How much water does a weed plant need and how often should I water my weed plant? Curious? Find all the answers here! Check it out! Learn everything you need to know about watering your cannabis plants. No more guessing or worrying! Wondering how often to water cannabis or the best time to water weed plants? Check out our How to Water Cannabis Guide to get all the answers.
How Often Should I Water My Weed Plant?
How much water do weed plants need and how often should I water my weed plant? These are questions we receive quite often from novice growers. Time to write a blog about it!
Whether you grow weed plants in soil or some other medium such as coconut coir, watering is an important consideration that is vital to the success of your crop. Cannabis plants cannot survive without water, but when the compost is too wet, oxygen cannot get to the roots, which causes them to choke.
How much and how often do I have to water my cannabis plant?
How often and how much water you have to give to your cannabis plant is usually hard to describe. It isn’t an exact science. Autoflower strains generally need less water and can handle a mistake in watering more easily compared to feminized strains.
Yet, whatever the strain you grow, if you do not give enough water to a weed plant, it will start to sag and the growth or flowering will slowly stop. It is, therefore, important that your weed plant receives sufficient water and regularly. If you always wait until the leaves hang limp before giving water, the plan will experience stress, resulting in delays in the development of the weed plant. How often and how much water you have to give to your cannabis plant depends on several factors:
The size of the pot
The pot size ultimately determines how often you have to water your weed plant. A large pot with soil dries out much less quickly than a smaller pot with soil, so you will have to water more often to prevent dehydration. It is important that you regularly feel the earth to see if it is damp enough. Using a small pot means that the earth in the pot will heat up much faster, which will cause your earth to dry out extremely quickly. It can dry out so quickly that your pot will be completely dry after 12 hours.
Temperature in the grow room
The higher the temperature in your grow room, the faster moisture will evaporate and consequently the moisture in the soil. Since a weed plant likes higher temperatures, there is a good chance that it will be warm in the grow room. Most of the heat from the grow room comes from an HPS lamp. The higher the wattage of an HPS lamp, the more heat it emits.
When to water your weed plant?
When do you know if you need to water a cannabis plant? There is a good way to do this and that is with your hands. Earth must contain moisture, completely dry earth that is almost loose is not good. It is also not good if your pot of soil is a mud bath. Make sure you have a good middle ground, feel the earth and, if necessary, put your finger into the earth. This way you can easily estimate how dry the soil is and whether it is time to water your weed plant.
When the top layer of soil has become dry, the soil is no longer able to absorb water easily. This is easy to spot as the water runs out of the bottom of the pot almost as soon as you pour it in. When your pots are each on a separate dish, it doesn’t make a difference as the soil will absorb the water from the bottom.
However, when your plants are placed in a drip tray, it causes a problem because the water invariably runs to the lowest point and the plants that are there, absorb all the water from the other plants. This means that some plants receive hardly any water and others get too much. Growers often do not notice this straightway, which can lead to serious issues with the plants.
One way of preventing this is to either provide a separate dish for each plant, water in gradual stages or use a drop of liquid detergent. A flux reduces the water’s surface tension so that the earth is able to absorb it more effectively. You can also add a drop of detergent to a bucket of water but only use a tiny amount and not too often as the detergent can harm your delicate weed plants.
It is important to note that there is no general guideline to specify. A cannabis plant has different water needs at different stages and in different circumstances. However, there are some signs that the plant uses to inform you of its needs. Here are three techniques that can be used to ensure your cannabis plants are given just the right amount of water for their needs.
Method 1: Use your finger
If you want to know how much water is left in the tub, simply put your finger in it. This technique has been used for years and couldn’t be simpler. If soil sticks to your finger, it means that there is moisture in your pot. Water and earth make mud, and that sticks! So it’s fine if the top of the earth is dry, but your fingertips still contain bits of moist soil. That means that there is still some water under the dried-out layer. You can also use a skewer instead of your finger, which discolours due to water in the soil. This means that there is less chance of damaging roots.
