Growers Guide to Cannabis
Growers Guide to Cannabis - Everything you need to know to grow
healthy roots: higher yields
healthy roots: higher yields
Why do cannabis roots matter?
Maintaining a healthy root system is essential to getting a good yield and lots of sticky buds. Roots are the lifeline of all plants, absorbing oxygen water and nutrients and sending these vital elements up through the plant, to interact with sunlight and be transformed into sugars and energy for growth. A damaged or restricted rootball will be limited in it’s capacity to perform this task well.
Or from the opposite perspective, your cannabis plants can only grow and produce as much as the root system will allow them to.
Unfortunately because roots grow within soil, it’s often the case of “out of sight, out of mind “, and many growers overlook their importance.
Let’s start by understanding what the rootball does.
Functions of the root system:
- Roots are the major source of absorption of water and minerals
- Roots take in nutrients necessary for good growth and are able to store those not used immediately
- The root system anchors plant to the growing medium and stabilizes it
- Roots synthesize cytokin, the hormone controlling vegetative growth but also apical dominance
- Roots can establish a symbiosis with mycorrhiza, fungi which trade accelerated absorption of nutrients for constant access to carbohydrates
Architecture and anatomy:
The first root to develop is called the “radical”. It exists within the seed in an embryonic form and is the first thing to emerge on germination. Once the seed senses that conditions are right for germination, the radical root grows, pushes its way through the seed case and into the soil, seeking water to send up to the developing leaves in order to start the process of photosynthesis. In some strains the radical root evolves into a tap root, a singular major root several feet in length, from which all other roots branch off. In other strains the radical root will die back while the plant is quite young and the root system develops as a dense mass of fine roots (an adventitious fibrous root system) from the base of the stem.
Vertiical roots stabilize and support the Cannabis plant, but their main function is to seek water and nutrients further away in the soil. But it is the network of lateral hair roots which branch horizontally from the vertical roots which will absorb the most nutrients and water.
A healthy root ball will be white, and consist of a mesh of fine horizontal roots growing from many vertical roots.
Damaged roots are restricted as to the amounts of nutrients and water they are able to absorb and transfer upwards through the plant. So how can you tell if the cause of Ill-health is situated under ground?
Signs your cannabis plant is suffering from root stress
- Burnt leaf edges
- Yellowing leaves
- Pinkish leaves
- Brown spots
- Falling leaves
- Curled leaves
- slow growth
- Mixed signs of nutrient problems which don’t respond to adjustments in feeding
- reduction in water uptake
- (Mature plants) droopy stems or leaves. If the roots are unable to absorb sufficient water to meet the plant’s needs your Cannabis will be under watered irrespective of how much water you give it.
- (Young plants) Leaves appear plump but droop downwards. At first glance over watering can be confused with under watering: in both cases the leaves wilt. But in the case of over watering it is that the leaf cells have received water to full capacity, and are weighted down. The chances are though that the leaf cells won’t be able to absorb sufficient water from an over watered soil to reoxygenate the medium. Oxygen is necessary for many root processes including nutrient uptake. Over watering is a particular problem with young plants and small, developing root systems. Cannabis plants with roots sitting in consistently wet soil are likely to develop root rot, be weak and prone to pathogenic infections.
These are all signals which only become apparent once root damage is established and is effecting the upper plant. Experienced and sensitive cannabis growers can spot problems before this. Once they have double checked that the environmentals are within the right ranges, good growers will look at issues with the roots as most probable cause of an unhappy looking plant.
The first thing to do to confirm this diagnosis is to flood the pot with plain pHd water in order to look at the run off. Rotting roots will cause this to be smelly and often discolored. A nutrient buildup will show in the ph and ec reading. If you’re still not sure, carefully remove the plant from it’s pot and examine the root system itself. Bear in mind that any disturbance of the roots will cause a delay in plant development whilst the rootstock heals itself. Tap the outer sides of the pot to loosen the rootball, turn the pot upside down whilst supporting the plant between a V of the fingers of your left hand. Use your right hand to tap the base of the pot and gently shake the contents out. A healthy root system should be white, with a network of fine roots growing from the main ones.
Common causes of root damage in cannabis plants :
- Over fertilization. Also known as “nute burn”. Too strong or too frequent a dosage of nutrients will shrivel roots. Don’t make the mistake of thinking that extra food will be turned into bigger buds, as anything beyond the plant’s natural capacity to absorb is more likely to cause damage. The end result will be less nutrients are taken up and plant growth is reduced.
- Over watering. Too much water in the soil pushes out oxygen and the roots “drown”. This most often happens when young seedlings are kept in pots much larger than the size of the rootball. A newly developing root system can only absorb water in its immediate vicinity: but novice growers will enthusiastically water the entire pot. Best practice is to start off in small (3”/10cm) pots and pot on as the plant grows.
