How to water a cannabis plant

A person with a waterdrop on his finger above the pot with cannabis seedlings

Cannabis is generally a resilient plant, and most strains can tolerate mistakes with feeding and watering to some extent. However, consistently delivering water and nutrients in the wrong concentrations or quantities can cause deep-rooted problems that can prove detrimental—or even fatal—to your crop.

Cannabis plants need abundant water, particularly in the flowering stage. As a general rule, plants should never be deprived of water for too long at any stage of their life cycle, as this can severely slow or even halt growth entirely. As well as this, depriving plants of water deprives them of nutrients, which not only slows growth but can lead to deficiencies.

Over-watered cannabis plant with grey mould

Moderation is key

However, over-watering is a mistake many new growers make. Over-watering can lead to pythium (root rot), botrytis (grey mould) and powdery mildew, as well as causing nutrient toxicity and anaerobic (oxygenless) soil conditions in extreme cases. These issues can be disastrous, and are often extremely difficult for newbies to correct.

Most growers agree that soil should be allowed to dry out slightly between feeds—this lessens the risk of rot, mould and nutrient burn, and may also encourage the roots to grow denser. However, plants should always be watered before the roots start to dry out.

Finding the right balance is crucial, and it varies according to the strain (tropical sativas may be remarkably thirsty, while many indica strains abhor damp) and the size and growth stage of the plant—as well as other factors such as choice of medium.

When should cannabis plants be watered?

There is some controversy over the best time of day to water cannabis plants. Most growers believe that cannabis should be watered at night time, but some argue that they should be watered earlier in the day.

Those that believe cannabis plants should be watered at night argue that in a natural environment, precipitation does not fall when the sun is shining, due to cloud cover. Many also state that if water droplets resting on the leaves are exposed to heat and bright light, they may act as “magnifying glasses” and burn the leaves.

It appears that this is just a myth, although leaf burn can occur through prolonged contact with some fertilisers. In any case, possible issues can be avoided altogether if care is taken to simply direct the water towards the soil and not the leaves!

A cannabis plant growing outdoor against the Sun and the blue sky in the background

On the other hand, watering earlier in the daytime allows the plant to utilise the available nutrients more effectively, as many of the fundamental processes of plant growth occur in sunlight. Leaving soil damp throughout the cooler hours of night can promote mould growth.

If growing outdoors, watering in the morning rather than the warmer afternoon appears to be optimal, as the rate of evaporation is slower. If growing indoors, watering at around the time lights are switched on may be preferable—while temperatures rise quickly with “hot” lights such as HPS, it usually takes some time for them to peak.

How often should cannabis plants be watered?

At first, young plants will require small amounts of water at frequent intervals—up to twice per day if room temperatures are high and relative humidity is low. As they mature, they may be fed less frequently with greater quantities. Typically, large flowering plants must be fed at least once every 2-3 days.

The correct time to water plants should become apparent upon testing the moisture level of the growing medium. It should feel dry on top, but still somewhat damp below the surface. If it remains dry to the touch at depths of more than 5cm or so, plants are probably too dry.

Cannabis plants growing in the yard with other plants

This may all vary widely according to the drainage properties of the medium. For example, coco typically requires daily watering at first, then twice-daily as the plants increase in size; this is due to the fact that it retains water extremely well, so giving too much at once can saturate the medium and reduce airflow.

With experience, a visual check or simply testing the weight of the container will aid in determining when to feed, as a dry container obviously weighs substantially less than one full of water.

A step-by-step guide to watering cannabis plants

First, prepare your equipment. You will need a source of water, a pH meter, pH down (this could be any strong acid), your chosen nutrients, and a watering can, hose or similar.

Water should be around room temperature—hot or cold water can shock and stress plants severely and sometimes irreparably. Most agree that water should be left to stand for 24 hours before use as this allows pH to be more accurately determined.

pH should be between 6.0-6.5 if growing in soil; if growing in soilless medium this value may be somewhat lower (coco prefers the 5.5-6.0 range). Use pH down to reduce pH if necessary, making sure to mix well. Incorrect pH can result in nutrient burn and various deficiencies, as roots are unable to process nutrients as effectively.

An analog and a digital pH meter in a plastic transparent watering can

Add nutrients according to the manufacturer’s instructions, and mix thoroughly. Nutrient concentrations may be adjusted according to the strain and the stage of growth of the plant—such as when plants are young, or just after being transplanted.

Using a watering can, hose or similar, water the plants until runoff is visible in the trays beneath the pots. Many growers aim for around 10-20% of total water draining off, as this is believed to prevent nutrient build-up—but this is disputed.

