Automatic Drip Irrigation Setup for Indoor Cannabis Grow

All you need to know to get your irrigation system ready to go!
31 August 2021
9 min read
Automatic Drip Irrigation Setup for Indoor Cannabis Grow

Contents:
  • 1. How does automatic irrigation work?
  • 2. The components of an irrigation system
  • 3. Irrigation options
  • 3. a. Drip rings
  • 3. b. Individual drippers
  • 4. Setting up your automatic irrigation system
  • 4. a. Setting up drip rings
  • 4. b. Setting up drippers
  • 5. Adjusting water flow
  • 6. In conclusion

An automatic irrigation system may seem like a hard task but it doesn't require any skill and can help you save time and effort when growing cannabis indoors. Obviously, buying an irrigation system can be expensive but if you make yours from scratch it’s just as easy and far cheaper. An automatic irrigation setup allows you to water multiple times a day without manually turning on or supervising your equipment, saving you time and effort. So read along if you want to learn how to build your own cannabis automatic irrigation system!

1. How Does Automatic Irrigation Work?

An automatic irrigation system consists of a large water reservoir that is usually placed outside the grow tent, this water reservoir has a water pump inside which is plugged on a timer. The water pump sends water through one main water tube into the grow tent, where it’s then distributed to the cannabis plants. Some growers also buy or make draining saucers which drain to a bucket outside the tent, allowing you to remove run-off water without having to raise each pot individually.

 

Automatic Drip Irrigation Setup for Indoor Cannabis Grow: Cannabis plants in pots

An example of automatic irrigation setup.
 

This is basically how an automatic irrigation system works, obviously, there are several different ways to do so, depending on your grow setup, number of plants and your personal preferences but, in most cases, here’s what you need to buy or build your own automatic irrigation system.

2. The Components Of An Irrigation System

As mentioned, there are several ways of making an automated irrigation system so you can build it however you want as long as it has the following components.

Water Reservoir

The water reservoir is one of the most important elements of an automatic irrigation system because it stores water. When choosing the reservoir, you can use a barrel, bucket or even a tub, as long as it can hold water there shouldn't be a problem at all. But, there are a  couple of things you should have in mind, they are:

  • Reservoir size: a 120x120cm grow tent can use up to 12 liters of water a day so make sure you do the math and know exactly the size of the reservoir. Have in mind that you want to have a reservoir that can hold enough water for your irrigation system to run for at least 3-4 days. 
  • Height: when talking about reservoir height, you want to get a reservoir that’s taller than the tips of the tubing that goes on top of the pots, this will cause gravity to pull water down and avoid water pressure-related problems.
  • Color: avoid clear plastic or white reservoirs because the water or nutrient solution should be protected from sunlight as much as possible. When possible, go for dark blue or black reservoirs.

Water Pump

The pump needed to water your plants automatically shouldn’t be too big but it needs to have enough power to pull water into your grow tent and have enough pressure so that water gets distributed to all plants equally. If you’re growing less than 10 plants, you can go for an 1100 L/h pump, which should be the minimum for any automatic irrigation setup.

If you’re making an irrigation system for more than 10 plants, you can estimate around 200 L/h per plant, this way you can determine how large the water pump should be. Also, have in mind that it’s recommended you have 8 - 10 cannabis plants per water pump because having more than 10 plants for one single water pump can make it hard to balance water distribution, meaning that some plants will get more water than the others so if you’re growing more than 10 plants make sure you make two irrigation systems with two separate water pumps.

Timer

Most growers use analog timers but they only allow you to turn on or off every 15 minutes, so in order for you to establish the watering intervals, you need a digital timer with one second intervals, this allows you to fine-tune your irrigation system down to the second.

 

Automatic Drip Irrigation Setup for Indoor Cannabis Grow: Necessary materials

Essential compounds to set up your own automatic irrigation system.

Oxygenation

It’s vital you keep water or nutrient solution in the water reservoir oxygenated, this helps prevent harmful bacteria and also helps oxygenate the substrate. If you’re using water reservoirs up to 120 liters, you can use regular air pumps and air-stones to oxygenate the water or nutrient solution inside but if you’re using larger reservoirs, you should use a stirring pump to mix and keep the nutrient solution oxygenated.

Digital Thermometer

You need a simple digital aquarium thermometer to keep the nutrient solution’s temperature in the acceptable range. It’s vital you keep the temperature between 18 - 20 °C to prevent harmful bacteria and maintain the dissolved oxygen.

Main Water Line

The main water line is what transfers water from the reservoir, into the tent, and to the plants. For the main water line you can use any type of tubing, although using poly tubing is recommended due to being more resistant, semi-rigid, and easily found in black. Obviously, anything works. As long as you can transfer water from outside the tent to your plants, you can use whatever you want to.

3. Irrigation Options

Once you have everything mentioned before ready, you have to choose how you’ll be irrigating your plants. There are a lot of different ways but most are similar to the following: Individual drippers or drip rings, both work very well but have their pros and cons. Drip rings are considered superior because they do not leave dry spots in the substrate but you cannot move them after they’ve been placed, so they can only be used in the final containers.

Irrigation Methods Pros and Cons

Irrigation setupProsCons
Drip ringsSaturates all the substrate equallyCannot be moved
Individual drippersCan be moved as you pleaseCan leave dry spots in substrate

 

On the other hand, drippers are much more flexible, so you can have a dripper on a small pot and continue using the same dripper as you transplant to bigger pots, but the downside is that drippers usually leave some parts of the substrate dry if you don’t plan it properly and you’ll end with a lot of plastic tubes all over your grow tent.

