Watering Cannabis: A Step by Step Guide

Watering cannabis is needed to grow healthy and strong plants.


You can also, over water killing your cannabis​—you need to find the balance.

Today we’ll look at watering marijuana and some of the scientific reasons your plant needs specific amounts of water to grow.

We’ll also look at the methods growers use to make the watering process a lot more efficient for both the grower and the plants.

How to Water Your Cannabis

Here is the quick, no-nonsense version:

Time of day to water:

  • Watering earlier in the day allows marijuana to use nutrients more efficiently.
  • Watering at night can promote mold growth.
  • Growing outdoors: Watering early in the morning allows a slower rate of evaporation.
  • Growing indoors: Watering right when the lights are switched on is ideal.

Watering at different stages:

  • Seedlings frequently need small amounts of water—up to 2 times a day if the room temp is high and the humidity is low.
  • Water mature plants once every 2-3 days. Soil should dry out slightly between feedings—just the top layer.

How to prepare your water:

  • Use room temperature water that has been sitting out for 24 hours. This allows the pH to settle giving you a better reading.
  • Adjust to the correct pH: 6.0-6.8 for soil and 5.5-6.0 for soilless mediums.
  • Add your marijuana nutrients to the water. Usually, start by only adding 1/3 - 1/2 of the manufacturers suggested amount and slowly work your way up to full doses.
  • Water your cannabis until there is visible runoff beneath the pots.

No Exact an Science, Yet Important

While the science behind watering your plants is pretty exact, the science behind watering a marijuana plant isn’t quite precise.

Especially since marijuana that grows outside is often left to the mercy of Mother Nature.

There are, however, several principles that we’ll look at here that will help guide your practices in watering.

Factors to Consider When Watering Cannabis

When trying to figure out how much water is enough, and how much is too much, you need to keep these in mind:

Container Size

The containers that your plants are in need to be large enough to have enough space to drink and spread their roots.

If your plants are sitting in a pot or container that won’t hold water, you could be doing your plants a great disservice if they’re not getting the size of drink they need each time you water.

You also need to make sure your container drains well.

As a grower, you’ll have to keep close attention to the container and be prepared to transfer your plants as they grow.

Ideally, you should only transplant once, so make sure to plan ahead.​

Grow Environment

Of course, whether you’re growing indoors or outdoors will have a significant effect on how much you’re watering your plants.

Cannabis plants do like a certain level of humidity, so that should be factored into your water usage as well.

Naturally, if your growing environment is dry and in an area with a lot of sun, you’ll need more water.

In moister environments, it may require less watering.

After growing for awhile, you'll get a feel for how to handle the area you're in.​

Read how you can create the perfect grow environment for your cannabis in our guide on grow tents.

Soil Type

Whether growing indoors our outdoors, the type of soil you’re using to plant your cannabis could determine the water needed.

For instance, soils found in the Western U.S. are more porous than other areas of the U.S., so you’ll need more water to keep the roots of your plant hydrated.

Also, mediums retain water and ​different levels.

Coco coir, peat moss and vermiculite all retain water extremely well.

So, if you're growing in one of these, you'll need to water more frequently, but with less amounts of water.

You can easily drown your plants from over watering or cause root rot in these mediums.​

How Much Water Does Cannabis  Need?

While there is no exact science, and your watering wholly depends the factors mentioned above, a general rule of thumb is to water your plant every 2-3 days.

However, your water needs will depend on your plant and your soil.

There are a few manual ways you can check your plant to see if it needs water:

  • Finger test: You can check your plant’s level of moisturizer simply by sticking your finger into the soil around your plant. If your soil is damp, your plant won’t need any more water. If your soil is dry and crumbly, your plant has used up its supply and will want to be refreshed.
  • Weight test: One method to test your water level in your plants is to know the difference in weight when dry and when watered. You’ll be able to do this either precisely or base your watering on your best assessment of the weight of the plant and pot.
  • Look test: If your plant is thirsty, it’ll look so—an underwatered plant will look lifeless and limp and wilted, which will be hard to miss. You don't ever want it to get this dry, though!