Nutrient build-up occurs due to oversupply of nutrients (or reduced uptake by the roots due to overwatering or pH issues), and is fixable by flushing with pure water and not by adding more nutrient solution.

This basic guide should give novice growers all they need to successfully water and feed cannabis plants. However, adjustments to the basic principles may need to be made according to local climate, choice of strain, type of medium, and several other factors.

  • Disclaimer:
    Laws and regulations regarding cannabis cultivation differ from country to country. Sensi Seeds therefore strongly advises you to check your local laws and regulations. Do not act in conflict with the law.

Comments

82 thoughts on “How to water a cannabis plant”

  1. Hardwood furniture possesses one thing extremely organic regarding it.
    There is feeling of warmth, of
    attributes as well as of beauty that can easily be be located in wood
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    earth.

    1. How high are you man, this is an article about growing weed. Stay safe and enjoy I guess lol.

  2. I water in the middle of the day for indoor grows and before I go to bed for outdoor. I’ve had some plants that had no real strict schedule with watering and they did just fine. I feel watering is one of those things where you just feel it out and if it’s too dry, then water the ladies.

  3. Garden essentials

    I reаⅼly like it when peopⅼee gеt together aand share opinions.
    Grеat website, continue the good work!

  4. Gerald Cummings

    Remember, the ways to grow a garden is relative to each individual…what works for some folks ,might not work for you, and visa-versa. You must experiment, and be prepared to learn from your mistakes…and you’ll make the odd mistake…just be patient, it’s a plant, let it grow.

  5. What is the effect on plant growth, if you just put the seeds into earth (outdoors) and let it grow automatically, the roots should do the job and the plant would be adapted to the little water. Are the buds smaller or what will happen ?

    1. Scarlet Palmer - Sensi Seeds

      Hi Henning,

      Strictly speaking, we cannot answer questions regarding growing in the comments. However, in this case I can tell you that there are so many variables not specified in your question that it is not possible to answer it practically either! Sorry about that. You might find this article about tips for outdoor growing interesting though.

      With best wishes,

      Scarlet

  6. Thanks for the concise information, to the point. Just some advice for everyone out there: If you’ve never grown a plant before, any plant, or if you really have no idea how to grow one, then you may want to hold off on growing cannabis. This comment section is chock full of very basic questions that someone should absolutely know before jumping into a cannabis grow. If you don’t know how or when to water a plant, you should probably practice with a houseplant or something similar first, otherwise you’ll have a bunch of problems and end up on the comment section of some blog where the authors aren’t even allowed to answer your questions. That’s what the Forum is for.

    1. Good thing your not the one running this website!! How you’ve laid back and lit one up and have a different attitude now? Have a hap hap happy day!!!

  7. Yeah I will share here the Tips which has been passed from my Indoor Landscaping Team Near me (Sijigreenhouse) on How to water cannabis properly (when using a well-draining mixture with liquid nutrients)…

    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).

    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).

  8. If you want a stable environment in the pot and good respiration for your roots DO NOT allow any runoff to appear from the bottom of your pots. Give the plants only a little water at a time. Do not suffocate them by drowning. Although water contains oxygen the roots can and will be restricted in their respiration. Don’t do that unless you know that your garden climate conditions and your substrate quality will permit all of that water to drain out of the bottom of your pot fairly quickly. One day is “quickly”. Three days in stale water – not “quickly” at all.

  9. I’m looking to start to grow a “trainwreck” or “Girl Scout cookies” in my shed outside it has been covered in tin foil, I have a list of equipment would this be fine to start growing?
    Exhaust fan
    Lighting
    Fans
    Pots
    Grow kit
    Temperature control
    Pest control
    Soil
    Seeds

    1. Scarlet Palmer - Sensi Seeds

      Hi Mitchell,

      Thank you for your comment ? Unfortunately, for legal reasons we cannot respond to grow questions on the blog, but we do have the Sensi Seeds Forum where you can ask a thriving community of gardening fans for advice, share your experiences, and see if your question has already been covered. You can also check out these articles, which have additional information about growing as a beginner: Build the best basic indoor grow setup, and Top five tips for growroom safety. It’s not clear from your comment, but I hope you don’t mean you have covered the outside of your shed with tinfoil?! You should definitely not do this, as all it will do is attract attention… 😉 I hope this helps.