Growing tip! Give lukewarm water. Let the water from your tap stand for a few hours so that all superfluous substances, such as chlorine, evaporate.
Method 2. Lift the pot regularly
This is one of the best methods but one that has to be done regularly over time. It’s simple: every time you water, you lift the pot. Lift it before and after watering. You will then automatically notice a difference in weight. Extra water makes a heavier pot. After a few weeks of practice, you will increasingly feel the difference. This allows you to perfectly estimate how much water your weed plant needs this time. Experienced growers only have to lift a pot to know how much water they have to give.
Method 3. View the appearance of the leaves
How much water do weed plants need? Your plant is actually able to show you. Do you see the leaves facing the sun? Are the leaves tilting upwards? These are good signs, your plant is happy with its growing conditions. Do you see leaves hanging down and looking droopy? Then there is a strong chance that you have given either too much or too little water. If you have not given enough water, the leaves will be very thin and fragile. If you have given too much water, the leaves are thick. After all, there is a lot of water in the leaf.
Method 4: Use a moisture meter/tensiometer
Insert a moisture meter into the soil and measure the amount of moisture there. This is a rather lazy method and is not always very reliable. Our experience shows that working with a similar instrument only causes long-term difficulties. Anyone can learn how to grow cannabis, including how to ‘manually’ determine how much your plant drinks. You need to know what to do if the meter’s battery runs out. How will you know how much water your weed plants need?
Growing tip! Is there dry and contracted soil in the pot? Does the water run underneath your pot along the edges? First, give half a litre of water so that the earth can expand. Wait for half an hour and then give some more water.
Growing tip! Do you grow with certified organic food and do you add useful fungi to your soil? Then your soil may well stay a little wetter compared to a mineral diet. The fungi and bacteria need moisture to multiply and stay alive. The fungi in the mycorrhiza also retain moisture and need moisture. Of course, you do not want your carefully constructed ‘living soil’ to be destroyed by a drought period. That would be a shame.
Create nutrient water
When preparing nutrient water, you must follow the correct order and give the water the chance to warm up to the right temperature. When the water is significantly colder than the ambient temperature, the cannabis plant suffers a temperature shock. Similarly, water that is too hot can lead to the roots struggling to get enough oxygen. The temperature of the water also affects the pH value.
The best plan is to allow the water enough time to heat up in your grow room until it gets to the right temperature. You could leave it overnight.
How to give the water?
You could use a watering can if you only have a few plants. Watering cans generally work well, but it’s difficult to water a large number of weed plants with a single watering can because you have to keep filling it up. Use a feed that is formulated for tomato plants.
A hosepipe connected to a large container is a good solution as you can add nutrients and ensure it is the correct temperature.
Keep the plants on trays or saucers so that excess water can be removed and the plants are not left in standing water. Trays are more convenient as you can deal with more plants at the same time.
Ensure that the pots or containers have plenty of drainage holes to prevent excess water from remaining and the roots from rotting.
You will need to water your plants more often at the start of the grow and less as they mature. Always check the soil every two or three days at a minimum.
Follow these tips for healthy cannabis plants and a delicious crop of weed!
How Often Do I Water Indoor Marijuana Plants?
If you’re growing marijuana in soil or another growing medium like coco coir, you will have to hand-water your plants. Watering is an important part of growing cannabis indoors, and knowing how to water your plants will save you a lot of frustration!
How often do you give your cannabis 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.
- Soil – Water plants when the soil feels dry up to your first knuckle (or if the pot feels light).
- Coco Coir – Aim to water plants every 1-2 days. If coco is staying wet for 3+ days, try giving less water at a time until plants get bigger and start drinking more. Don’t wait for your coco coir to dry out, but don’t water if the top inch feels “wet”. If the container feels light, it’s definitely time to water!
How to water cannabis properly (when using a well-draining potting mixture with liquid nutrients)…
In soil, wait until the topsoil feels 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).
