Water – How to Water Marijuana

Watering marijuana plants properly is essential to any grow.  Knowing how to water marijuana and how often you need to be watering marijuana plays a big part on the final buds produced.  With a little bit of knowledge on a few things before you start, like what water actually does, what your water should and shouldn’t contain and how frequently you should be watering marijuana plants, you’ll be growing healthy buds in no time and will avoid learning the hard way.

Why do you water your marijuana?
Your plant uses water as a medium to transport the necessary nutrients it needs to live.  If you use poor quality water which contains lots of impurities, these will be transported into your plant. Generally, if your water is good enough to drink, then it is good enough to use on your plants, but not always!

What are acceptable pH levels?
You want the water you’re using to have a pH as close to neutral (pH 7) as possible as the medium and nutrients you use will affect the pH levels.  Marijuana feeds between a pH of 5.8 and 6.8, which are the levels at which the nutrients are at the most effective.  Outside of these levels, the nutrients can “lock out”, which means your plant is unable to use them and starts to starve.  To make sure your plant can still feed on the nutrients, keep a close eye on the pH levels of both the water and medium.  You’ll find it’s easier and more accurate if you buy a digital pH meter.  If you’re struggling to get your pH to where it should be there are products called pH Up or pH Down, which can be used to bring your pH levels in line and can safely be used alongside any nutrients.

Grow Tip: Always check the pH levels of your water/ nutrient solution and medium before watering your marijuana.  This might seem like a waste of time, but if you have any problems, it’s good to be able to rule out the pH level before looking for more difficult issues to solve.

Grow tip: Tap water changes throughout the year as the seasons change, so keep an eye on the pH before adding any nutrients you may be using.

What’s the best water to use when watering marijuana?

Can I use tap water?Tap water
The simple answer is yes, provided it has a reasonably neutral pH and the correct levels of parts per million (ppm).  Water with more than 140 ppm of total dissolved solids isn’t suitable for use on your marijuana grow as it will interfere with any nutrients you’re using, causing them to lock out or toxify your plant.  If this is the case, we recommend finding another water source, i.e bottled water.  Whether you live in a hard or soft water area will affect any changes you may need to make as hard water can contain too much calcium and lock out other nutrients.   Soft water may require you to add a little calcium (CalMag), especially if your medium or nutrient mix doesn’t contain it.

Distilled water
Some growers hold the belief that using distilled water speeds up your marijuana plants growth.  Whether or not this is true is another matter, but if you’re growing in a hard water area, you may want to consider using distilled water because hard tap water may cause your plants problems as it contains elements that could stop your plant from feeding on other nutrients.  An effective way to purify your water is to bring it to the boil and then let it cool. You can use bottled water from your local supermarket, making sure the bottle is R.O or distilled, otherwise do not use it!  Try to avoid using water that has been carbon Distilled Water filtered as it will not remove the impurities and metals found in tap water.  If you’re serious about using distilled water, the best way to deal with impurities is by using a Reverse-Osmosis machine, which will remove all dissolved solids from your water! It might seem extreme however if you intend to grow on a bigger scale it’s a worthwhile investment.

Grow tip: Chlorine is not bad for your plants and is essential to help process oxygen in photosynthesis.  Most manufacturers of nutrients take the amount of chlorine in tap water into account when making their mixes.  Bear this in mind when watering marijuana plants with distilled or R.O water.

How to water marijuana – How much water do I need?

The size of your marijuana plant, the medium you’re using, and the size of the container all have an effect on the volume required when watering marijuana plants.  A general rule of thumb is to water every other day, but there is a simple way of telling when you should or shouldn’t.  Before watering marijuana plants, tip them to one side, or even pick it up to measure its weight, then water your plant as you would normally and repeat the process.  This enables you to measure the weight it should be and when it needs water.  Your plant will tell you if you are giving it too much or too little water (see below) and it won’t take long to learn when your plants are in need of some H2O.

Grow Tip: The smaller the container, the more frequently you will need to water the plant.

Grow tip:  When watering marijuana plants for the first time, make sure the water is draining out of the bottom of the container.  Allow to soak through and water again after 30 mins as this will enable the moisture to spread throughout the whole medium evenly.

Grow tip: Make sure the medium you are using has good drainage as this will significantly decrease your chances of over watering marijuana plants.  Perlite can be added to your growing medium to increase drainage.

