Welcome to our guide on how to grow cannabis in coco.
In this guide, we will discuss the basics of growing cannabis in coco, what to feed your plants, and how often. How to fix plant problems, and what caused them.
This guide will give you a good understanding of what coco is, how to grow in it, and why it is such a great medium for growing cannabis.
Coco, sometimes called Coco Coir, is a grow medium, used for growing many plants, not just cannabis. It consists of the fibres and outer shell of coconuts.
Though it May Look Like Soil, Coco is Not Soil!
Unlike soils, coco comes with no nutrients in the medium. You will add your own.
This will give you complete control over what is available to your plants
Because coco is void of nutrients, it needs to be treated before it can be used for growing cannabis.
Most companies will treat their coco, before they bag it up. Sometimes, the coco will come as a compressed brick, which will expand when water is added.
The best coco will come in bags. This coco would most likely have been treated before it was sent it to the consumer, and you will be ready to grow in it after rinsing it. Put it into pots, and flush it through with some water at the correct PH level, and you're ready to grow.
Coco that comes in a compressed brick, will be dehydrated, and may not have been treated properly. You will need to add water to the brick to expand the coco, and then, treat it to ensure it doesn't leach nutrients when the plant needs them. We will go into more detail later on.
Though there are many brands of coco you can buy, there is one brand that always stands out as number one. That brand is CANNA.
CANNA has been making coco, and nutrients for decades, and most growers will use them. Even companies who make nutrients, will use CANNA coco for their tests. They are a long standing reliable source of coco for growers.
Their coco is also very cheap! And can be reused over and over again if treated properly.
You can buy bags and bricks of CANNA coco, so you can choose what is best for you. Both the bags and bricks of coco have been treated and are ready for use in growing. You just have to rinse the coco, and flush it through with pH'd water.
If the coco you're going to use hasn't been treated, you will need to soak it in a nutrient solution that is high in calcium before using it.
This takes a guide of its own, and is only necessary for untreated coco. The coco you buy, will probably be ready to grow in, but it if does need treating, then see our guide in the Coco Section of the site.
If you have bought good coco, you can go ahead and put it straight into your pots.
Mix up some water ( 3x times your pot size), and adjust the pH of it to 5.8. Add a small amount of nutrients, pour it through the coco, and remove run off.
This will bring the medium to the ideal pH range, and offer a seedling some nutrients when the tap roots grow.
There are two main types of plant nutrients, salt based nutrients, and organics. Though you can use either one for growing cannabis is coco, it is highly recommended you go for salt based nutrients.
Salt based nutrients are also known as synthetic, or chemical nutrients. These nutrients have a longer shelf life, and are immediately available to your plant once they are in the medium.
As long as the pH of the medium is in the correct range, using salt based nutrients will make feeding your plants easy, and you will see less deficiencies and excess throughout the grow. And even if you do get problems, they are easily fixable.
Salt based nutrients are not environmentally friendly. They have been known to cause damage to the environment if not disposed of correctly.
Organic nutrients are made from broken down living material, and organisms. These nutrients are chemical free, and a lot more environmentally friendly than salt based nutrients.
When a plant is fed with organic nutrients, the minerals it needs are not immediately available to the plant. Bacteria in the medium needs to break down these molecules, before the plant can use it.
Because coco will dry out a lot quicker than soil, keeping a good level of microbes in the medium can be difficult. Making it harder to grow organically.
If you would like to use coco to grow organically, than consider a soil like mix, where coco is mixed with peat moss, and other ingredients to make a soil.
Hydroponics is growing cannabis in anything other than a soil based medium. Air matters a lot, to the way a cannabis plant can eat. Light mediums like coco, or rock wool, can bring a lot of air to the root zone, which will allow the plant to eat more, and drink more.
In full hydroponics setups, air stones are used in pools of water to give the plants even more air to the roots. This is one of the reasons why cannabis plants in hydro grow quicker.
Coco is like a middle ground between soil and hydro. It is a firm base for your plant to hold onto with its roots, but it has good air to water ratio in the medium.
Soils will be more compact, and hold on to water for a lot longer. They may also be treated with limes and other pH buffers to help keep the pH level.