In coco coir, you want to water every 1-2 days if possible and adjust the amount of water you give accordingly. The top inch doesn’t need to completely dry out between waterings.
If you’re regularly adding nutrients in the water, give enough water each time that you get 10-20% extra runoff water drain out the bottom of your pot. This prevents a buildup in the potting mixture because otherwise, you are continuously adding more nutrients to the system.
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) or need to give less water at a time. If your plants are very small compared to the container they’re in, give water more sparingly until plants get bigger.
Growing in Super Soil?
- If you’re growing in super soil or another heavily amended potting mix, you may not need to add extra nutrients to the water because your plants can get all their nutrients directly from the soil.
- Any time you’re not adding extra nutrients in the water, you want to avoid getting runoff water because it will carry away some of the nutrients in the soil.
- Watering until you get runoff is important when using liquid nutrients because it helps prevent nutrient build up, but with super soil try to give just enough water that you wet the entire medium but don’t get extra water coming out the bottom.
Some growers swear by 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.
I usually water my cannabis with a 1-gallon water jug for small grows, or 5-gallon jugs for larger ones. Runoff water is collected in the trays and after a few minutes I suck it all up with a small wet vac .
How to Provide the Water
When I first started growing, I gave my plants water using a watering can. A watering can works great, but it’s hard to water a bunch of plants with one watering can because you have to keep filling it up.
An old-fashioned watering can will get the job done, but they typically don’t hold a lot of water at a time, which is inconvenient if you’re growing a lot of plants
I personally like using a Battery Operated Liquid Transfer Pump to water the plants. You can pump water from a bigger container to your plants. This is a 3-gallon water container from Wal-Mart, and the pump just reaches the bottom.
My grow tent is 2 feet deep and this reaches the plants in the back. However, I don’t think the tube is long enough to reach the back if your space is deeper than that.
Some growers set up elaborate drip feeds to pump water if they have a lot of plants they can’t easily reach, both homemade or pre-made.
Let us know if there’s something we missed. Growers get creative!
How to Collect Runoff Water
It’s important to keep plants on saucers or trays so you can remove the runoff water. You can collect the saucers one by one and dump them out, but that also gets inconvenient with many plants.
It’s inconvenient to empty saucers one by one if you have a bunch of plants, but you don’t want to leave plants sitting in runoff water
If you put your plant on plastic trays, and then put the trays on a slight incline by putting something small underneath in the back, it will catch all the runoff water and cause it to drain to the front. The item in the back only needs to be about half an inch thick, for example a piece of plywood. However, if you can find something more water-resistant, like plastic, that’s even better.
These 1’x2′ plastic plant trays work well if they fit your space. You can fit four of them in a 2’x4′ grow tent (this is the grow tent I use) with up to two plants each as long as your plant containers are 11″ wide or smaller at the base.
Put trays on a slight incline by placing something underneath the tray in the back. This causes all the water to come to the front for easier collection. Each of these trays has a small plastic board (which we found around the house from something else) under the back. Anything that’s about half an inch high will do the trick. These particular trays accommodate plant containers up to 11″ wide at the base.
Not sure how to remove runoff water after watering your marijuana? Wet vacuums can be a great choice, especially if you already have one in the house. I didn’t have one, so I got Bucket Head attachment which can turn any standard 5-gallon bucket into a wet vac. You can buy one online but it’s $10-15 cheaper if you get it in person at a Home Depot. Another similar option is the Power Lid, though it’s also a bit pricey.
A downside to the Bucket Head is it’s a little loud, just like most wet vacs. Luckily you only need to use it for a few minutes after watering your plants!
Removing runoff water is a great start to make sure you are watering your cannabis plants perfectly, but it’s also important to…
Make Sure Pots Have Good 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, or some other way for extra water to escape), it’s also important to make sure your growing medium drains freely. If it takes several minutes for the 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
- Never use dirt you find outside. Chances are it does not have the correct properties for vigorous cannabis growth.
