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How often do I water marijuana plants?


by Nebula Haze

If you're growing marijuana in soil or another growing medium like coco coir, you will have to hand-water your plants.

But how often do you water?

Well, you will want to water your marijuana whenever the top of the soil or growing medium starts to feel dry. I like to water when the medium feel dry up to my first knuckle, or about an inch.

Water plants when soil feels dry up to your first knuckle

How to water cannabis properly...

  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 at least 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)

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). It's up to you to decide what's easier for you.

Make Sure Pots Have Enough Drainage

It's very important to make sure 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), 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

  • 16 colas on this cannabis plant - grown in a Smart PotMix 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.

Watering Too Often? 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.

Bigger pots = water less often

Smaller pots = water more often

Speaking of pot size, it is generally best to start young cannabis plants in relatively small containers (like a solo cup with a few holes cut out of the bottom for drainage), 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.

If you started your plants in a solo cup, I'd recommend moving to a bigger pot once the plant is a week or two old.

20-30% Extra Runoff Every Time You Water

Every time you water your plants, make sure that you provide enough water to get about 20-30% 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.

Making sure you keep adding water until you get run-off is also a great way to make sure that your plants are draining properly.

Plus, this practice will immediately alert you to any drainage problems, (as mentioned earlier, cannabis likes well-draining soil) because you'll be able to notice if the water takes a long time to come out the bottom, or doesn't come out at all.

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. 

Drooping 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.

Underwatered Marijuana Plants

  • 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

An underwatered marijuana plant

Learn more about underwatering

 

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

An overwatered Marjuana plant Marijuana Plant drooping due to being overwatered This young over-watered marijuana plant is drooping

Learn more about overwatering

 

If your plant is experiencing "the claw" and not just normal drooping (like the ends of leaves are just pointing down like talons, then you may actually have a nitrogen toxicity (too much nitrogen). 

Nitrogen Toxicity ("The Claw," tips bent down, dark leaves)
Learn more about Nitrogen Toxicity

Nitrogen toxicity - marijuana plant Nitrogen toxic marijuana plant - NOT overwatered

 


 

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