Coco, is just coco fibres, with nothing added, so the pH will need to be altered and held at the correct levels for optimal nutrient uptake.
In all hydroponics systems, the pH of the medium should be kept at 5.8, during flower it can swing between 5.8 and 6.2. This includes coco.
If the pH of the medium is off balance, the plant cannot absorb the correct nutrients. Most cannabis plant problems when growing in coco are caused by the pH of the medium.
To monitor the pH of the medium, you need to monitor two things:
1: The pH of the nutrient solutions going in
2: The pH of the runoff
Always feed at pH of 5.8 in veg, and 6.0 in flower. When testing the run off, the pH needs to come out in between 5.8 and 6.2.
You need to ensure your readings are accurate. For this, you will need a good reliable pH meter. Essentials and Blue lab are highly recommended amongst the growing community. You can buy them from amazon here:
If the pH is rising or falling below the optimal levels, you may have a salt build up. This is caused by over feeding the plant, and the EC of your nutrient solution has been too high.
When you use salt based nutrients for growing cannabis, you can measure the electroconductivity of the water you have added your nutrients to. The more salts dissolved in your water, the higher the EC will be.
If you are using tap water, then the chances are your water already has minerals and salts dissolved into it, and has an EC reading. This is known as your "Background EC" (BGEC).
The background EC is counted towards your overall EC, as this is still available to your plant when it is in the medium.
Plants at different stages of growth will need different levels of EC. But most growers will rarely exceed 1.4, even for huge plants.
There is also TDS, and PPM, which can be used to measure the salt content of a solution. But the most reliable methods, and most widely used, is EC. Get a good reliable EC meter, along with a good PH pen, and you're set to grow healthy cannabis in coco.
Coco is light, and airy, and has the ability to draw lots of air into the root zone. The more air the root zone can get, the more it can process nutrients and drink more water.
To accommodate for this, it is a good idea to use either fabric, or "Air Pots" for your cannabis grows.
Rather than having solid plastic pots, which can only draw fresh air in through the top of the medium, and a few holes in the bottom, a fabric or smart pot, can draw air in through the sides too.
Air pots are designed in a way to encourage "air pruning" of the roots. This will make more roots grow throughout the medium, and stop your plant becoming root bound.
Fabric pots will be the cheaper alternative, but for the best investment, go for Air Pots:
Start seedlings and cuttings in small pots around half a litre in volume. As the plant grows bigger, it will need more root space.
During early veg, you should have your plants in pots around 3L in size. You can transplant again if you are going to veg your plant for over 6 weeks, into a 10-12L pot.
Flowering Cannabis plants will rarely be in anything smaller than 12L pots, and nothing bigger than 25L.
On average, plants will be finished in pots between 12 and 15L in volume.
For a full guide on what pots are best for what mediums. See our guide here:
The roots of a cannabis plant are the most important part of its structure. The roots will anchor the plants into the ground, and provide it with the vast majority of its nutrients.
To keep the root zone fresh and healthy, it needs to have a good supply of air running through it. If there is a lack of fresh air, bad bacteria can form, and start to cause damage to your root zone, which will cause problems across the whole plant.
By using Air Pots, or Fabric pots, you will deliver more air to the root zone, but there can still be problems. Always remove run off after feeding your plants, over watering can suffocate your roots, even if you have good drainage.
Some growers will like to add perlite to their coco to improve the drainage. Coco already has good drainage, but perlite can be used if you're going to feed your cannabis plant more than once a day.
Perlite will increase the drainage of the medium, so water will pass through quicker. This will allow the roots to get plenty of air before the next feed, which in some setups, is only 15 minutes away.
With good drainage, comes lots of runoff. Every time you feed your plants, you will need to get at least 10% run off back out of the pots. And this can lead to a lot of water being left over.
Try and have your pots raised off the ground, so you can direct run off from the trays into a bucket or container. Removing runoff can become a real chore over time, especially if you're feeding daily. Take this into consideration when you set up your grow room.
Raised trays, on a slight slope, that run off into a bucket is the easiest way. But you can use a water pump, or even a wet vacuum to remove it. It just has to be removed!
Though the feeding schedule will differ slightly in the early stages of growth, for most of the grow, your plants will be fed daily.