- Mix in extra perlite to loosen the soil and allow water to drain through more easily.
- Bark or wood chips are not the best choice for growing cannabis plants, even though they’re sometimes recommended to improve drainage in soil for some types of plants. On that note, avoid using soil that contains bark or wood chips. What makes soil good or bad for growing cannabis?
- Use Smart pots – these fabric pots help get oxygen to your roots (which gives you faster growth) and this type of pot makes it harder to overwater your plants. A cannabis plant growing in a tan fabric smart pot is pictured to the right.
This is an example of great soil for growing for cannabis – rich, composted, and well-draining
Composted super soil lets you grow organic marijuana without any extra fertilizers or nutrients
Watering Too Often? Barely at All?
In the beginning of your grow, you will likely be watering your marijuana plants every couple of days. Watering every 2-3 days is optimal for a young plant. If it’s taking too long for your plant to dry out, you may need to give less water at a time until the plant is growing faster.
If you feel like you are watering your plants too often, you may need to give more water at a time. You can also move plants into a bigger pot (which holds water for longer).
If plants take longer than 3-4 days to dry, make sure your potting mixture has good drainage and consider giving less water at a time
If plants are drying out in 1 day or less, try giving more water at a time or transplanting to a bigger pot
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 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.
That being said, you can plant your seeds right into their final container. Just be careful not to overwater your seedlings at first if they’re in a big container as they’re not drinking much water in the beginning.
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, as soon as the leaves reach the edges of the solo cup.
10-20% Extra Runoff Every Time You Water (if you’re providing nutrients in the water)
Every time you water your plants, make sure that you provide enough water to get about 10-20% extra run-off out the bottom of the container, especially if you’re feeding additional nutrients in the water.
Sometimes soil and soilless growing mediums like coco coir start to collect natural salts from fertilizers that never get washed out.
These built-up salts can eventually cause nutrient problems, pH problems, and nutrient lock-out if they’re not removed on a regular basis.
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.
Different Nutrients for Different Stages of Life
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.
If using nutrients on a regular basis by adding them to your water, it’s generally a good idea to give your cannabis plants nutrients every watering. This ensures the amount of nutrients in the plant root zone is kept relatively stable. If you notice the tips of leaves getting burnt from nutrient burn, it may mean you need to lower your overall strength of nutrients. Most nutrient recommendations on the side of the bottle are too strong for cannabis plants, and should be cut in half unless plants appear pale or lime green (which means they want higher levels of nutrients overall).
If Growing in Composted or Amended Soil, Give Just Enough Water That the Soil is Wet All the Way Through
When growing in composted and amended soil, the soil itself is made to slowly provide nutrients to your plant throughout its life. However, if you’re regularly watering until you get a significant amount of runoff, you’ll also be washing away some of your nutrients.
This is good when the plant is getting the nutrients directly in the water, to avoid unwanted buildup in the soil, but try to avoid a lot of extra runoff if you want your nutrients in the container to last until harvest.
Therefore, when growing in amended soil you should only water until you get just a drop or two of water runoff out the bottom. You want to ensure you gave enough water to reach the bottom of the pot without letting a significant amount of water run out the bottom.
Proper watering practices will greatly help reduce the amount of salt buildup and prevent nutrition problems from occurring.
If your cannabis plants shows signs of drooping, often the plant is getting too much or too little water, but not always. Drooping can be caused by….
- Too much water at a time, or giving water too often
- Not enough water at a time, or giving water too infrequently
- Drooping can also occur in hot conditions, or when it’s very humid or dry because the plant isn’t able to move water properly through the plant.
- Plants sometimes get droopy if they are given a lot of water after being allowed to dry out for too long, due to the stress of the water pressure quickly changing at the roots.
- Drooping is almost always associated with something going on at the roots, but plants also tend to put their leaves down a bit right before the lights go off, as if they’re preparing to “sleep” for the night. That can sometimes be mistaken as drooping when its actually part of the plant’s natural rhythm.
