How Often Should I Water My Cannabis Plants?

Knowing the right time to feed your plants can depend on many variables, so find out more below about what to consider in order to maintain the perfect watering ratio.
19 February 2021
20 min read
How Often Should I Water My Cannabis Plants?

Conținut:

If you are new to growing Cannabis indoors or outdoors, having a thorough understanding of how frequently you should be watering or how often your plants require it can be quite difficult. There are many factors that play a huge role such as the pot size, strain, conditions, and substrate. In general, you should water when the medium is around 60-70% dry.

Below we'll explain what you should know when it comes to watering your Cannabis plants.

1. Factors That Influence Cannabis Watering

First of all, every grower needs to understand that a question like “how often should I water?” is basically pointless because your watering schedule will depend on your own specific growing environment.

There is no set way to water Cannabis plants or the best time to feed cannabis plants, or any type of house plant for that matter, however, each grower has their own set way, based on what is most practical for them. 

 

How often should I water my plants: influences

There's no watering schedule that works for all cannabis plants because each cultivar is different.
 

There are multiple elements that can dictate how much water or how often you need to water your cannabis such as genetics, the phase your plant is in, growing setup and if you’re feeding with every watering or not, but the main ones are pot size, medium, and the environmental conditions.

Medium 

As you may know, the substrate is where the roots will be growing, and depending on your preferred mix, it can hold more or less water which can affect the amount of water you need to water with and how long it takes for the water to evaporate.

For example, if your substrate contains more perlite, it will allow more oxygenation which can increase the evaporation rate, or if it contains a lot of coco fiber it can take longer for the water to evaporate due to coco being able to retain water for longer.

Pot size

Another factor that can affect how often you water your cannabis plants is the pot size because if there’s more substrate you will have to water with more water and it will take longer for the water to evaporate, obviously, this depends on the stage your plant is in.

If your plant is still a seedling you don’t want to water with a lot of water even if it’s in a 60L pot, but as it grows, you will have to water more and it will take longer for the water to evaporate  (when compared to a 10L pot) depending on the conditions.

Environmental conditions

But the main factor that influences how often to water is the growing conditions. This happens because, if the humidity levels are too high it will take longer for the water to evaporate whereas if the humidity is too low, water will evaporate faster.

 

How often should I water my plants: environmental conditions

You may need to water more or less often depending on the environmental conditions.
 

Also, if the humidity is too high it will encourage the transpiration process, making plants absorb more water and evaporating it faster while a lower temperature slows down transpiration and will take longer for the water to evaporate.

2. The Best Way To Water Cannabis Plants

As said above, there’s no better way to water plants, this will depend on your setup. There are several ways to water plants, either by hand-watering, having a drip irrigation system, and bottom feeding among others.

Soil and coco

Soil and coco (with any other things mixed in such as perlite and etc.) are the most common mediums and allows you to water any way you prefer.

Hand watering

 This is the most basic way to water a weed plant. Normally you will add enough water until you see runoff. By watering weed in this instance, the growing medium will always stay well saturated, yet will never be encouraged to dry out and increase air capacity.

Bottom Feeding 

A very simple and foolproof way to water your cannabis plants by allowing the roots to suck the water up. This only happens correctly when the growing medium is dry enough, to cause a wicking action that will draw the water upwards to the roots.

 

How often should I water my plants: the best way to water

There are many methods to water your cannabis plant so you should go for whatever suits you better.
 

Many growers swear feeding in this manner is the most advantageous, then again many will debate that the buildup of salts is far greater.

Drip irrigation system

A drip irrigation system is not very common amongst soil growers but it can be a great choice for coco or hydro growers. This method consists of a small hose on top of the pot that waters your cannabis plants by releasing drops of water non-stop.

So to help you have an idea of how much to water and how often, here’s a small guide to help you water your cannabis properly.

