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How to grow autoflowering cannabis in coco coir?

Autoflowers especially thrive when grown in coco coir. What is it and how to grow with this best organic medium?
24 November 2019
7 min read
How to grow autoflowering cannabis in coco coir?

  • 1. What exactly is coco coir?
  • 2. How is coco coir better than soil?
  • 3. How to grow autoflowering cannabis in coco coir?
  • 3. a. Break down the peat
  • 3. b. Let the water soak in
  • 3. c. Let the coco coir dry
  • 3. d. Prepare your potting mix
  • 3. e. Use porous containers to pot the plants
  • 3. f. Provide nutrients without fail
  • 3. g. Harvest buds when you wish

If you’re ever wondered how to grow autoflowering cannabis in coco coir, you’re at the right place! Coco coir – termed as the best medium to grow plants, especially cannabis – is not new. For centuries, farmers have used soil to grow a variety of crops, but the technique to grow anything without using soil is definitely new. Lately, the usage of coco coir has gone up, and so has the demand to produce more coir.

All cannabis plants grow perfectly well in coco coir, whether you use nutrients or grow organically. However, autoflowering cannabis strains especially thrive when grown in coir, all thanks to the aeration it provides. Autoflowers have a short lifespan to grow and produce dank buds, so you need to do everything in your capacity to provide the perfect environment meant for them, and that’s where coir comes in.

For those who have no clue about coco coir, let’s first understand how it works...

1. What exactly is coco coir?

Also known as coco peat, coir is made out of coconut husks. The husks are processed and pressed in blocks that can be broken down before you plant seeds or plants in them. These blocks are usually available in most nurseries but you can also buy coir that’s broken down already.


How to grow autoflowering cannabis in coco coir?: coconout

Coco coir is made from coconut husks, making this medium organic and perfect for your garden


If you purchase blocks, you need to immerse them in water until they soak it all and bloat. The blocks break down into small pieces of coir. It’s fibrous, and provides a lot of aeration to the roots, unlike soil that can be a little clumpy at times.

The best way to grow healthy plants is to take care of the roots, and it's super easy to grow autos. In simple terms, healthy roots are equivalent to amazing plants. Thus, since coir keeps the roots happy, the plants ultimately grow well.

2. How is coco coir better than soil?

No limitations – The first thing that comes to mind when you think of growing crops is soil. It’s a common choice. However, it has its own limitations. For instance, soil can easily infect the roots if it’s infected. But, coco peat or coir can be reused without any issues. As mentioned already, coco peat is better than soil if you want to keep the roots happy. Also, autoflowering cannabis varieties grow faster in coco peat, compared to soil. And, that’s because the grower provides all the nutrients that can be used by the plant without any struggle. It’s like getting the benefits of soil and hydroponics at the same time. If you want large, dank buds in a short span of time, growing autoflowers in coco peat will be the best decision you ever made.

pH balanced – Like soil, coco coir is also natural, and contains nothing other than coconut husks. But, growing cannabis in soil can be a pain in the neck, especially when there’s so much to wrap your head around. Think about pH, for example. pH plays a critical role when growing cannabis, especially autoflowering varieties. When you’re growing in soil, pH can be a tad difficult to manage, but coco coir comes with preadjusted EC and pH, making it super easy for growers.

Versatile – Coco peat is extremely versatile and comes with numerous benefits. One can even mix a little soil or just coco by itself. The best way to grow autoflowering cannabis is to mix 70% coir and 30% perlite – an outstanding combination to provide the best environment to the roots.

Eco-friendly and sustainable – Coco coir lasts a long time and is also good for the environment. It doesn’t attract pests unlike soil where dealing with pests is common.

Yield - Although there's not much of a difference in the yield whether you grow in soil or coco coir medium, some growers say that coco coir produces a better yield and you can choose among the top 5 fastest growing autoflowers to produce amazing results. 