Drip Rings

Drip rings are probably the best option if you’re planting in the final container because they improve water distribution and can eliminate eventual hand-watering. In order to install drip rings you’ll need:

  • 15 cm or 22 cm drip rings: if you’re growing in 20-liter pots or less, you should go for 12 cm drip rings. If you’re growing in 20-liter pots or larger, go for the 22cm drip rings instead.
  • 1.2 cm Tubing: almost all drip rings require 1.2 cm tubing to connect the drip rings to the main water line, but make sure to always measure the tubing and connectors before buying them.
  • Connectors: they are needed to connect the tubing that goes from the drip rings to the main water line. Sometimes it can be hard to connect the tubing to the connectors so it's recommended you dip the tip of the tubing in hot water in order to make it more flexible and easier to attach it to the connectors.
  • Ball valves: ball valves are small valves that connect to the tubing and allow you to control water flow to each individual drip ring. These are not always needed when using individual drippers but are essential to adjust water flow when using drip rings.

Individual Drippers

Individual drippers offer more flexibility because they’re not fixated on the substrate but they don’t distribute water as effectively. In most cases, when using drippers you will have to hand-water 1 to 2 times a week in order to keep the substrate saturated properly. In order to install individual drippers, you’ll need:

  • End Cap: The end cap goes into the end of the main water line this prevents water from coming out the end of the tube and forces it to run through the tubes that water each plant.
  • 0.6 cm Tubing: This smaller tubing goes attached to the main water line and brings water to each individual cannabis plant. This tubing size is needed when using 1 or 2 tubes per plant but you can use bigger or smaller size tubing, depending on what you want to achieve.

 

Automatic Drip Irrigation Setup for Indoor Cannabis Grow: Second set of materials

Everything you need for an automatic irrigation setup.
 

  • Pierce Connectors: In order to attach the tubing mentioned above to the main water line, there are several ways but the best option is to use pierce connectors. This type of connector is super easy to use, you just have to pierce the main water line and then attach the tubing to the fittings and that’s it.
  • Drippers: In-line drippers go at the end of the 0.6 cm tubing and are what distribute the water around the pot. Installing them is super easy, just slip the tubing on the drippers and you're done.

4. Setting Up Your Automatic Irrigation System

Setting up an automatic irrigation system is super easy, you don’t even need special knowledge, all you need are scissors, and a drill or something with a sharp tip to make the holes on the water reservoir for the tubing to pass through.

First of all, you need to prepare the water reservoir so drill a hole on the side of the reservoir, make sure to make the hole according to the size of the tubing you’re using; The tubing should exit the reservoir near the top edge (as high as possible) so that water can flow easily and water drains back into the reservoir when irrigation stops.

 

Automatic Drip Irrigation Setup for Indoor Cannabis Grow: Reservoir setup infographic

How to set up your automatic irrigation system.
 

Once you’re done with the hole, place the water pump, airstone, and thermometer in the reservoir and cut a hole in the lid to be able to pass the thermometer probe, the water pump’s power cord and the air pump tubing.

You’ll also have to make sure the main water line enters into the tent at the top of the pots, so you have to make a hole in your grow tent for the main water line to enter. Once you have the main water line in the tent, you have two options: Either drip rings or individual drippers, so here’s how to assemble both of the irrigation methods.

Setting Up Drip Rings

Setting up any type of irrigation system can be tricky if it’s your first time doing it but fortunately, is quite simple. All you have to do is measure the length of the tubing you need and use scissors to cut them to the right size. Once you have everything ready it’s just a matter of sliding the tubing onto the connectors and then attaching the drip rings.

 

Automatic Drip Irrigation Setup for Indoor Cannabis Grow: Drip rings infographic

An example of automatic irrigation system with drip rings.

Setting Up Drippers

If you’re installing drippers, use the pierce connectors to pierce the main water line and install the drippers. It’s a good idea to place the empty pots just to give you an idea of where to install the drippers. If you feel like the tubing is too long, just use a pair of scissors to cut a piece and then try again until everything is in place.

Automatic Drip Irrigation Setup for Indoor Cannabis Grow: Drip emmiter infographic

An example of automatic irrigation system with drippers.

5. Adjusting Water Flow

After installing the drippers or drip rings you need to run the irrigation system to adjust water flow for each plant. So, right after installing it, turn the irrigation system on and close the ball valves or drippers, and turn on the water pump. After turning on the pump, open each dripper or ball valve slowly until water comes out slowly and evenly.

After starting your grow cycle, you may notice your plants are getting too much water or not enough water, so wait until your system is running again and continue adjusting water flow. Your objective is to dial in every irrigation until all plants produce the same runoff at the same time.

Once all drippers or drip rings are watering with the same amount of water, you have to adjust each irrigation so your plants get enough water to produce around 10% of run-off.

“Depending on where you’re growing, you may want to look into self-draining saucers so you don’t have to lift the pots to remove the water after each irrigation.”

It’s impossible to say exactly how long each irrigation should last, so it’s a matter of trial and error. Each irrigation should be long enough to produce at least 10-15% run-off from each plant. Most growers water for 35 seconds with drip rings and up to 2 minutes with individual drippers, but this varies according to the substrate and growing conditions. So make sure you know exactly how much water each plant gets so you know exactly when the irrigation system should turn off, this will help you schedule irrigations.

6. In Conclusion

Building your own automatic irrigation system may seem like a hard task but it’s actually really simple. You can make your own irrigation system with cheap and easy-to-find components. An automatic irrigation system allows you to travel for a couple of days or just keep your plants fed when you’re busy, saving you time and effort. 

 

If you use an automatic irrigation setup in your indoor grow space, feel free to share your tips with fellow growers in the comment section below!

31 August 2021
Comments