Watering Cannabis Plants

All plants, including marijuana, consist of about 80% water. Therefore it makes sense that issues with the water management could cause damage to the marijuana plant. Ourdoors in the ground, the marijuana plant usually has enough soil to work with. Depending on the quality and the structure of the soil, it also helps to regulate the amount of moisture. With indoor cannabis cultivation in pots it’s highly likely that the plant gets too much or too little water. The risks indoors are a lot greater, that why watering of the marijuana plants  needs to happen with the greatest knowledge and care.

How often do you give your cannabis water?

Well, you will want to water your marijuana whenever the top of the soil or growing medium starts to feel dry.

  1. Wait until the top of the growing medium is dry about an inch deep (up to your first knuckle – just use your finger to poke a hole in the soil and see if it feels dry).

  2. Add water until you see 10-20% extra runoff water drain out the bottom of your pot. Go back to step 1. Note: If water takes a long time to come out the bottom, or if pots take longer than 5 days to dry out before the next watering, you may actually have a problem with drainage (more info below).

If you’re growing in super soil or another heavily amended potting mix, you won’t be adding extra nutrients to the water during your grow. As a result, your plants will have to get all their nutrients directly from the soil. In that case, you want to avoid giving enough water that you get runoff, because runoff water will carry away some of the nutrients in the soil. Watering until you get runoff is important when using liquid nutrients because it helps prevent nutrient build up, but with super soil it’s better to give just enough water that you wet the entire medium but don’t get extra water coming out the bottom.

Some growers also use the “lift the pot” method to decide when to water your plants (basically wait until your pot feels “light” since the plants have used up all the water).


Removing runoff water is a great start to make sure you’re watering your cannabis plants perfectly, but it’s also important to make sure pots have enough drainage. It’s very important that water can drain freely from the bottom of the pot, otherwise the plant can get waterlogged and become overwatered (causing the plant to droop).

In addition to making sure the actual container has drainage (holes on the bottom, or some other way for extra water to escape), it’s also important to make sure your growing medium drains freely. If it takes several minutes for water to come out the bottom of your pot when you water, it means that there isn’t enough drainage in the actual growing medium (it’s too dense, so water is having a hard time getting through).

How to improve the drainage of your growing medium

  • Mix in extra perlite to loosen the soil and allow water to drain through more easily.
  • Never add bark or wood chips! They are not good for growing cannabis plants. On that note, never use soil for growing cannabis that contains bark or wood chips. If growing cannabis in soil, the best soil to start with is composted super soil.
  • Use Smart pots – these fabric pots help get oxygen to your roots (which gives you faster growth) and this type of pot makes it much, much harder to overwater your plants. A cannabis plant growing in a tan fabric smart pot is pictured to the right.
  • Another simple way of increasing the oxygen and decreasing the amount of moisture in any soil-based growing medium is to poke holes into the soil with a pen or pencil. This will allow the soil to aerate (have more oxygen).

Watering Too Often? Or Barely at All?

In the beginning of your grow, you will likely be watering your marijuana plants every week or couple of days. Watering every 3-5 days is optimal. As your plants grow bigger, you will watering them more often unless you move them into bigger pots.  If you feel like you are watering your plants too often, you can move them into a bigger pot so that it holds water for longer, a cannabis plant will be drinking a lot as she approaches harvest time. It is generally best to start young cannabis plants in relatively small containers, and only move plants into bigger containers as they get bigger. Starting in smaller containers makes it a lot harder to overwater your plants when they’re young, and makes it easier to flush plants and/or respond to problems if they occur.

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Every time you water your plants, make sure that you provide enough water to get about 10-20% extra run-off out the bottom of the container, especially if you’re feeding additional nutrients in the water. The reason for this is that sometimes soil and soilles growing mediums like coco coir start to form natural salts if it the fertilizers just sit in there and never get washed out. These built-up salts can eventually cause nutrient problems, pH problems, and nutrient lock-out if they’re not rinsed out.

If You’re Providing Extra Nutrients In The Water…

First, make sure you’re using proper cannabis nutrients for your growing medium. They should be formulated for a plant like tomatoes, and they should have a different feeding schedule for the Vegetative (Grow) and Flowering (Bloom) stage. It’s generally a good idea to feed your cannabis plants with nutrients every other watering (at most) and provide plain, pH’ed water the rest of the time. This will greatly help reduce the amount of salt buildup and prevent nutrition problems from occuring.

Underwatered Marijuana Plants

If your cannabis plants shows signs of drooping, chances are you are over or under-watering. In order to prevent over or under-watering, make sure you water thoroughly every time (don’t just water a tiny spot in the middle of the pot, you should be getting 20-30% extra runoff water every time), and wait to water again until the top inch of the growing medium feels dry, up to your first knuckle or so.

  • Wilting is the first sign of underwaterd marijuana plants
  • Leaves are limp and lifeless, they may seem dry or even “crispy”
  • Will eventually lead to plant death if not corrected

Overwatered Marijuana Plants

  • Drooping / Curling is the first sign of overwaterd marijuana plants
  • Leaves are firm and curled down all the way from the stem to the leaf
  • Will eventually lead to leaf yellowing and other signs of nutrient problems if not corrected

Cannabis plants are like any other plant: they can handle some overwatering and some underwatering, so take your time in figuring out its ideal watering schedule. The sooner you find the sweet spot, the sooner you’ll watch your garden flourish.



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