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Tips for Watering Your Cannabis Plants Effectively

Updated 03/25/19

Giving a plant the proper amount of water may be more difficult than you think.

There isn’t an exact science for watering a cannabis plant—you can’t observe the roots (in most cases) and don’t have a way of knowing exactly what’s happening in the soil. Also, a plant is constantly growing and the climate it’s in may fluctuate, so the amount of water it needs will constantly change.

Despite this, here are some tried-and-true tips and strategies to help keep your plants healthy and properly hydrated.

How Often Should You Water Cannabis Plants?

When you think your cannabis plants might be thirsty, take time to observe:

  • Do the leaves look dark green or are they yellowing?
  • Are they vibrant, rigid and strong?
  • How does the soil feel?

A common mistake first-time growers make is to overwater a plant. A healthy cycle of wet and dry is necessary for the roots of a plant to grow out and reach deeper into the pot.

To see if a plant needs watering, stick a finger down a couple inches into the soil. If it’s dry, it’s time to water.

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You can also pick up a pot and feel the weight of it to determine if it needs water. This will take some experience—be sure to lift up your pots after watering to get a feel for how heavy they are when full of water. This will give you a sense of what a light, or dry, plant feels like.

An underwatered plant looks droopy and weak, with yellow or brown leaves. There is no strength in the leaves and they feel lifeless. But an overwatered plant look similar, except that the leaves are dark green and the leaf tips will curl as if they are hiding from the water in their pot.

Obviously you don’t want your plants to ever be in either condition, but as you figure out your cannabis watering schedule, keep in mind that it’s better to underwater plants rather than overwater them.

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Roots pull in oxygen as soil dries and when soil is too wet, the plant essentially can’t breathe.

Pay attention to timing and note the intervals at which you water your plants, and even write it down in a log. But keep in mind that as plants get bigger, they will need more water and need to be watered more frequently.

How Much Should You Water Cannabis Plants?

Holding water rubber hose tube. Watering

The amount of water your plants need will depend on a number of factors, including:

  • Size
  • Outside temperature
  • Overall health
  • Stage of growth

You want to soak the pot and have run off through the drainage holes in the bottom of the pot. Water should pool up on the surface of the soil while you’re watering, but it shouldn’t sit on the surface after you move on to the next plant.

If a plant is very dry, water will run straight through the pot and quickly come out the drainage holes. If this happens, water the plant a little bit and come back to it after 10 minutes or so and water it again, and maybe even a third time. This will allow the soil to slowly absorb water incrementally, until all of the soil is thoroughly wet.

Take notes, make calculations, and get your plants on a watering schedule. Setting a cycle where the plant needs to be watered every two to three days is ideal.

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As the plants grow, so will their need for water. You might need to top-off individual plants in between their full waterings as they grow and you figure out a consistent watering schedule.

The sooner you find the sweet spot between too wet and too dry, the sooner you’ll see your garden flourish.

Is Your Container the Right Size?

cannabis pot

To properly hydrate a cannabis plant, it needs to be in the correct container size. If the pot is too big, the plant can’t drink water where its roots don’t reach. If the roots aren’t absorbing water, water will sit and take a long time to evaporate, which can promote unwanted insects, fungus, and root rot.

Conversely, if a container is too small, the roots won’t be able to stretch out, which will ultimately stunt the growth of the entire plant. You will also need to water the plant all the time, which will add to your labor.

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Ideally, plants should start in a small pot and progress to bigger and bigger pots as it outgrows each container. For example, you can start a clone or seedling in a 4″- or 1-gallon pot, then move on to a 2-gallon, 5-gallon, 10-gallon, and so on.

Plants are ready to transplant when a healthy root structure encompasses most of the soil, but the roots aren’t bound. Transplanting is a good opportunity to see the quality of your roots: bright white roots, with a strong thick structure is a sign you have been watering your plants correctly.

Materials for a Well-Hydrated Cannabis Garden

Large Indoor Marijuana Legal Recreational Commercial Growing Operation

These materials will help optimize your plants and make the watering process easier and more efficient.

Perlite

Perlite comes from obsidian, which is a volcanic glass. It is produced when obsidian is heated to a high temperature and then expands. It’s light, porous, and organic, making it a great addition for your soil, as it prevents soil from clumping and promotes oxygen flow.

Smart Pots

These pots are made with canvas, and the fabric helps roots breathe, allows heat to escape, and lets water drain. All of these traits will improve the quality of your plant roots and how they handle being watered.

Drip lines

Drip irrigation lines allow you to water plants consistently and distribute water evenly across the pot. They also prevent your pots from flooding on the surface when getting watered, which will cause perlite to come to the surface where it is useless. Drip systems also help prevent evaporation when you’re gardening in a hot climate.

Timers

It’s crucial that you measure how much water you are giving your plants. If you have an irrigation system, figure out the flow rate and set a timer so you can gauge when it’s time to move on to the next pot, ensuring every pot is receiving the same amount of water.