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When To Water Cannabis Plants?

Created by
JoshuaHolt JoshuaHolt
Added 13 December 2021

Watering

The cannabis plant loves water more than anything. Water is one element that determines how the plant performs. 

But, overwatering is the quickest way to kill a plant. Just because water is essential doesn’t mean you flood the plants. 

On the other hand, underwatering will also kill the plant. 

To grow a healthy plant with potent buds, you must learn how and when to water it and when you should leave it alone. Understanding your plant's water needs is a simple yet essential step that helps you become a pro at growing terrific buds.

And while the timing of watering your cannabis plant may look easy, you need to be meticulous with your approach. For most newbie cannabis growers, overwatering that damages the plant is expected. Underwatering, not so much. 

You must also understand that your watering timing depends on various factors, like the plant's growth, light intensity, pot size, and medium. Plus, water source varies from region to region, further impacting your plant's watering cycle.

For the same reason, you must avoid vague watering schedules available on the internet — they may not work for your cannabis plant and conditions. In addition, some strains may require more water, while others may do well with light watering. 

Simply put, you must stick to what works for you, which comes only with experience. However, we will provide important tips, so you don’t fail, even if it’s your first time growing cannabis. 

In this guide, we show you how to understand what your plant is trying to tell you and how to water cannabis plants the right way.

Water Source to Grow Cannabis

Understanding your water source is crucial because even the best nutrient combos for your specific plant strain can be thrown off by the minerals present in your water source. So, let's dive deep into your water source (not literally!).

For a healthy cannabis plant, the water must be pH-balanced, with low mineral ppm (few contaminants), no biological pollutants, and an ideal temperature of around 21°C. You must also consider the cost, availability, environmental impact, and ease of collection.

Let's look at some of the most common ideal water sources for cannabis.

Ideal Water Sources

Tap Water

Using unfiltered tap water is the easiest option for most cannabis growers, and usually, this is enough to grow a healthy plant. However, there are some things that you must consider.

If you live away from the city, you're more likely to get tap water that's good to use without any kind of treatment. But if you live in a city, your tap water may contain various contaminants that must be rectified. The best way to remove chlorine and make the water usable is to let the water sit in sunlight for at least 24-48 hours. Then, balance the pH and water the plants. 

Tap water pH can vary everywhere. It may either be higher or lower than ideal, but this issue is not difficult to address. You can sort the pH balance with a pH balancing solution. We also recommend investing in a pH meter for the same.

If you're still skeptical about using tap water, you can even invest in a simple household filter to increase the purity of the water. Reverse osmosis water filtration systems are good, but they are expensive, so we don't recommend them.

Collected Water

Natural water

Whether you collect rainwater or use water from a natural source, collected water is another cheap and sustainable way to water your cannabis plant.

Collected water from a natural source, like a river or lake, can vary wildly in contaminants and pH balance. So, you must test it before using it on your cannabis plant. It could be perfectly balanced for your plant or be full of biological contaminants or farm runoff.

On the other hand, rainwater is a better option as it is relatively free of contaminants. Just ensure you store rainwater in tanks that do not harbor biological growth. Plus, it is free and has no environmental impact — that's an added benefit.

Bottled Water

Bottled water

Many growers also use bottled water to grow their plants, but we don't recommend this. Yes, it is easy, well balanced, and pure, but the environmental impact of plastic waste is not worth it.

Figure out which water source works best for you and treat it well, so it's ready to be used for your plant.

Right Time to Water Your Cannabis Plant

You've figured out the right source, but the timing can be a bit tricky. And there's a lot of conflicting opinions on the internet about the timing. For example, some growers prefer watering the plants every few days, while others water them daily.

We recommend you observe your plant to know when to water it. Some factors include:

Soil Medium

dry soil

If you water the plant every day, you will drown the roots, and if you wait for the plant to wilt before watering, you will trigger nutrient deficiencies — both situations can cause stunted growth and poor yields.