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 unless you plant is very small for the container). You should be getting 10-20% extra runoff water every time if you’re adding nutrients in the water. In soil, wait to water again until the top inch of the growing medium feels dry, up to your first knuckle or so. In coco coir, aim to water the plants every 1-3 days if possible, and don’t let the top completely dry out between waterings.
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
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
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
When is the best time to water weed plants?
Cannabis plants use a lot of water, and regardless of what sort of setup you’re using, you’re going to want to make sure you know the best time to water your weed plants.
Water acts as a vehicle for dissolved nutrients and minerals, being absorbed through the roots before spreading through the rest of the plant.
It also cools a plant down, fills up cells to keep the plant structurally sound, and is required for photosynthesis.
How to water weed plants
All plants, including marijuana, consist of about 80% water.
Therefore it makes sense that issues with water management could cause damage to a marijuana plant Outdoors.
A marijuana plant usually has enough water in the soil and from nature.
Depending on the quality and the structure of the soil, it can also help regulate the amount of moisture.
When growing indoors using pots, however, it is very easy to give your cannabis plants too much or too little water.
How to tell if a cannabis plant needs watering
There are no hard and fast rules when it comes to watering cannabis plants since the amount of water that you’ll need is based on the environment it’s growing in.
In general, water enough so that your soil is faintly moist, but not wet.
If the environment is very hot, the plant will use more water, but you should never give a marijuana plant more water than it can absorb.
If it seems like you are giving your plants a lot of water, don’t worry.
Cannabis plants can consume a lot of water.
A large portion of the water is also excreted from the plant through evaporation from the leaves.
Only a small amount of water remains behind and is used as building blocks.
Water also helps to absorb and transport nutrient salts and carbohydrates, enabling life.
Understanding how to water correctly can make a substantial difference in the quality of your harvest.
This guide will explain how to identify, schedule and deliver this vital ingredient for a growing cannabis plant.
The quality of the water you give your cannabis plants makes a difference.
Ideally, you could use filtered, or reverse osmosis water.
You may have some trouble finding reverse osmosis systems in a lot of hydroponics and gardening supply shops, depending on where you live.
Most growers simply use unfiltered tap water. Some places are blessed with pure tap water from municipal systems or wells.
However, most places in Europe and North America, are likely to have some impurities in their tap water, especially in large cities.
Regardless of the source of your tap water, most unfiltered tap water will contain extra minerals.
The type of minerals depends on your location, but Calcium, Sodium, and Magnesium are common.
The harder your water is, the more minerals it will contain.
There is a vast variety of potential minerals that your water could contain.
Some water companies know which minerals are in the water and can tell you if you ask, but sometimes they don’t.
While the severity of these impurities can vary, many growers crave precision in their operations, and tap water can sometimes have too many unknown variables.
If you are not using filtered reverse osmosis water, you’ll want to test your water to make sure it is suitable to feed to your cannabis plants.
In terms of its ability to carry nutrients (EC), tap water can have an EC that ranges from 0.2 to 0.8, or even higher. It can also have various pH levels, but water for feeding should be between 6.0 and 6.5.
The real issue here is that even when you take an accurate measurement, there is no way for you to know what sort of elements are in your water or the ratio at which they occur.
This means that all the extra money you’ve spent on expensive, carefully measured nutrients is for naught: the mix is instantly unbalanced by an unknown quantity of other nutrients.
In a worst-case scenario, this can cause nutrient burns or lock-outs and inhibit the growth of your plants.
You can also use rainwater, although it is not always better than some tap water.
If you collect rainwater to water your plants, store it in food-grade plastic containers to prevent any airborne contaminants from entering the supply.
Water temperature is also important. Your water should be at room temperature of around 20 degrees Celsius, 68 degrees Fahrenheit.
If it is too hot or cold, the roots could experience thermic shock.
Download our free Grow Bible for more information about watering cannabis plants.