      With best wishes

      Scarlet

    2. I honestly wouldn’t recommend using tin foil at all. With a shed, and this is my opinion.. u can look into yourself if u want to.. but I’d recommend painting the entire interior FLAT WHITE, u can get more light to shine off that than u can off of any type of tin foil. That would be a last resort for me. And if u wanna go the foil route, then Mylar sheets are ur best bet. With foil, for it to work, it can’t have any creases or anything in it, it has to be completely flush against the wall for it to even semi-work. But if u go the paint route make sure u get the FLAT WHITE PAINT. It might sound good but glossy white paint works even worse than regular tin foil. This is all coming from trial & error experience, so take it or leave it.

  10. Hi ! how often I should use nutrients when I watering my plants , for example I’m using Soil Bloom + Soil PK Boost , all the time when I’m watering , now I’m flowering period and I’m watering one time in 3 days or 2 , I need to use all the time nutrients ? or pure water ?

    Thanks

    1. Scarlet Palmer - Sensi Seeds

      Hi Grigore,

      Thank you for your comment ? Unfortunately, for legal reasons we cannot respond to grow questions on the blog, but we do have the Sensi Seeds Forum where you can ask a thriving community of gardening fans for advice, share your experiences, and see if your question has already been covered. I hope this helps.

      With best wishes

      Scarlet

  11. Very helpful, answered a pressing question, and the answer is no worries!

    Thank you

  12. I’m growing in the ground just moved to a new place and my soil stays wet should I still water or just add nutrients this is first time I’ve had this problem

    1. Scarlet Palmer - Sensi Seeds

      Hello Will,

      Thank you for your comment ? Unfortunately, for legal reasons we cannot respond to grow questions on the blog, but we do have the Sensi Seeds Forum where you can ask a thriving community of gardening fans for advice, share your experiences, and see if your question has already been covered. I hope this helps.

      With best wishes

      Scarlet

    1. Scarlet Palmer - Sensi Seeds

      Hello Nick,

      Thank you for your comment ? Unfortunately, for legal reasons we cannot respond to grow questions on the blog, but we do have the Sensi Seeds Forum where you can ask a thriving community of gardening fans for advice, share your experiences, and see if your question has already been covered. I hope this helps.

      With best wishes

      Scarlet

  13. notacriminal

    I’ve been told that, if growing in soil, pH adjustment of fertilizer and water isn’t needed, since the soil acts as a pH buffer. You still need to watch the runoff, and if it’s out of whack, you gotta adjust the soil itself, ex with dolomite lime. Always take a small amount of soil and do a soak test before planting anything.
    Also worth mentioning that most fertilizers will auto-regulate their pH. At least, the organic stuff I use does.
    I feel like there’s some confusion between growing hydroponically and in soil, since with hydro you do need to watch the pH of things going into the basin.

  14. Steven Campbell

    Hi can u tell me something do u ever give your plants just water now and again?

    1. Scarlet Palmer - Sensi Seeds

      Hi Steven,

      Thank you for your comment ? Unfortunately we cannot respond to grow questions on the blog, but we do have the Sensi Seeds Forum where you can ask a thriving community of gardening fans for advice, share your experiences, and see if your question has already been covered. I hope this helps.

      With best wishes

      Scarlet

  15. makes india clean

    Nice of the water treatment plant and Rain Water Harvesting is a process of saving the rain water in storages and subsequently using it for specific purposes. The rain water is collected from roofs and the other high places, from where the water is falling on the ground. This rain water is stored in deep pit or reservoir The collected water is used for the many purposes such as domestic use, irrigation, gardening, ground water recharging and drinking.

  16. CoviKlaFlaire

    I got one question, How often do i Add ferts to water? My girls need water every 5 days, and on AN schedule says how much ferts they need on a weekly basis..Should I add ferts every watering or?

    1. Scarlet Palmer - Sensi Seeds

      Hi CoviKlaFlaire,

      Thank you for your comment ? Unfortunately we cannot respond to grow questions on the blog, but we do have the Sensi Seeds Forum where you can ask a thriving community of gardening fans for advice, share your experiences, and see if your question has already been covered. I hope this helps.

      With best wishes

      Scarlet

  17. Does any one have the water requirements (or a rough idea) for plants that are propagating indoors? Also how much less water does a plant that is in vegetative growth use compared to a flowering plant? Any ideas or suggestions would be great!

    Thanks.

    1. Scarlet Palmer - Sensi Seeds

      Hello Nate,

      Thank you for your comment ? Unfortunately we cannot respond to grow questions on the blog, but we do have the Sensi Seeds Forum where you can ask a thriving community of gardening fans for advice, share your experiences, and see if your question has already been covered. I hope this helps.

      With best wishes

      Scarlet

  18. My plants seems dry on top but they are still super heavy i dont understand they are dry even 5cm deep but they weigh a ton like i juste watered them ??