3. How to grow autoflowering cannabis in coco coir?

Coco coir or peat is compressed into blocks that can be easily broken down. Step-by-step instructions to use coco coir to grow autoflowering cannabis:

Break down the peat

Purchase a coco coir block. The block comes in different sizes. Depending on your space and the number of autoflowering plants you’re growing, you can get either small or large blocks. Since the blocks come in different shapes and sizes, the total amount of coco coir derived at the end will also differ. For instance, a 5kg block of coir can produce anywhere from 20 to 25ltrs of coir.

Check with your manufacturer and determine the amount of water you can use. It’s safe to go with at least 2-3 times the size of the block, which means that you can immerse a 5kg block in at least 10 to 15 liters of water. Some companies compress blocks a lot more. In this case, even 30 liters of water can be used to break down a 5kg block.

Six Shooter Auto
5 out of 5
I received one seed of this variety as a gift and I can say that this is an excellent quality as always. I think it will be a great product)
Verified customer
Reviewed 9 August 2021

Let the water soak in

Depending on the size and how the coco coir block is processed, it can take anywhere from 1 to 3 hours for the coir to break down completely. Small blocks need just 30 minutes whereas bigger blocks will need more time. Wait until all the coir absorbs all the water. Next, you’ll see the coir bloat right in front of your eyes! To fasten the process, break the blocks into smaller pieces before you begin soaking them, so you don’t have to wait all day.

Let the coco coir dry

If you’re anything like most enthusiastic cannabis growers, you will be tempted to use the coir as soon as it soaks up the water. However, don’t make this mistake. It’s important – nay, critical – to wait until the coir is dry.


How to grow autoflowering cannabis in coco coir?: soil

Make sure your coco coir is properly dry before using it. Keep the lid open to help the water to evaporate faster.


Since coir has the ability to hold water, wet coco coir dripping with water will kill seedlings faster than you can smoke your favorite bud! It may take one more day for all the coir to break down. Most people use a huge drum to let the coir dry, but make sure you keep the lid open so the water evaporates as quickly as possible.

Mexican Airlines Auto
5 out of 5
Really,really one of the Best sativa autoflower that i ever had.Great high,great taste,great yeld.Thanks a lot <br>
F italian.
Verified customer
Reviewed 12 January 2016

Prepare your potting mix

Many people mix coco coir with a bit of soil; however, you can make a potting mix without using soil at all to avoid pests and plant diseases. As mentioned already a 70% mix of coco coir along with a 30% mix of perlite will work fantastically well. If you are keen to add other additives, you can go with:

•  60% coco coir

•  20% perlite

•  10% vermiculite

•  10% soil

However, make note that this mix will be heavier than a simple 70:30 coco coir: perlite because vermiculite and soil can clump the mix.

Gorilla Glue Auto
5 out of 5
first time ever growing and got some amazing colors from this strain with low temps ran it at about 58-64 for 2 weeks and got this color
Jackin Meoff.
Verified customer
Reviewed 26 December 2017

Use porous containers to pot the plants

Once you’ve made the dry potting mix, fill containers up to 3/4th of their capacity. This is because coco coir tends to settle down a bit, and you can add more potting mix as you go. Also, make sure you use containers like smart pots or air pots since they work really well with coco coir. When you use a porous potting mix coupled with containers that allow the roots to breathe, the end result will be fantastic.

Provide nutrients without fail

Coco coir has one disadvantage. It’s a fact that it doesn’t contain any nutrients. However, this can be viewed as an advantage too because you can customize it exactly according to your needs. You will need to provide nutrients from the very first week, unlike soil where nutrients are already present. Agreed, this can be irritating if you’re not very punctual with that. However, if you want a medium that keeps your plant roots happy while delivering huge badass buds, there’s no match to coco coir.

Harvest buds when you wish

There’s no difference between soil and soilless mediums when it comes to the time period required to harvest the buds. Even beginners can grow awesome buds. Once you’re satisfied with the growth, harvest the buds just like you would when growing with soil.

As you can see, it’s pretty easy to grow autoflowering cannabis in coco coir. And, now that you know, you should try it too!

24 November 2019