by Seshata on 24/12/2014 | Cultivation

How to water a cannabis plant

Growing 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 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.

How to water a cannabis plant

Moderation is key

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.

botrytis

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!

morning_sunrays

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.

large_cannabis_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.

PH_Meter

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.

Comment Section

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Gus

Thank you very much for this information you have provided us!

11/05/2015

It was of great help

It helped greatly

03/06/2017

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

02/07/2015

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.

06/09/2015

King herbal

Mornings is the best time 6am

15/03/2016

Snuffy

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.

15/01/2017

Hotshot

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.

29/09/2015

earl smith

what do u think of useing HOOKAH water to use to water plant???????

22/01/2017

Hotshot

Thank you for this Article.

01/10/2015

drfour20

Never adjust ph for plants in soil.the soil does this .

17/03/2016

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

10/04/2016

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

28/05/2016

Kittykat

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

10/08/2016

No not true at all

Soil does not balance ph

04/10/2017

John

Very useful information but at what age do I need to start feeding them

06/04/2016

Cc

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.

10/05/2016

sjw3206

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.

22/05/2016

Ross

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)

12/05/2016

Jason

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.

24/05/2016

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

28/05/2016

Nando

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!

24/05/2016

Scarlet Palmer

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

24/05/2016

Red

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.

09/09/2016

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??

01/06/2016

Scarlet Palmer

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

02/06/2016

Highasfok

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 ??

15/07/2016

Nathan Foster

Finaly! Something actualy understandable! lol

19/07/2016

Nate Jones

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.

10/08/2016

Scarlet Palmer

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

16/08/2016

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?

29/11/2016

Scarlet Palmer

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

30/11/2016

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.

13/12/2016

Steven Campbell

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

21/01/2017

Scarlet Palmer

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

23/01/2017

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.

21/01/2017

Darnell

What great info.Thanks for the grow info we can use

22/01/2017

Nick

should super thrive be used and when

16/02/2017

Scarlet Palmer

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

17/02/2017

sherry

Didn't need all that info.do you water weed plants every day once a weed.how often?

23/04/2017

Will

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

27/04/2017

Scarlet Palmer

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

08/05/2017

Deserttrek

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

Thank you

24/06/2017

Grigore

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

04/07/2017

Scarlet Palmer

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

07/07/2017

Mitchell

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

27/07/2017

Scarlet Palmer

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

14/08/2017

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