- Fuels energy transfer, root development, and flower formation. Deficiency sign: leaves develop a dark blue green or purplish tint, especially on the underside.
- Calcium (Secondary macronutrient)
- Builds strong cell walls and helps new growth develop properly. Deficiency sign: new leaves come in twisted, stunted, or spotted with brown.
- Sulfur (Secondary macronutrient)
- A building block of amino acids and several plant enzymes. Deficiency sign: younger leaves turn uniformly pale yellow, unlike nitrogen deficiency, which hits older leaves first.
- Magnesium (Secondary macronutrient)
- Sits at the center of every chlorophyll molecule, essential to photosynthesis. Deficiency sign: yellowing appears between the veins of older leaves while the veins stay green.
- Iron (Micronutrient)
- Needed to build chlorophyll and keep enzyme systems running. Deficiency sign: yellowing between the veins on new growth, often mistaken for a magnesium issue.
- Manganese (Micronutrient)
- Supports photosynthesis and helps activate several enzymes. Deficiency sign: fine yellow mottling between veins on newer leaves.
- Zinc (Micronutrient)
- Involved in growth hormone production and enzyme function. Deficiency sign: new growth comes in small, narrow, and closely bunched together.
- Boron (Micronutrient)
- Helps build cell walls and supports flower development. Deficiency sign: growing tips become brittle, distorted, or die back entirely.
- Copper (Micronutrient)
- Supports enzyme activity involved in growth and reproduction. Deficiency sign: new leaves wilt or take on a dark, twisted appearance.
- Molybdenum (Micronutrient)
- Needed in tiny amounts to help the plant convert nitrogen into usable forms. Deficiency sign: older leaves develop pale, mottled patches between the veins.
- Chlorine (Micronutrient)
- Involved in water regulation and photosynthesis. Deficiency sign: rare, but shows up as wilting and bronze colored leaves.
- Nickel (Micronutrient)
- Needed in trace amounts for the plant to process nitrogen waste products. Deficiency sign: extremely rare, can cause leaf tip dieback in severe cases.
Common questions
Answers to the questions we hear most about how to fertilize cannabis
What is the best fertilizer for cannabis?
There is no single best fertilizer, it depends on what you want out of your grow. Organic feeding is the simplest and most forgiving, and tends to produce more flavorful flower. Salt based feeding gives you the fastest control and feedback if something goes wrong, and typically leads to larger yields. A hybrid approach blends both for growers chasing the most out of every plant, but takes more attention to run well. If you are not sure which fits you, start with organic, it has the least room to go wrong.
What fertilizer should a new grower use?
Organic feeding. It removes the two most common new grower mistakes, overfeeding and pH swings, by taking them out of your hands entirely. You mix amendments into the soil once before planting, then just water. A good starting point is Nature's Living Soil Organic Concentrate paired with Girl Flower Power for the flowering stage.
What products does Triangle Seeds recommend for salt based feeding?
A good starting point is General Hydroponics Maxi Grow, Maxi Bloom, and Kool Bloom, along with pH Up and pH Down to keep your feed solution in range. Salt based feeding also requires a pH meter and an EC meter, since you are measuring and adjusting your nutrient solution at every watering.
What is the Synganic hybrid approach to fertilizing cannabis?
It blends a salt based fertigation program as the base with organic amendments layered on top, aiming for the consistency of salt based feeding alongside the flavor and resilience organic growers report. It is the most involved of the three methods and requires more attention to run well, so we do not recommend it for new growers.
What nutrients does a cannabis plant actually need?
Seventeen essential elements in total. Three, carbon, hydrogen, and oxygen, come from air and water. The rest have to come from the soil or from what you feed the plant, split into primary macronutrients needed in the largest amounts (nitrogen, phosphorus, potassium), secondary macronutrients (calcium, magnesium, sulfur), and micronutrients needed only in trace amounts (iron, manganese, zinc, boron, copper, molybdenum, chlorine, nickel).
What does a nutrient deficiency look like on a cannabis plant?
It depends on the nutrient. Common signs include yellowing that starts on older, lower leaves and moves up the plant, yellowing between the veins while the veins stay green, leaf edges browning and curling, or new growth coming in small and distorted. If you are not sure what you are seeing on your own plant, call or text us and we will help you figure it out.
Do I need to flush cannabis before harvest?
Flushing has not actually been proven necessary, and plenty of growers skip it entirely. If you do choose to flush, don't cut nutrients out completely. Keep feeding some calcium through the last stretch, since stripping out all nutrients late in flower can weaken stem and cell wall strength and raise the risk of bud rot.