Instead, you should let the soil dry between waterings, offering the perfect water balance for your plant. Plus, it will be better for the roots' health by giving them ample time to breathe.

Understanding the right time to water a soil-based cannabis plant is not hard. First, you simply have to test the soil and water when dry. In addition, including substances like perlite that encourages aeration will help the water evaporate faster. 

Pot Size

Pot size

The size of the pot is yet another factor that tells you the right time to water the plants. For instance, if you have a massive pot with a lot of growing medium, it takes longer for the water to evaporate, whereas smaller pots with little growing medium will be faster. Typically, you will have to water less if your pot size is bigger than 3 gallons, whereas a smaller pot will demand more water frequently. 

Environmental Factors

Humidity levels

The environment around the plant is the most important. Even if you use appropriate pot sizes and water the plants on time, the temperatures and humidity levels can affect evaporation. For instance, it takes longer for the water to evaporate if the humidity is too high, even if the size of the pot is small. 

Stage

Humidity

Temperature

   

Seedling 

High 60-70%

20-25°C

Vegetative 

Moderate 40-70%

22-28°C

Flowering 

Low 40-50%

20-26°C

Late Flowering 

Very low 30-40%

18-25°C

 

Conversely, low humidity levels will help the water evaporate faster. Higher temps will also encourage transpiration, whereas lower temps will slow down the process of evaporation. As the plant grows, you will need to reduce the humidity levels to ensure they grow well. 

Garden Beds

The right time to water your cannabis plant in a garden bed is an entirely different ball game and somewhat tricky. The roots tend to go deeper in a garden bed, and the topsoil may not indicate the overall water content.

So, what you can do instead is simply water the plant regularly unless the topsoil is wet. Garden beds tend to have better drainage, so the water gets soaked deeper into the soil. As long as you are not drowning the roots, the ground will even out the water adequately.

Hydroponic Systems

Most hydroponic cannabis systems require the roots to be exposed to water regularly — some systems submerge the roots in water at all times, and others do so intermittently. Thus, speaking of watering your cannabis in a hydroponic system seems a little redundant. 

Still, you must keep an eye on your plant. Hydroponic systems offer you the luxury to see the roots clearly, which can be a terrific insight into the plant's health. 

Just follow the hydroponic system's water recommendations, and your plant will grow healthy.

Watering Your Cannabis Plant at Night

Light + watering

We do not recommend you water your cannabis plant at night. It does more harm than good. 

Plants require water and nutrients during the day because it’s when they use most of their energy. And plants lose a lot of water due to heat and light, so they are also more likely to absorb water during the day. 

Plus, if the plants are wet during the cooler night periods, they become vulnerable to infestation and mold. 

When you water your cannabis plant in the day, the plant has ample food and water to last the night, and the soil also does not remain damp during the night. Therefore, it is the safer, healthier option for your plant.

Ideal Time to Flush the Medium

Flushing

Many growers recommend flushing the medium regularly, but it may not be required in most cases. Flushing essentially drenches the substrate in pure, pH-balanced water to wash out the accumulated salts.

You don't need to flush the medium unless you have overfed or drowned your plant. Flush only if the plant experiences a nutrient lockout or burn.

Many growers flush the plants to remove excess salt build-up, but you must do this only during the last two weeks of flowering. Flushing also improves the taste (there’s no solid evidence to prove this), so you can flush the plants with more water during the final few weeks of flowering. 

Tips for Watering Your Plant for Beginners

Now that you have figured out your plant's water source and requirements, you can start with your watering regimen. Here are a few tips that will help you improve your watering regimen.

Water When the Medium is Dry

The cannabis plant is used to varying water levels, so you need to water less and let the soil dry for a bit to give the roots some room to breathe. 

Insert your finger into the soil medium to check if the plants need water. If there's excessive water, your finger will be wet. On the other hand, if the medium is dehydrated, it indicates that it needs more water. Your finger should be moist rather than being too try or wet.