- Insect attack. Root aphids and fungus gnats live in cannabis root balls, damaging them.
disease. There are a number of diseases which can effect the root system but the most common is Pythium. Pythium thrives in warm water and over watered soil. Be ruthless if any plants show symptoms and remove them from your grow room before the disease spreads. - Restricted pot size. A too-small pot restricts root growth and limits the overall growth of your cannabis plant. Signs that your cannabis plants are root bound include frequent wilting, stunted growth, yellowing leaves, new leaves are smaller, and there are signs of nutrient deficiencies.
- Temperature: roots are much more sensitive to temperature extremes than the actual plant. Cannabis can cope with an occasional drop or rise but if the root system experiences either cold or heat there will be a negative impact on overall plant development.
- Poor drainage, either from the pot itself or due to a claggy medium. Roots sit in wet soil with low oxygen levels.
- Incorrect Ph of the water. Ph determines what elements can be absorbed by the roots. Read more about the importance of ph here.
How to treat cannabis root problems
- Identify the probable cause. Luckily most issues become obvious once you have diagnosed root development disorder.
- Tackle the cause:
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- maintain a healthy happy temperature (read why grow room temps are important)
- avoid under/over watering (the wet/dry cycle)
- Treat insect attacks with the appropriate pesticides. An effective way of dealing with gnats is to hang yellow sticky traps. These are harmless to your cannabis plants but will attract and kill flying adult insects such as gnats, white fly and aphids. At around $12 for 20 strips, we suggest using them in an indoor grow room as a preventative measure.
- keep plants in the appropriate pot size
- maintain a good climate control in your grow room. If growing outside insulate pots at night in cold weather and raise off the ground in hot sun (this enables air to circulate and prevents baking the root ball.
- check the temperature of the water ESPECIALLY in a hydroponic set up. Warm water holds less oxygen and diseases flourish (see water temperature ranges in a hydroponic system
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The skill of being able to diagnose and remedy a root issue is a useful tool for any cannabis cultivator, but its obviously better to avoid problems in the first place .
How to promote healthy root growth
Give young plants the best start:
Cannabis is most vulnerable during the first three weeks. Seedlings and clones are dependent upon the developing root system to send water up through the stem for use in photosynthesis as the plants use light to convert carbon dioxide and water into the sugars necessary for growth.
Promoting vigorous root development at this stage results in larger plants which are healthier, more resistant to pests and diseases, and which will produce bigger yields.
Avoid the temptation of feeding young plants.
Use a neutral soil, specially designed for seedlings. When you do start to add feeds to the water, start off at 1/80 of standard veg stage strength. Avoid overwatering.
DO NOT FEED YOUNG CANNABIS SEEDLINGS
Just as an egg is packed with the energy to enable the chick to break free through the shell, so does a seed contain sufficient nutrients for the seedling to develop the primary roots and it’s first leaves. Adding feeds at this stage overloads the delicate developing roots and leads to nutrition burn and long lasting damage.
Read more about cannabis seedling care here
Use a cannabis root stimulator
This may seem contradictory to the statement above, but whilst we advise against giving young marijuana plants nutrients, you will find that using a root stimulator for cannabis seedlings has huge impact on the plant’s potential.
What are root stimulators?
Cannabis root stimulators contain macronutrients which enable seedlings to develop an enhanced primary root system capable of supporting vigorous vegetative growth and excellent nutrient absorption.
Giving seedlings even a diluted vegetative feed risks more damage than it benefits. A seedling/ clone root stimulator reduces the problem of over feeding and also yellowing leaves with reduced photosynthesis. Other stimulators are designed to promote vigorous growth throughout the life cycle of the plant.
Every brand of cannabis nutrients is likely to provide a root stimulator. Key factors to look for are:
- Multiple vitamins
- Enhance disease resistance
- natural ingredients
- Suitable for use beyond seedling stage
- easily absorbed
What is the best root stimulator?
I’m going to get honest here. To be frank, I think that all the major brands perform more or less equally and I suspect that some new nutrient producers may perform better, at least with their launch product. Which one you use will come down to personal preference and the strains you grow. Some root stimulators stand out though:
Smart Pots Soft-Sided Container, with Cut handles
$2.99
Soft-sided fabric aeration container that has the rigidity to hold its shape
Provides aeration, enhancing root structure, resulting in a vigorous plant with more flowers and fruits and increased insect and disease resistance
Allows excess heat to escape
Melonfarm 3/5/7/10/15/20 Gallon 5-Pack Grow Bags /Aeration Fabric Pots w/Handles for Plant Growth
$12.00 $10.49
SUPERIORITY: MELONFARM Aeration Fabric Pots Allow Roots to Breathe and Grow Healthier, Boosts Plant Growth and Yields.
USE FABRIC: Made with High Quality Nonwoven Fabric, Built-in Handles for Easy Movement.
