a few tips for feeding your garden

a few tips for feeding your garden

Different Types of Cannabis Plant Nutrient DeficienciesGrowing cannabis is a lot of fun until your plants start dying and you ain’t got no clue.

Well, this can be very frustrating, especially if you’ve cared for the plants like they are your pride enjoyment. Among the many problems ailing cannabis plants, nutrient deficiencies are the most common.

It is important to supply your Cannabis plants with the perfect balance of primary and secondary nutrients, as well and trace elements.  As plants mature and enter different stages of their lifecycle, knowing what to feed your plants, when to feed them and why they need that nutrient in the first place can be a huge difference-maker in the overall quality of your crop, including the health and vigor of your autoflowering cultivars.

Lets check the different types of nutrients, signs of deficiencies, and what to consider next time you’re feeding the garden.

Deficiencies of Primary Nutrients 


Nitrogen is an extremely important building block that is responsible for the growth of foliage, hormone, vitamin, enzyme, and chlorophyll production.  Nitrogen is readily available in living soils that have compost present.  Bottled nutrients designed for the vegetative stage will usually have an N-P-K ratio of 5-1-4 in order to keep the available Nitrogen at a preferred level.

If it’s not treated on time, the leaves become yellow and eventually start dropping from the plant.

Signs of Nitrogen Deficiency

•  The fan leaves and surrounding leaves will become a pale yellow color as the stored Nitrogen from the foliage is utilized. The Nitrogen from the leaves will be then used to develop new growth.

•  The tips and edges of the leaf will begin to curl up, at the same time losing vigor and shape.

•  Shortly after the yellow leaf will begin to turn a lifeless brown color.  At this point, the leaf will become dry, curl up and fall off naturally or with the slightest touch.


Very important for seedlings to form a strong root system, the production of photosynthesis, as well as promote heavy blooming once plants enter flowering. Phosphorus is also responsible for resin production and seed production and will usually be found in smaller amounts in living soils or bottle nutrients.  It is after week 4 when a high Phosphorus booster is used in the form of bat guano or as a P-K nutrient.

Leaves and even stems turn purple.  If left untreated, the purple color turns darker and even looks black at times.

Signs of Phosphorus Deficiency

•  There will be brown dots appearing on the biggest leaves first. The leaves will also begin to curl up, similar to the symptoms of heat stress.

•  The brown dots will begin to cover the top half of the leaves, causing the fingers to look dry, dehydrated, and after time begin to curl upwards.


Potassium is used throughout the duration of the plant’s life cycle, for carbohydrate production and most importantly during flowering in combination with Phosphorus.  As both are symbiotic in the role they play for Cannabis plants, maintaining a fine balance is essential especially once flowering has commenced.

The leaves look dull and also burnt at times. They appear rusty and lifeless eventually.

Signs of Potassium Deficiency

•  Similar to a Phosphorus deficiency, signs of rusty brown spots will begin to appear on the surface of the leaves.

•  The leaf tips will begin to turn a pale yellow as more brown coloring begins to take over the rest of the leaf.

•  Over time the leaf will become crispy, curl up, and lose all life.

Deficiencies of Secondary Nutrients 


An essential building block that can be used by the plants in many ways. In the same way we use Calcium to strengthen our bones, teeth, and joints, Cannabis plants use Calcium to hold together cell walls, develop new cell tissue.

Early symptoms show brown spots on the leaves and as it progresses, you’ll see darker spots.

Signs of Calcium Deficiency

•  Leaves and stems will start to become very weak affecting the vigor.

•  Small brown metallic dots will appear on the fingers of the leaves and slowly become brittle and dry.

•  As the tips of leaves curl inwards, the leaf will become a dry, brown color.


As a secondary nutrient, the uptake of Magnesium along with Calcium is extremely important for Cannabis plants. Cultivars such as O.G and Kush are well known for being the first to show signs of Magnesium deficiency and will require more than other strains.  These do very well with supplemental epsom salts.

The veins of the leaves turn yellow from inside and spread to the outer areas of the leaves.

Signs of Magnesium Deficiency

•  Oldest growth will be affected first, meaning the lowest parts will be first to show symptoms, with the new growth being last.

•  Leaves will turn yellow, and there will be a strong contrast of the green veins on the leaf surface.

•  Once the leaf has turned yellow, the tips will turn a rusty brown, become dry, and curl upwards.


Responsible for the production of vitamins, hormones, amino acids, and protein building blocks.  When using aerated compost teas, it is advised to use unsulphured blackstrap molasses.

The leaves turn a bright lime-green in color.  After a while, they appear yellow while the veins also look yellow.

Signs of Sulphur Deficiency

•  New growth will be affected first, causing a discoloration of the leaves.

•  Leaves will turn yellow with dark veins appearing on the surface.

•  Do not get confused with a Nitrogen deficiency as the symptoms are very similar.

Trace Elements Explained

Trace or microelements are used in the smallest amounts by plants, in order to allow them to utilize all of the other available nutrients.

Zinc – Younger leaves will become affected first, with the tips becoming brown and curling upwards.  As the leaves become yellow, there will be a strong presence of veins that become dark yellow.

Copper – Responsible for the role of enzyme production for roots.  The signs of deficiency in Copper are reddish and dark purple hues, usually something seen during the final flush.

Manganese – Very important for the role of photosynthesis and used alongside Nitrogen.  Spots will develop all over the surface of the leaf and may look similar to the rusty brown associated with Magnesium deficiency.

Iron – Another important element for the production of enzymes and aiding in chlorophyll production and photosynthesis.  An iron deficiency will look almost identical to a Magnesium deficiency, so it is vital these two are not confused with one another.

Boron – Helping with the uptake of Calcium and is responsible for cell division.  When there is a lack of Boron, new leaves will become stunted and slow growth.  There will be a pale brown coloration to the inner part of the leaves.

Microelements are used in the smallest amounts by plants, in order to allow them to utilize all of the other available nutrients.

Chlorine – Although this element is often frowned upon for the effects it has on beneficial microorganisms, Chlorine is essential for photosynthesis and cell division.

Cobalt – Aiding in the production of enzymes and responsible for allowing beneficial bacteria to thrive, a Cobalt deficiency causes chlorosis of younger leaves and therefore causing veins.

Molybdenum – Part of enzyme groups that convert nitrate to ammonium.  Not an easy one to spot as the symptoms are very similar to Calcium and Magnesium deficiency.

Silicon – Used to develop the cell walls of the plant, defend against insects, and balance out Iron and Manganese levels.  A lack of silicone will have an effect on the production of leaves, stems, and roots.  It will also cause the plants to have a lower resistance to heat stress and be more at risk of insect attack.

Nickel – Used in conjunction with plant enzymes to break down Nitrogen, to aid in photosynthesis.  Without Nickel, there is an in-balance of urea that can become toxic to the plants.

The takeout

Providing autoflowering Cannabis plants with the right amount of lighting, fresh air, and nutrients is a balancing act.  Knowing what primary nutrients and trace elements your plants need is very important, as well as ensuring they have access to all the necessary elements.

Organic growing mediums are created to fulfill all of Cannabis plants needs, however hydroponics can be far less forgiving.  Checking pH and E.C levels will also have an influence on the way nutrients are utilized by plants.

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