  19. diskokobaja

    one newbiecquestion, i hawe 3 half succcesfull grow behind me, im still confused about feeding ,i use 5 gal pots and in the most hot days i doont need to water them sooner that every 5 day.. sometimes and more.. so shoild i gave th3m ferts with every watering or??

    1. Scarlet Palmer - Sensi Seeds

      Hello Diskokobaja,

      Thank you for your comment ? Unfortunately we cannot respond to grow questions on the blog, but we do have the Sensi Seeds Forum where you can ask a thriving community of gardening fans for advice, share your experiences, and see if your question has already been covered. I hope this helps.

      With best wishes

      Scarlet

  20. I have a few questions. 1 I’m growing outdoor and I bought hydroponic nutrients for my cannibus. Is it ok to mix the solutions and water the plants right after? 2. If the Ph for the soil is different than the ph in the solution how do you fix that? Thanks!

    1. Scarlet Palmer - Sensi Seeds

      Hello Nando, thank you for your comment.

      For legal reasons, Sensi Seeds cannot answer questions about growing on the blog. However, we do have the Sensi Seeds Forum, where you can find lots of information about many grow topics and also ask questions. I hope this helps 🙂

      With best wishes,

      Scarlet

      1. Scarlet Palmer - Sensi Seeds

        Hello e,

        No, I can reassure you it’s still 2016, and yet due to legislation in the Netherlands we still cannot answer grow questions on the blog because we must walk a very fine line between providing information for educational and entertainment value, and encouraging people to break the law (I don’t like it either but that’s just the way it is). Hope this clears up any confusion. 😉

        With best wishes,

        Scarlet

    2. 1. You can feed with a mix of hydro nutes and then water after, though I personally just mix the nutes with the amount of water I intend to use so it’s all done at once. 2. Don’t worry about the ph; good soil is awesome at regulating it without your help.

  21. Do you HAVE to feed cannabis plants nutrients? I don’t know what or how to feed my plants, is it better for me to just not feed them nutrients at all? (But still water them of course)

    1. It’s alot better yes, Alaska fish fertilizer is good and easy to find (Fred Meyer for me) use directions on bottle, probably a teaspoon or two per gallon, use the 5-1-1 until you see flowers then switch to the bloom blend, it has lower N. Feed, water, feed, water, Use a teaspoon of CalMag EVERY watering until you see flowers. I use General Hydroponics Grow and bloom blend + other stuff. Anything sea or fish based is candy to MJ.

    2. Mitchell Pettengill

      It is my understanding that you do not have to give them nutrients however if you want to get the most out of your plant nutrients are advised

    3. if you want to lose quantity sure dont use any plant nutes, but you are probraly gonna run into some sort of nute-problem where u need something (organic or something u can flush out of the soil at 2-3 week before harvest..

    4. Forbidden Fruit (@BannedintheUSSA)

      Not if you use a rich soil like Black Gold or Happy Frog. Fertilizers are optional as they grow older & have used up what’s in the soil, but for me nutrients–especially the chemical kind–just complicate things.

      There are tons of natural, cost-effective ways to enrich your soil to feed your plants if you choose to. Watering your plants occasionally with aquarium water or diluted human urine (1 cup urine to 8 cups water) are a couple examples. Banana peels can also be boiled to make a potassium-rich fertilizer. Just Google “natural cannabis fertilizers” & you’ll find tons of stuff.

      But again, these are all optional. You’ll get bigger buds if you use fertilizers the right way, but as a new grower there’s also more chances to mess up. Some mediums like hydro & coco coir might require fertilizers; I’m not familiar with those. But with soil it’s optional.

    5. Gerald Cummings

      If you purchase Fox Farm soil mixture, you won’t be needing any nutrients for awhile. There’s nutrients in the soil already.

    6. yes, mine are outdoors been growing for 15 yrs in the nevada desert.
      its all about great soil proper watering i do 6 plants, 3 with all the chems and mircle grow . 3 just grow, water and good soil the diffrence is slight they are 6 ft high and 6 ft wide and pretty to look at.harvest at halloween

  22. Help! I over watered my plant.

    Watered it about 1pm est and within 2 hours, it basically looks like the leaning tower of pisa. Brought it inside and stuck it next to my boiler about 2 hours ago (its now 8pms est). The plant is young as well. What do you recommend? All advice is appreciated.

    1. If its soaking you might be better to transplant into another pot with fresh soil and perlite, if the roots are starting to smell and decompose into a compost-like material, you will need to cut the bad off before repotting. Only cut what is definitely diseased or rotting. Do not feed same day as repotting and put under low intensity light.