In the early stages of the seedling stage, and when the plants are transplanted, watering less will encourage the roots to grow more.
Some growers like to push it to water every other day, but most prefer a daily feed, or even numerous times a day.
When coco dries out, some of the salts from the previous feeds are left behind. Lots of air can get to the root zone when growing in coco, so a lot of water will evaporate.
As water evaporates, salts are left behind. This can cause an EC spike, and may cause nutrient burn and excess in your plants.
By feeding often, you can keep the medium, and the root zone at optimal levels, and offer more consistency to the plants.
Hand watering is cheap, and easy, but time consuming, especially if you are watering your plants daily.
A fully flowering cannabis plant in coco, can easily drink 3L of water a day, every day. You will need 2 buckets or containers that can hold enough water to mix your feed. One bucket for todays water, and one bucket for tomorrow ( water from the tap should stand for 24 hours to "degas").
After you have mixed the food, and the pH and EC are at the ideal levels, water your plants slowly. Let the water make its way through the medium, don't force it by pushing too much water through it at once.
You can use a jug, a watering can, a bottle, whatever makes it easy for you, it just has to be clean.
Because it is hard to over water cannabis plants grown in coco, you can use auto feeding systems to water them numerous times a day.
A water pump is placed into your nutrient solution, and is set on a timer. The pump will pump the water out for a set amount of time to water the plants. Run off is usually collected and added back into to the reservoir for a recirculating system
Though this makes watering your plants very easy, it does come with other issues. The reservoir will need adjustment to the correct pH and EC regularly, and it will need topping up every few days.
You will also need air stones running for 24 hours a day to keep the oxygen content of the water at a decent level.
Reservoirs should be cleaned every ten to fourteen days to prevent the build up of algae and fungus.
Automated systems will add to energy costs, noise, and heat in the grow room.
They are a double edge sword, if you have the time to hand water daily, take that route, if not, an automated system might be your best option.
When you water your cannabis plants in coco, you are adding new salts to the medium, and removing old, used ones. Everytime you feed/ water your plant, it is to restore the medium to ideal levels, and keep them there.
The only way to remove these old salts from the medium, is by washing them out. This should be done every time you feed them.
With at least 10% run off, you can ensure that most of the old salts have been washed out of the medium, but you need to remove this run off, and drain it away from the pots.
You can't leave your plant to sit in the run off. As the water evaporates from your trays, the salts will be left behind. If your roots are in contact with this, they will be absorbing a nutrient solution that is way too strong for them.
Also, sitting in water will restrict the flow of air to the root zone. If plants are left to sit in run off for too long too often, your plant may begin to suffer with root rot, or insects such as fungus gnats might find a home in your pots.
Runoff can be checked, and monitored, to follow if your plant is being over or under fed. This can help diagnose plant deficiencies.
One of the best things about growing cannabis in coco, is how quickly plant problems can be fixed. You can flush the medium and restore balance within an hour, and see improvements within a day.
When you learn how to grow cannabis in coco, you will find that routine is your friend. If you stay consistent with what you give your plant, you will:
A: See less problems throughout the grow
B: Diagnose a problem faster if you have one
The number one cause of cannabis plant problems when growing in coco is pH problems. If the pH of the medium is off balance, the plant can not use the nutrients available to it.
It does not matter what is in the medium, if the pH is off, the plants diet will be affected. PH imbalances are usually caused by salt build up from overfeeding. It is important to monitor your run off to make sure the levels are staying in range.
Always feed your plant at the correct pH ( 5.8-6.2). Then, with ten percent runoff, the medium will be reset to 5.8 with every feed. Check the pH of the run off, it should be within 5.8-6.2 pH, if not, you will need help from our cannabis growers forum.
A cannabis plant deficiency is when you plant isn't getting enough a particular element it needs for growth. This can happen for two reasons:
Deficiencies caused by lack
of nutrients in
Deficiencies caused by an
imbalance in pH in
Each deficiency will show particular symptoms. By correcting the pH of the medium, and raising the EC, a deficiency can be fixed quickly. Here are some picture guides to help you:
Over feeding a cannabis plant is the second most common cause for cannabis plant problems. Second only to pH imbalances, which are caused by excessive feeding.