EASY TO CLEAN: Wear-Resisting,Highly Tear Resistant,Easy to Clean,Can be Used Repeatedly.
Grow Bags, Fabric Pots, 5-Pack Plantmate Flower Plant Hydroponic Fabric Planter with Handles
$7.90
Aeration: Breathable fabric grow bag allows aeration for your roots and allows soil to cool better on hot days.
Healthy Roots: Fabric prevents harmful root circling and promotes healthy root pruning.
Easy Relocation: Handles make for safe and easy transportation when your plant is ready for transplant.
Hydrofarm RC1 1 Gallon Smart Pot
$1.99
Take advantage of the benefits of traditional plastic gardening containers while eliminating the shortcomings
Soft growing containers
Keeps the root system from overheating on hot days
Smart Pot Soft-Sided Fabric Garden Plant Container Aeration Planter Pots, 1 gallon, 5 Pack, Black
$14.74
High quality plants grow in less time
Roots stay cooler during hot weather
Reusable, inexpensive, light weight, attractive and simple design
Smart Pot Soft-Sided Fabric Garden Plant Container Aeration Planter Pots, 5 gallon, 5 Pack, Black
$34.99 $22.72
High quality plants grow in less time
Roots stay cooler during hot weather
Reusable, inexpensive, light weight, attractive and simple design
Smart Pot Soft-Sided Fabric Garden Plant Container Aeration Planter Pots, 3 gallon, 5 Pack, Black
$30.99 $18.67
High quality plants grow in less time
Roots stay cooler during hot weather
Reusable, inexpensive, light weight, attractive and simple design
Superoots Air-Pot 5 Gallon Equivalent Garden Propagation Pot Planter Container
$20.95
5 Gallon Equivalent pot
Eliminates root circling
Reduces growing time in the garden
Provide enough Oxygen.
Yes, plants produce oxygen through photosynthesis, but roots don’t photosynthesize: instead they gain energy for growth through cellular respiration – and for this they use oxygen.
The texture of the grow medium determines the amount of oxygen available to the root system. A heavy clay soil retains water and has hardly any space for oxygen.
If you are growing in pots, we recommend using a “light mix” soil or coco and perlite, possibly the best medium for retaining oxygen around the roots.
if you are growing weed outside, then it’s good practice to improve aeration of the ground before planting. For centuries gardeners have prepared soil through a mixture of adding improvers such as bark, manure, straw and grass climbing with the technique of digging over (which breaks up slabs of dirt into smaller pieces). Modern growers can choose to use a nutrient neutral perlite or coco instead.
Understand the principle of the wet/dry cycle :
Always let the soil dry before watering as this enables oxygen to be pulled down through the earth.
TOP TIP: SUPER CHARGE THE NUTRIENT SOLUTION
Adding 1 pint of hydrogen peroxide to 1 gallon of water, shake vigorously for 30 seconds and let settle for 12 hours increases the amount of oxygen by up to 30%
Bubblers kick start healthy root growth
Easy to make, bubblers use the principle of aeroponics to maximize root growth. Basically just a bucket with an air pump, and filled with a weak nutrient solution, bubblers deliver high levels of oxygen, water and nutrients directly to the root system. You can use a bubbler bucket with several small 2” net pots as a propagation system to produce young plants with super root systems which will accelerate veg growth whatever medium you pot onto. Alternatively, a 5 gallon bucket will sustain a fully mature 5 foot plant through flowering.
How to make your own bubbler
- 2 x 5 gallon buckets with lids. Thoroughly clean, then clean again using hydrogen peroxide (H2O2) which destroys harmful elements and evaporates after 24 hours, leaving no harmful residue
- either 1 x 6” net pot or up to 12 x 2” net pots
- in the center of the lid cut a 6” hole (or slightly smaller) so that the pot sits in snuggly. If using the bubbler to bring on small plants then evenly arrange the pots
- make a 2cm hole close to the rim of the lid. This is for the air pump hose
- With lid in place, wrap the bubble bucket with black gaffer tape or paint with black waterproof paint. If light gets to the nutrient solution harmful algae’s bloom
- Connect an air-stone to an air pump and place in the bucket. Thread the hosing through the small hole in the lid and hang the pump on the grow room wall.
- we suggest putting seeds / clones in Rockwool and using clay pebbles to stabilize this within the pot
- Use the second bucket to mix your nutrient solution. Don’t forget to adjust pH
- fill the bubbler with the Nutes to the point where the net pot just touches the water
- put on air pump for 24 hours a day
- check daily to see how much water has been used. Let the solution level drop to an inch below the pot before refilling.
Bubbler buckets use a type of hydroponics called Deep Water Solution (DWC).
Bloom Brothers Cloner Bucket
We were amazed by the accelerated root growth that formed when we used one of these aeroponic cloning buckets. Actually I couldn't help lifting the plants out twice daily just to go "wow! look at the roots"! ...