How Much Water is Too Much?

The great thing about the cannabis plant is that it will not drink up any more water than it needs to grow, which seems like a pretty good self-regulating system when it comes to hydration.

This doesn’t mean that you can oversaturate your plant with water.

If you overwater your plant, you run the risk of it retreating, or having its leaves curl up as if they’re hiding, and your plant can grow mold, and other bacteria can fester.

Plus, pests LOVE moist soil.

Letting the top layer dry out in between feedings helps to prevent them from infesting your plants.​

Over-watering your plant can drown it because you’re depriving it of oxygen, which can result in your roots dying.

It’s best to keep your watering cycle consistent and on an as-needed basis.

If you’ve been diligent in testing your water level using the methods above, you shouldn’t water your plant any more than it needs to.

Cannabis Drip Systems

The good news when it comes to watering your cannabis plant, you can choose to use a cannabis drip system that takes the guesswork out of your watering.

This allows you to take the chore of regular watering off your hands.

A drip irrigation system is a common method for green thumbs to raise their plants.

And it isn’t much different for marijuana growers.

Cannabis drip systems, or drip irrigation systems, evenly distribute the water across your plants.

These cannabis automatic watering systems work through using small tubes lined through the bottom of your plants that deliver water at a slow, tiny, yet consistent pace right to the bottom of your plant, where the root can suck it up.

The water delivery system is low-pressure and delivers to the plant only what it needs.

They usually have a feature that allows you to regulate the water pressure as well as use a timing device to get the perfect distribution of water.

Related reading:​

Benefits of a Cannabis Drip System

The benefits of an automatic watering system for cannabis plants can’t be understated.

Here are just a few of the ways a cannabis drip system can improve your growing experience:

  • Low maintenance: If you set up your watering system well, there will be little regular maintenance you’ll have to do each harvest cycle;
  • Efficiency: With a cannabis drip system, you do not use any more water than you need to, resulting in a low water bill and no water waste;
  • Nutrient delivery: Not only can you use your automatic watering system to keep your plants hydrated, but you can also keep marijuana nutrients flowing through the system as well;
  • User-friendly: Although the idea of an irrigation system may sound complicated and intimidating to a new grower, you’d be surprised how easy it is to install one;
  • Budget-friendly: Irrigation systems seem expensive, but depending on the scale you’re looking at, it can be a very affordable option to making your grow system more efficient in the long run.

Where to Get a Cannabis Drip System

When looking at your options for an automatic watering system for your cannabis plants, there are two ways to get one: buy one or make one.

This video reviews the basic materials you’ll require to make an irrigation system for your plants as well as the basic process for installation.

Since the parts that are used to make up the irrigation system are relatively easy to get and cheap, this may be the best option for you if cost is an issue.

Or you can choose to buy a professional system online or at your local hardware store.

Usually, an irrigation system for general use will be sufficient to act as an automatic watering system for your cannabis plant.

A word of advice when you are going to purchase these items, be sure not to indicate that it’s to grow marijuana.

This could cause potential safety issues.


Your garden is YOUR secret, tell no one.

Summing up Watering Cannabis

While keeping in mind that watering your cannabis isn’t an exact science, here’s a summary of the ways that you can stay on top of your watering game:

  • Adjust your watering system based on the grow environment, container size, and type of soil;
  • Understand your plant’s needs by doing a check on your water needs on a regular basis to see how the soil feels, how the leaves look and the overall health of your plant;
  • Know the difference between just enough water, and too much water;
  • Consider your options for cannabis drip systems and how they may make your cannabis watering more efficient;

When setting up your grow room, remember, the way you water your plant is just as important as lighting and nutrients.

Take the time to consider how you’ll provide your plants with the water they need while in the planning stages of your grow room so that you can be sure to implement the most effective system to yield you the perfect bud.

THC Overdose

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