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.
Reading tip: best temperature and humidity to grow weed
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!