by Nebula Haze
Growing cannabis in coco coir is similar to growing in soil, but also a little different. Considering all the opinions about watering out on the internet, it can be difficult to know how to water plants properly. When exactly do you water plants in coco? How much water do you give them at a time? How often should you give water to your coco plants for the best results? This coco watering tutorial for marijuana aims to take the confusion out of all that!
How Often to Water Cannabis in Coco Coir
Here are some quick guidelines to help you know how to water your plants perfectly every time.
1.) Aim to give water every 1-2 days.
Cannabis plants grown in coco tend to grow the fastest when they’re getting water every 1-2 days, as long as they’re not getting too much water at a time.
2.) Give enough water to get at least 10-20% runoff water out the bottom.
When growing cannabis in coco coir, as a grower you need to provide nutrients in the water. However, nutrients can get built up in the coco if you only give just enough water to wet the medium. By ensuring you get a little runoff water each time, you’re helping make sure that any nutrient build-up gets flushed out, so your plants don’t get nutrient burn and are always getting fresh nutrients in the proper ratios.
To prevent overwatering or nutrient buildup, make sure to always remove runoff water after watering. That way the water doesn’t get sucked back up or start growing things!
A big syringe is a silent way to easily remove runoff water.
As long as a little noise is okay, a wet vacuum is an extremely fast and convenient way to remove runoff water.
3.) If coco is drying out in less than 1 day, here are 5 options.
If your coco is drying out in less than a day, you may need to take action.
5 options if your coco is drying out in less than a day:
- Just water more often – If your plant is healthy and you don’t mind watering your plant all the time, you can continue what you’re doing.
- Give more water at a time – If you’re only getting a little runoff each time, try giving more water at a time. Coco tends to stay wet for longer if you water the plant very thoroughly as opposed to only getting a little runoff out the bottom.
- Transplant to a bigger pot – If you’re getting plenty of runoff water and the containers are still drying out too quickly, you can transplant your plant into a bigger container. With more coco to hold more water, it should dry out much more slowly. However, transplanting can cause stress, especially if the roots get disturbed.
- Break the rule about runoff water – If you can’t transplant, another option is to break the cardinal rule of watering and allow some runoff water to stay in the saucer or tray to act as reservoir. Plants typically stop drinking as much by the second half of the flowering stage, so sometimes if you can hold on, things take care of themselves and you won’t need to do this for long. This isn’t ideal, but sometimes you gotta do what you gotta do. Along the same lines, consider getting an autopot, which hold a reservoir of water, but protects the water from light and uses wicking to ensure roots never just sit in water.
- Put fabric pot inside a hard-sided pot – Another option if plants are in fabric pots, is to put the fabric pots inside a hard-sided pot. This helps hold more water in, since it prevents evaporation from the sides.
Transplant your plant into a new container by digging a hole the size of the original container, and gently placing your plant in the new hole without disturbing the roots at all if possible, like this!
Pat down the soil gently around the plant and give it a good watering!
4.) If coco is taking 3+ days to dry out, give less water at a time until plant starts drinking more.
If your coco is taking a long time to dry out between waterings, chances are you are giving your plant more water than it can drink in a reasonable amount of time. Try giving a little less water at a time until your plant is bigger. Once the coco is drying out more quickly, you can up the amount of water you’re giving until you’re getting 10-20% runoff each time.
Small plants in big containers can take a long time to dry out. Until plants get bigger and start drinking more, you may want to give just a small amount of water at a time in a circle around the plant.
These seedlings were being watered too often, which is why they’re a little droopy. Young plants don’t need a whole lot of water for the first few weeks.
Overwatered cannabis plants in coco.
If you see green stuff growing on the top of your coco (algae) it’s often a sign that you’re watering too often. Although algae won’t hurt your plants directly, it only appears when the top of the coco has been constantly wet for a long time.
These plants ended up getting fungus gnats from being watered too often. The first sign of overwatering was all the green algae growing on the top layer of coco. If you start seeing little bugs buzzing around the soil, it usually means you’ve been giving too much water for a while.
Tips for watering cannabis plants in coco:
- Remember, coco is forgiving – Coco coir is actually pretty forgiving, which is why it can be a good choice for beginners. As long as coco doesn’t dry out completely or get utterly soaked all the time, your cannabis plants will probably be fine.
- AIr pots and fabric pots dry out faster – Plants grown in Air Pots or Smart Pots (fabric pots) typically dry out faster and need to be watered more often than plants grown in containers with hard sides.
- Seedlings only need a little water at a time – Seedlings drink much less water than bigger plants and only need a few cups of water at a time at first. Water seedlings in a circle around the base of the plant, instead of soaking the whole pot.
- Don’t let coco dry all the way out – Plants seem to do better when you avoid letting the coco dry out all the way (as opposed to in soil where plants like to dry out a bit more between waterings). The top of your coco should never appear dusty and dry.
- Don’t let coco be soaking wet all the time – On the flip side, don’t water plants so often that the top of the coco is always completely dark and wet. Watering plants too often can cause the symptoms of overwatering and can sometimes attract fungus gnats or cause algae to grow. It also raises the humidity in the grow space. Higher humidity isn’t a big deal for growers who are starting with dry air, but it can cause problems with mold or bud rot if your environment is getting too humid (above 50% RH), especially in the late flowering stage.
- Too much water is better than too little – I don’t want to encourage overwatering, but if you’re not sure, it’s better to give too much water than not enough. Just don’t go overboard!
How to Know When to Give Water Again
It’s time to give water to your plant in coco when….
- Top appears lighter – The color of the coco has begun to lighten from dark brown to medium brown
- Coco feels cool but not soaking wet – If you touch the coco, it feels cool instead of moist. If the top of the coco actually feels dry, you should definitely give water.
- Container feels light – Most of the weight of your plants is actually the water in the grow medium. That means when the container feels light if you try to lift it gently, it’s time to give more water. Plants in coco with lots of water will feel heavy like there’s a brick inside, but plants in dry coco are much easier to pick up.
- Consider the “napkin method”
- Take a napkin and unfold it so there is only a single ply.
- Press it gently but firmly on top of the coco.
- If you can see the napkin getting wet, give the plants a little more time to dry out.
- If the napkin comes back mostly dry, plants need to be watered.
- Check pictures below – Look at these pictures for examples.
Pictures of Wet Coco (don’t give water yet!) – Dark brown coco, may be growing green algae.
Pictures of Coco Coir That is Ready to be Watered – Medium brown color with some dry spots.
Some growers prefer to water their coco coir every day regardless of how wet the medium is. Coco is a very forgiving growing medium, and it has unique properties that make it really accommodating to roots. For some growers in some setups, this works well, especially in a controlled environment with perfectly sized containers and relatively low humidity in the air. However, for beginners I recommend waiting until the top dries out at least a bit!
Let us know how you water your cannabis plants in coco coir!