 

Cannabis watering schedule for beginners

 SeedlingVegetativeFloweringFlushingHow often?
Coco or Soil≈100-200ml≈300-600ml≈700-1500mlUsual amount of water + 10-20%Every 2-4 days

 

Just have in mind that this guideline was designed for plants grown in 10-12L pots and under optimal conditions, which are:

 

  • Seedling stage - 65-70% humidity and 20-25°C
  • Vegetative stage - 70-40% humidity and 20-26°C
  • Early Flowering - 40-50% humidity (lowering approx. 5% each week) and 22-28°C
  • Late Flowering - 30-40% humidity and 18-24°C

 

How often should I water my plants: metabolism

Your plant's metabolism is affected by the conditions and will determine how much water your plant absorbs.
 

Just have in mind that even if your growing the same strain, it all comes down to your plant's metabolism wish is affected by the conditions, so for example, if you’re growing our Wedding Cheesecake Auto under 30°C in 45% humidity, your plant will need much more water than the same strain under 25°C in 60% humidity.

Hydroponics

Now, when growing hydroponically you need to have a drip irrigation system or any other system that waters your plants automatically. Watering using timed irrigation not only saves physical labor but also ensures the cannabis plants are fed the exact same amount, on a consistent basis. Organic growing mediums fed with drip stakes will grow much faster than when hand watering, and is replicated on enormous scales in the agricultural sector.

 

Cannabis watering guide for aero and hydroponic setups

 SeedlingVegetativeFloweringFlushingHow often?
Hydro (Perlite, clay pellets, or rockwool)100-400ppm500-1200ppm100-1600ppmAs close to 0ppm as possible15min ON, 15min OFF (24/7)
Aeroponics100-400ppm500-1200ppm100-1600ppmAs close to 0ppm as possible5s on 4-5min off (24/7)

 

So, to help you avoid overfeeding and give you an idea of how much you should feed your cannabis, here’s a table for hydro and aeroponics. Have in mind that the amount needed for soil or coco will differ depending on the brand you’re using so you should follow what they recommend.

When growing in hydro or aeroponics, it’s better to feed your cannabis by measuring the parts per million (which is basically the amount of nutrients in the water in a 1/1000000 concentration) in your nutrient solution.

 

How often should I water my plants: hydroponics

When growing in hydroponics or aeroponics you should always measure the ppm!
 

Measuring ppm instead of measuring by ml/L it's better because you get a more exact amount of nutrients, water contains a small amount of micronutrients (aka trace minerals) and due to your cannabis being directly exposed to the water, they will end up absorbing it.

So when growing in either of these methods, we highly recommend measuring the pH and measuring the ppm of not only your nutrient solution, but also of the water source; Remember that water purity is very important when growing in hydro or aeroponics.

3. Plain Water or Nutrient Solution? 

Hydrating a plant is one thing, however, feeding a nutrient solution is different and there are a few things to consider. The root hairs of a Cannabis plant only need to come into contact with a fine film of water to be able to tap in and extract what they need.

Feeding Plain Water Only

This is basically as organic and simple as one can be, as Mother Nature does all the rest. As all of the necessary primary and trace elements can be found in abundance inside an organic living soil, all that is required is to keep the moisture levels adequate for the living microorganisms.

Compost also depends on specific temperatures and moisture levels in order for organic matter to break down over time.

Nutrient Solution

Most growers who follow a nutrient feeding chart will feed a mix of different nutrients until the final few weeks. During the last part of the flowering cycle is the flushing period where plain water is fed to the plants for two reasons.

Break Down Undissolved Salts

The build-up of nutrient salts that can develop over a 10 week period or more can be quite excessive. Especially if using chemical-based nutrients that are designed for hydroponic systems.

 

How often should I water my plants: nutrient solution

You should flush for at least 7 days, during this period it's normal if the leaves start to yellow.
 

Water is the source of life and is also a solvent in its own way, meaning the final 14 days will help wash away (aka flushing) the remaining salts increasing the flavor and quality of the ash.