    2. Gerald Cummings

      Don’t put it next to a heat source after drowning it with water bud…make sure your container has holes in it so water can drain out and just let it dry out by itself. You could get a new pot, new soil and transplant it if its fuktup.

    1. Realy? Email me if u could I got a few questions if u could awnser I'm a rookie

      Hey I’m a rookie and I was wondering if u could email me I have a few questions I need awnserd

    2. Mitchell Pettengill

      You say not to PH down if your growing in soil but my water coming out of the faucet is over 9.5 pH I am not in the ground I am in 7 gallon pots will the soil still stabilize my pH

      1. Make sure your pH tester works I bought 2,at homee depot to check and both both read diferent bought 2 more and took back. I was told from home depot to go to nursery and buy ocean breeze one soil perfect for pot 15 a bag already has bat guano just add 2shovels full of perlite to to nursery an tell them for pot plants very with big buds usi ng only 1/4. To 1/2 what it. Calls for get a didital tester or buy water pure I do at half life also and 2
        1/2 teaspoon of molasses mix sit by plants per gallon let zit water even with outdoor temp use only top 3/4 of gallon salt buildup at bodem throw away let dry out good. Happy bid bid to you. Steamer

    3. Really?? I have grown before in soil without bothering with ph ect just tap water or rain had no problems whatsoever grew some magical stuff

  23. I can give you a really good organic soil mixture, that you can use outside, and produce some nice crops. Start with a whellbarrol. Get you some Horse, about 50 pounds wet, and compost it for about 6 months in this mixture. Go to walmart, and pick up one bag of Jungle Grow organic soil, 1 bag 40lb Top soil, 1 bag 50lb Black cow, and a 40lb bag of powder lime. Use about 20lbs of the line. Mix all up in to wheelbarrol, this time of the month would be perfect. By April you will be ready to dig your holes and put in your soil mixture. Dig out about enough room for about 7 1/2 gal and fill up hole. Start your seedlings in March, and they will be ready to plant on April first. This will take you all the way through veg stage, and you want need any fertz until they start to flower. Get you some Maxi Grow 5-15-14 Bloom, and put on once a week. 5grams with one gal of water. In 8 weeks you will have some really nice plants. good luck and happy growing.

      1. I think this way sometimes but realize if cured to long it gets mould..i think from the day you cut the plant down dry it and cure it and in jar s ready to be sold total for really fresh taste like 10-14 day max…no long time cure potentcy goes south

      2. Bad idea. It wont add anything to your potency (if thats what you are thinking) and will most likely be harmful. Bongs and hookas are breeding grounds for mold.

      3. Gerald Cummings

        No…don’t put that shit in your plant. The plant likes water not resin from smoking.

      4. Nicotine is harmful to plants, a poison just like it is to pests which is why the plant produces it. Your an idiot if you add hookah water to your plant

  24. Denise Cannam

    Thank you for all the great information here. I grow only outdoor cannibus. It would be awesome to have more information here for outdoor growing, like you guys have for indoor. I have been struggling for a few years now with my grows. My husband is very old school. He will say ” it is just a weed, it only needs water.”, well yes and no, if you want quality and quantity you must do more. Now a friend has been telling me every thing is wrong, feed only at night, etc. So, I am starting all over, and in need of help and correct information.

    1. If you’re an outdoor grower; a helpful hint to maximize potency and best results in your buds is to cure it once it has been harvested. Curing means: Keeping your buds in a mason jar for at least 2- 4 weeks, the longer the better. Almost like a fine wine, age makes perfection.

      1. Scarlet Palmer - Sensi Seeds

        Hi Snuffy and Denise,

        Excellent advice, curing makes a world of difference. I’m going to add that you should open the mason jars a couple of times a week for 10-15 minutes, to allow fresh air to circulate. Happy curing!

        With best wishes,

        Scarlet

      2. I think this way sometimes but realize if cured to long it gets mould..i think from the day you cut the plant down dry it and cure it and in jar s ready to be sold total for really fresh taste like 10-14 day max…no long time cure potentcy goes south

      3. Do you put the buds straight into the mason jar after they’ve been cut and trimmed from the plant?…like no airdry time?

        Thanks.

  25. william riesman

    Thanks for the tips. Not a rookie but just was interested in another viewpoint. I am growing something from Amsterdam and it is doing well. William

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    The Sensi Seeds Editorial team has been built throughout our more than 30 years of existence. Our writers and editors include botanists, medical and legal experts as well as renown activists the world over including Lester Grinspoon, Micha Knodt, Robert Connell Clarke, Maurice Veldman, Sebastian Maríncolo, James Burton and Seshata.
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