Many growers will think, the more they can feed the plant the better. This is a misunderstanding, the plant will only eat what it wants, you can't force it to eat more.
You can only provide what it needs as it needs it. Forcing a plant to eat will cause problems, and may actually stop the plant from eating.
When a cannabis plant is over feed for too long, not enough run off is collected, or runoff isn't removed, the roots can get blocked by salts in the medium.
This will stop your plant from eating and drinking. Because of this, excess may show as signs of deficiency. It is important to monitor the EC of your run off to know if the salts are building up.
If your run off EC comes out much higher than the EC of your feed, you have a salt build upcoming, or has already taken place. The medium needs to be flushed thoroughly to remove all of the excess salts. Then you need to refeed your plants, at a lower EC, and give it some time to repair.
There are two reasons for flushing your cannabis plants in coco, to remove a salt build up, or to remove nutrients for pre harvest flush. Both are the same, but if you are harvesting, you will no longer feed your plant after the flush.
If your are flushing to remove salt build up, or restore balance to the medium, you should alway refeed the plants. Don't let your plants sit in coco that has no nutrients in it. This will cause your plants to leach nutrients from itself and put it into the root zone via osmosis.
To flush your plants in coco, simply prepare 3x as much water, as you have pot volume. For example, 10L pots = 30L of water.
Balance this water at 5.8 pH, and flush it through the medium, collecting and draining all run off. For an in depth guide on flushing cannabis plants, see our guide here:
Flushing your medium and restoring balance will fix most problems within 24 hours.
If you need any help with a sick cannabis plant, or have any questions about how to grow cannabis in coco, you can always sign up to our forum and ask for help from experienced cannabis growers.
Now you know how to grow cannabis in coco, we will quickly run through each stage of the life cycle, so you understand what to expect.
Start off in small pots around 0.5L in volume for a couple of weeks. Feed a very low EC of around 0.2-0.4 points over your BG EC.
You don't need to water daily at this stage, every other day, or even once every 3 days is fine. Less water will encourage the roots to grow longer in search for it.
Do not let the pots dry out, that is very bad for the roots and the root zone.
As the plant grows, follow the run off, and watch the plant for signs of deficiency. Gradually increase the EC of your nutrient solution as the plant allows, but go no higher than 0.6-0.8 points over your BG EC, you do not want to over feed them.
The demand for a higher EC will come as the plant grows bigger, but do not force it to eat more, just monitor you plant, and raise the EC when it is needed.
Before flipping the plants to flower, you should transplant them into their final pots. After a week in their new pots, change the light cycle and induce flowering.
During the stretch, your plants will be in high demand of nitrogen, feed them "grow" nutrients, during this stage. Only raise the EC if the runoff is coming out lower then the feed going in at this stage. Do not over feed!
With the formation of flowers, comes the need for a different diet. You will reduce the amount of nitrogen available to your plant by switching to "Bloom" food.
During the flowering stage, plants will need a higher dose of potassium and phosphorus, and using a PK booster here is recommended.
When your plant has ripened, check your trichomes. If you see between 90-100% milky trichomes, then you should begin you 2 week flush.
You will flush your plants with 3x water, as you have coco in your pots. Then water them normally ( with no nutrients just water) for the next 10-14 days until harvest.
10-14 days is prefered, as this will reduce the amount of salts in your plant matter and bring out the best in the terpenes.
After a good long flush, the plant will begin to turn yellow, and leaves will begin to fall off. Break off a leaf, and taste the liquid coming out of the stem. If it is bitter, you need to flush longer, if it tastes
like water, you can harvest.
For an indepth look at the life cycle of a cannabis plant, check here:
Coco is seen as one of the best mediums for growing many types of plants, not just cannabis. It makes things much easier, especially for beginner growers.
Growing in coco might take up more time than growing in soil, as you have to water more often, but problems are easier to fix, and you have more control over the plants diet, so problems will arise less often.
If you're looking to start your first grow, coco is what is recommended.
Thanks for reading! You can find more information on anything related to growing in our cannabis grow guides. All of our guides are written by experienced growers, and members of our cannabis growers forum. If you have any questions, sign up. It is free, and we are always happy to help!
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