Using Up The Reserve Nutrients

Even though it may seem a drastic change to switch from a maximum nutrient solution, it is necessary to starve the plant forcing it to use up all of the reserved nutrients. This is when Cannabis plants will begin to exhibit rapid deficiencies and is a sign the nutrients are being used up.

4. Oversaturating The Cannabis Grow Medium

There is nothing worse than having the best intention, but unfortunately, too much water or nutrients does not result in more growth, so overwatering or overfeeding your cannabis will have a toll on your plants.

Overwatering

In the event your growing medium is inadequate regarding drainage and water-retaining capacity, then the water evaporation can be very slow causing many issues to occur.

Transpiration that occurs through the leaves will need to compensate for the excessive amount of water around the roots. As plants find a way of transporting water through foliage or the root zone, by oversaturating you are jeopardizing the integrity of the plant’s growth, causing stunted growth.

Also, wilting of the fan leaves is a clear indication you have over-saturated your root zone, and the plants are not happy. 

 

How often should I water my plants: overwatering

Overwatering should be avoided so you don't stunt plant growth.
 

This can also happen when underwatering, which is when your plant is lacking water.

Even though underwatering shows the same trait, do not feed more water and allow your growing medium to air out until the pot is light to pick up.

A cold and wet root zone will cause anaerobic bacteria to infect your garden and kill your cannabis. It is extremely important to keep your root zone oxygen-rich and one reason why felt pots are so popular. 

And when this happens, cannabis plants will fail to uptake certain much-needed nutrients if the water levels are too great. 

Overfeeding

Just like when watering in excess, feeding with a too strong nutrient solution will cause the minerals to build up and the results will be a lockout in nutrients and a line of deficiencies to begin occurring one after another.  

This happens because cannabis can’t use the excess minerals and they end up burning the tips of the leaves and can end up burning the whole leaf if not dealt with fast.

 

How often should I water my plants: overfeeding

Overfeeding will affect plant growth so make sure you keep an eye out for deficiencies.
 

As the nutrient burn continues, the tips of the leaves will start to get brown, crispy, and sometimes twisted; This is very common when using bottled nutrients, that’s why it’s a good idea to look into organic feeding if you have access to them.

This is where the importance of pH levels in water comes in; Maintaining pH levels in between the acceptable range (for each specific medium) is one way to avoid this kind of problem because the pH level can block the roots from absorbing the nutrients your plant needs. 

So even if you’re feeding your plant properly, higher or lower pH may prevent them from absorbing them and result in similar symptoms as overfeeding but will actually be caused due to the lack of nutrients, known as underfeeding.

Flushing

When your plants are suffering from pH problems or an excess of nutrients, flushing is the best way to solve your issues, and to do it correctly, you will have to water your plants with plain pH’d water.

 

How often should I water my plants: flushing

Flushing allows you to correct the ph and remove the excess nutrients in the medium and roots.
 

This will correct the pH levels and wash off the excess nutrients in the medium and the roots, allowing you to start feeding your plants from scratch or correcting the pH level, allowing your cannabis plants to absorb the nutrients they need once again.

Top Tips for Marijuana Watering

So, if you’re a beginner grower here are a couple of tips to avoid having some of the problems cited in this article:

  • Know when to water by weighing the pot

A good way to calculate the watering ratio is to feel the weight of your growing medium when it is at the lightest with no water. This is the point your plants need to be each time before watering. By doing this you will always know when to water without running the risk of overwatering. 

 

How often should I water my plants: top tips

Top watering tips for beginner growers!
 

  • Use your finger to check if the medium needs more water

If you are hand watering and are not sure if the medium is wet enough, simply insert your entire finger down the side of the pot. Judge how moist or dry your finger feels and this should give you a clear indication of when next to feed.

  • Water plants with room temperature water

It is better to water plants with room temperature water (around 20-23°C), as cold water can cause shock and encourage a cold root zone.