Over watering and under watering your marijuana plants – What to look for.
For the beginner marijuana growers, over and under watering are the most common mistakes.  As plants grow, so does their need for water and nutrients.  As you get used to telling how much water is needed, your plant(s) will give some tell tale signs if it is receiving too much or too little.

Over Watering Marijuana Over watering
Problems it causes?
Over watering your plant drowns the roots by cutting off the supply of oxygen, causing slow growth and increasing the possibility of fungal attacks.  It’s normally the result of poor drainage, and can be avoided by making sure your medium holds a decent amount of oxygen or adding perlite to increase drainage.

What to look out for?
Stunted growth of your plant.
Leaves start to curl down and yellow, but are stiff.
Soil is soggy.

Under Watering MarijuanaUnder watering marijuana
Problems it causes?
Under watering plants is common and can cause roots to die off as they dry out, resulting in slow growth and wilting plants.  It’s more common in smaller containers where a plant needs more frequent watering as it grows.  Pockets of dry soil can also be a cause of under watering so make sure the moisture in your medium is spread evenly by double watering your plant whenever it goes into a new container.

What to look out for?
Stunted growth of your plant.
Leaves will start to curl down and yellow, but will be limp.
Soil is dry to touch.

A basic guide to watering marijuana plants.

Use the following as a basic guide to watering your marijuana plants:

Your water should be around room temperature, ideally 70°F (21°C).  If you’re using water out of the cold tap, allow it to sit and become room temperature before you pour around the base of your plants, otherwise it will put them into shock.   AVOID HOT TAP WATER as this contains more impurities.

Water at the start of your light cycle as this will give your plant a chance to use it straight away, promoting good growth. It will also help avoid any potential for the water to sit and drowned the plants.

Pour water around the base and not over the top of the plants.  If you want to prevent pests through using water, lightly mist your plants at the start of the day when you are watering.  Do NOT MIST your plants once they are FLOWERING as this encourages mold to grow on the buds.

Take pains to avoid getting any water on your light bulbs as this may cause them to explode.

Over watering marijuana plants is a common mistake made by many novice and experienced growers. Knowing how to water marijuana is fundamental if you are going to successfully grow big plump buds.


26 comments on Water – How to Water Marijuana
  1. Vasy

    Hey i want to know when i stop the light i need to leave on the ventiletion and umidification on or off? Please tell me i start 2 week ago and i dont find where i reading about these

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    Rating: -1 (from 11 votes)
  2. Vasy

    Salut am o intrebare…atunci cand se lasa 6 ore fara lumina opresc si umidificatorul si ventilatia ? Helpp

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    Rating: +1 (from 7 votes)
  3. Vasy

    Salut sunt la inceput si nu stiu sigur cand se opreste lumina se lasa ventilatia sa mearga sau trebuie oprite toate?

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    Rating: -1 (from 5 votes)
  4. Justin

    As well my plants r outdoor some are doing hreat from the looks of them and some seem stunted a little bit but thats do to where i put them in the ground but one where the other are doing great seems to smell like mould prettty bad and it kinda looks like its dieing off smells like mould leaves r dieing i dont want it to affect my orher plants how do i stop it did it get to much moisture or something?

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    Rating: -4 (from 6 votes)
  5. Justin

    When do I know when to water my plants some Are doing good some look like they’re not doing good And one is actually smelling like Mould abd is dying off what can I do to stop it please help!!!

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    Rating: -13 (from 17 votes)
  6. Green Man

    Could be your PH and too much phosphorus can block the absorption of iron. So causing deficiency in iron. Or it may have another deficiency in MG or Zn. I would check your PH first.

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    Rating: -2 (from 4 votes)
  7. Jay

    The tips of my leaves Have turned white why is that can anybody tell me please

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    Rating: -4 (from 16 votes)
  8. D

    Super Novice here looking for information. Question is: If I had a few pots on the patio and want to grow some weed. Can you use an automatic watering system to those plants? Do I need to water and mist?

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    Rating: -3 (from 7 votes)
  9. Ernie Head

    Bringing water to a boil and letting it cool is NOT “an effective way to purify water”. It can kill bacteria and other organisms, but the impurities we’re worried about will only become more concentrated from the removal of some of the water.