If you want to get your cannabis plants off to a great start, this is an affordable and definitely recommended way to do it
Additional images:
Price: $99.95
Maintain a good rootball temperature.
Cannabis plants – like many other plants – can withstand extremes of temperature outside the optimal ranges as long as the root system itself doesn’t experience heat shock. This is why spring bulbs may flower despite an unusual snowfall. However if your marijuana plants experience sustained extreme heat ranges, then your grow medium may become too hot or too cold for the roots to process minerals properly.
In an indoor grow room, the solution is to maintain a good climate control.
Monitor the temperature of your nutrient solution: as water warms, the level of oxygen falls. Read “water temps in hydro”.
If you live in an area where summer temps are high but like to grow cannabis hydroponically then you should weigh up the cost of a water chiller against the loss of not growing through the hottest months.
If your weed is growing outdoors, there are some precautions you can take:
- insulate pots/soil level against cold temperatures by wrapping with bubblewrap/cardboard to protect against cold snaps.
- reduce reflected heat in pots during hot weather by standing pots on inverted crates/pallets to allow airflow underneath the pot. Choose white pots instead of black.
Air pruning and how it stimulates a more productive root ball
Traditionally gardeners use the method of “potting on”. Young plants are started off in small pots and transplanted into a slightly bigger size as the rootball outgrows the existing one. This occurs several times until the cannabis plant is in its final stage pot. The practice of potting on is a sound one. If you put a cannabis seedling directly into a large pot, the ratio of root mass to soil would be so unequal that the roots would be unable to absorb moisture and water would stagnate at the bottom of the pot. (See causes of root problems above)
But potting on has its disadvantages. Calibrating the period when it is time to move on to the next size pot risks the plant becoming root bound. In the short term this isn’t a problem as long as the roots receive sufficient nutrients and water to support plant growth. Left just too long however and optimum vegetative growth is restricted (see above). The major drawback to this method is transplant shock . This is sustained by the marijuana plant every time it is moved into the next pot, and each time development is paused while the plant recovers.
Temporary periods of being root bound and recovering from transplanting only minimally effect overall vegetative growth and ultimate yields. Many weed growers see them as inevitable hesitations in plant progression.
Air pruning eliminates these issues and at the same time triggers increased root growth with improved complexity. Every time a root tip comes into contact with air it prunes itself and creates a double tip, each new shoot growing back through the soil. Air pruning becomes an almost constant process with the result that root mass can be as much as 5 times larger than marijuana grown traditionally. Increased root mass is augmented by the fact that this technique creates a root ball made up of numerous fine lateral roots able to soak up higher levels of nutrients to be used by the plant.
Air pruning is therefore a technique which really optimizes plant development. But the best thing is that air pruning requires no advanced skills. All you have to do is buy the right pots and the plants will air prune themselves!
Smart Pot Soft-Sided Fabric Garden Plant Container Aeration Planter Pots, 2 gallon, 5 Pack, Black
High quality plants grow in less time
Roots stay cooler during hot weather
Reusable, inexpensive, light weight, attractive and simple design
Additional images:
Price: $23.99 $18.15
Superoots Air-Pot 5 Gallon Equivalent Garden Propagation Pot Planter Container
5 Gallon Equivalent pot
Eliminates root circling
Reduces growing time in the garden
Additional images:
Price: $20.95
Give your cannabis the nutrients necessary for root growth
Phosphorus and potassium encourage plants to put out new root shoots and help to strengthen existing roots as they continue to develop. That’s why even though cannabis needs a feed high in nitrogen for leaf growth, a vegetative feed also needs to contain phosphorus and potassium. Some outdoor weed growers don’t bother with veg nutrients, but if the ground is not naturally rich in these chemicals root growth – and therefore plant growth, will be restrained.
Beneficial Microorganisms
A healthy organic soil contains many bacteria and fungi which are beneficial to root growth and disease resistance. These microorganisms have a symbiotic relationship with the roots, and can be used by cannabis cultivators to improve overall yields.
Mycorrhizae (Fungi)
Mycorrhizae attach themselves to the plant roots and grow deeper into the soil. Independent of the plant, they increase its capacity to absorb nutrients in exchange for sugars secreted by the roots.
Trichoderma (Fungi)
Trichoderma are a group of fungi that form a natural defense against root damaging pathogenic fungi.
Beneficial Bacteria
As with beneficial fungi, bacteria can be added to the soil or medium to break down organic matter, facilitate nutrient uptake, and add protection against pathogens.
The larger the population of beneficial bacteria, the quicker they can destroy pathogenic microorganisms and/or break down organic matter. As with mycorrhizae, it is safe to say that if the soil has a bountiful population of beneficial bacteria, it is more likely to have a healthy root system.
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