  • Water your plants when the lights are ON or up to 30min before 

Avoid watering close to lights out, as the plants will not get a chance to use it until lights are on. Humidity levels in the garden can increase and oxygen levels and temperatures around the roots will drop.

Best Recommended Heavy Feeders

For all the growers who like to give their ladies the best nutrients on the market, we have picked our 3 biggest feeders to keep you company in the grow room.

Gorilla Glue Auto Glue Auto
Gorilla Glue Auto (Glue Auto)
Gene
Sativa/Indica
Genetică
Gorilla Glue autoflowering
Înflorire
9-10 weeks
Recoltă
XL
Înălțime
60-100cm
THC
24%
CBD
Low
Autoînfloritoare
Yes
1 fem
13,00 €
2 fem
24,00 €
3 fem
36,00 €
5 fem
55,00 €
10 fem
99,00 €
25 fem
215,00 €
50 fem
365,00 €
100 fem
590,00 €
500 fem
1 950,00 €
1000 fem
3 400,00 €
Pack
3 fem
Adaugă în coș
36,00 €
 

A rock-solid performer who can take heavy and frequent feeding, and she will grow big fat buds in return.

This is a resilient strain that needs that extra nutrients to be able to develop the big fat nugs so make sure you feed it properly, always keeping an eye out for signs of deficiencies.

Orange Sherbet Auto
Orange Sherbet Auto
Gene
Mostly Sativa
Genetică
Orange Sherbet Auto
Înflorire
9-10 weeks
Recoltă
500-650gr/m2
Înălțime
110-150cm
THC
up to 24%
CBD
Very low
Autoînfloritoare
Yes
1 fem
13,00 €
2 fem
24,00 €
3 fem
36,00 €
5 fem
55,00 €
10 fem
99,00 €
25 fem
215,00 €
50 fem
365,00 €
100 fem
590,00 €
500 fem
1 950,00 €
1000 fem
3 400,00 €
Pack
3 fem
Adaugă în coș
36,00 €
 

When it comes to the biggest autoflowering cultivars around, this lady is certainly up there with extra-large yields and a big thirst.

This plant grows quite big for an autoflower despite its Sativa heritage so it will need that boost when it comes to nutrients to be able to develop big and strong and be able to withstand the weight of the huge amount of buds during flowering.

Gorilla Cookies Auto
Gorilla Cookies Auto
Gene
Sativa / Indica
Genetică
Gorilla Cookies Auto
Înflorire
10 weeks
Recoltă
500-600gr/m2
Înălțime
90-100cm
THC
Up to 27%
CBD
Very Low
Autoînfloritoare
Yes
1 fem
13,00 €
2 fem
24,00 €
3 fem
36,00 €
5 fem
55,00 €
10 fem
99,00 €
25 fem
215,00 €
50 fem
365,00 €
100 fem
590,00 €
500 fem
1 950,00 €
1000 fem
3 400,00 €
Pack
3 fem
Adaugă în coș
36,00 €
 

Another big feeder who loves a high nutrient ratio, thanks to her Indica-dominant lineage. This strain grows quite stocky and produces huge yields, that’s why you should feed her properly, and in return, it will produce lots and lots of resinous buds and in a big quantity.

Just remember that despite being heavy feeders, you should always pay attention to any signs of deficiency and increase the nutrient dose gradually to avoid stunting growth!

7. In Conclusion

Having a reference when your growing medium is the most lightweight, is a great start point for a beginner grower to work with. Finding the balance of how much your plants are drinking as well as transpiring is a learning curve that can take hands-on experience and require multiple grows under your belt.

Once you find the perfect mix, your Cannabis plants will respond in kind, and remember less is more sometimes. And remember that if you were wondering how to water outdoor cannabis, the process is basically the same but you should be extra careful on rainy days.

For those of you who have the watering game on point, feel free to leave your tips in the comment below to help out fellow growers!

 

This post was most recently updated on February 19, 2020.

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