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    Rating: +6 (from 8 votes)
  10. raven

    My plant has a few leaves that have weird mutations that started early there are small white bumps where the mutations happened and it’s all cemetrical is this a problem I started flowering a week ago and the mutated leaves have started twisting

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    Rating: -3 (from 17 votes)
  11. manuel

    to n.hale im using 5 gallon pots on my grow and under a 1000w light and i give mine a half gallon once a week .And i havent had a problem with it. i do make sure to pour water a little at a time to make sure the soil soaks up the water evenly and to where i can see the water draining out the bottom . i also use a fan to move the air around . im using sugar peak by earth juice and i think it work to good sometime just make sure that you ph your water, the sugar peak will not increase the ph after you have ph;d your water , my plants are about 3 ft tall and about 3 ft round and i use only a half galon of water per week for my 5 gallon pots . i hope this helps anybody else who lookig for info. usually if you follow the directions and the bottles of feed theyll tell you how to use it then its just your judgement on what you are seeing with your grow . if everyone can get a copy of medical growers bible by jorge cervantes it will show you just about eveything you need to know like when you have not enough nutritions when the leaves turn a yellow or spots and diffenticies. sorry for the spelling but grab a copy and you would be amased at eveything in it and will help you understand whats going on with your grow. good luck and have fun keeping it green . peace out

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    Rating: +6 (from 14 votes)
  12. Nenad

    My leafs on 1 of my plants has started to wilt n drup and curl but the top new leaves n shouts are growing fine and my other plant is growing fine can anyone tell me wots wrong or wot im doin wrong? Thanks

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    Rating: -1 (from 7 votes)
  13. Goosed Creeker

    These plants are no different than any other potted plant. They need water.

    The reason plants die from overwatering is not because of oxygen starvation, it is because when the roots are constantly exposed to “swamp” conditions, they rot. Which, I guess, you could say will contribute to oxygen starvation. But, root rot is a direct result of overwatering.

    Watering is not rocket science. When do you water? The answer is simple. Stick your finger in the soil. If it’s dry, it needs water. If it’s still damp, don’t water.

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    Rating: +17 (from 31 votes)
  14. Gareth

    My leafs on 1 of my plants has started to wilt n drup and curl but the top new leaves n shouts are growing fine and my other plant is growing fine can anyone tell me wots wrong or wot im doin wrong? Thanks

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    Rating: +8 (from 58 votes)
  15. Gareth

    Hi ive been told to put A+B into my water is this right? And how much should I be putting in my bucket only holds 10lt thanks

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    Rating: -7 (from 25 votes)
  16. jeremy

    when in the flower should i feed my plants plain h2o between feedings?the nutrient companies feeding charts are saying water with regular water once a month.i think this is a way for the companies to make more money.i also read another guy saying he is water water feed water water feed in pro-mix perlite medium.what should i do?

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    Rating: -2 (from 18 votes)
  17. Green Man

    Unfortunately there is no exact guidelines to follow when watering marijuana plants as there are many different factors that contribute to how much water use. The two main factors are the stage of growth and the medium. When watering seedlings it needs only a very small amount of water compared to when the plant is in flowering stage when it needs larger amounts to ensure it stays healthy. A rule of thumb is that the soil should always be moist to the touch, when the top starts to dry out you know it needs watering.
    The second factor is medium, particularly soil. It’s important soil has good drainage as this will help prevent the roots drowning if the plant is over-watered. The reasons marijuana plants die is because the roots are starved of oxygen when over watered. Mix in perlite to your soil before sowing your seeds as this helps with drainage.

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    Rating: +3 (from 15 votes)
  18. N. Hale

    I see plenty of info on how and when to water but I can’t seem to find it anywhere on how much water to actually use when you do water them. This is crucial information to me as I have just killed a very beautiful plant due to over watering. If I knew exactly how much water to use this wouldn’t have happened. I am using 5 gallon pots and I’m starting from germinated seeds that I will be planting about a 1/2 inch deep in the soil. Please tell me how much water to use and not when or what kind of water to use. I would greatly appreciate the info as this is my 3rd attempt to grow successfully.

    Thank you
    N. Hale

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  19. Green Man

    You should water right up until you flush the plants prior to harvesting. The final flush is essential.

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    Rating: +2 (from 14 votes)
  20. Drinking Distilled Water

    We’re a group of volunteers and starting a new scheme in our community. Your web site offered us with useful information to work on. You have done a formidable job and our whole community can be grateful to you.

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    Rating: +5 (from 9 votes)
  21. Green Man

    It depends on how heavy the rain is really. It would be best to keep them covered/protected. Light rain is fine, a heavy downpour and your seedlings may struggle.

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    Rating: +3 (from 7 votes)
  22. Steve

    Can 2″ to 4″ clones take direct rain, and if so how much?

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    Rating: -1 (from 13 votes)

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