Ensure Adequate Drainage

Along the same lines, a lot of water can be harmful so ensure the medium has enough drainage. Soil and some other mediums tend to hold a lot of water, leading to oxygen deprivation, rot, and infections in the root. Therefore, mix some perlite, vermiculite, and other aerating substances in your growing medium. 

We recommend investing in suitable trays to hold excess drainage and avoid a mess. 

Monitor the pH Regularly 

We can't stress this enough — the proper pH balance is crucial for your plant's health. Invest in a pH meter and pH balancing solution.

Always check the pH before watering your plants unless you're growing the plants organically. Also, test the runoff water pH — it gives you an accurate depiction of the pH in the soil. 

Pot Weight

Pot weight

Lift your pots to check whether they are light or heavy. If the pots are super light, it's time to water the plants. However, if the pots are heavy, avoid watering for a couple of days until the pots are light again.

Water Temperature

Never water the plants with freezing or boiling water. Instead, always use room temperature water or lukewarm water to maintain oxygen levels in the root zone.

Do Not Water When the Lights are Off

No matter what you read on the internet, it is never a good idea to water the plants when the lights are off. It can increase the humidity levels and create an oxygen balance while causing the root zone temperatures to drop erratically. In addition, the plants tend to use the water more when the lights are on. Therefore water the plants just as you switch on the lights. Ensure that you don't water the leaves since a combination of water and light can burn them

Ideal Watering for Various Plant Stages

The plant goes through various stages during its life, so its water requires change. In addition, different stages of the development require varying water levels, and you must recognize this for healthy growth and potent buds. 

Seedling Stage

Seedling stage

Seedlings are pretty fragile, so overwatering them can kill them. A moist environment is ideal for seedings, not a soaked one. Plus, cannabis seedlings thrive in an ideal humidity of around 70%.

We recommend you use a propagator to water the seedlings; this would help you strike a balance between soil that's sufficiently humid and dry. You can also use a hydrometer to keep the humidity levels in check. 

Vegetative Stage

Vegetative stage

Your cannabis plant will be thirstier during the vegetative stage and will assume 50% of its final mass, so you must water it right to help it grow properly. Generally, you must water the plant 1 to 3 times a week for optimal growth, but use this only as a guide. Then, consider the above points and listen to the plant for the final watering regimen.

Flowering Stage

Flowering stage

The flowering stage is exciting, but you must not hurry. Watering at this stage is crucial, and your plant will need more water, too.

So, listen to the plant and water it accordingly, and don't forget to mix bloom-specific nutrients and boosters in the water. However, avoid overwatering the plant at any cost as it can cause nutrient burn and affect your buds.

Recognizing Incorrect Watering

We have been talking about overwatering and underwatering, but how do you recognize this? 

Underwatering the Cannabis Plant

If you underwater your plant, it can stunt your plant's growth. Here's how you recognize underwatering:

  • Drooping leaves
  • Lackluster green color
  • Dry soil
  • Yellow, brown, or crisp leaves

Underwatering is not the end of the plant, though, as long as you take proper measures to rectify it. Here's how you can solve the underwatering situation:

  • Water the plant 
  • Drench the entire substrate in water so that you get 10% to 20% runoff water at the bottom

You'll notice the plant perk up fairly quickly.

Overwatering the Cannabis Plant

On the other hand, overwatering can be worse and sometimes even fatal for the plant. Here's how you can recognize overwatering:

  • Deep green, oversaturated coloration
  • Oversaturated, wet soil
  • Drooping leaves with discoloration from the bottom upward

Still, you can fix overwatering if you act quickly. Follow these tips to solve overwatering:

  • Give the plant time to dry out until it looks normal again
  • Repot the plant and cut off any rotten roots
  • If you see leaves dying off, it could be a sign of root rot, so you must cut the rotten leaves and replant the plant in fresh soil

The plant shall start looking healthier soon. After that, water less than you usually do to be on the safe side.

It can be a problem if your growing medium doesn't retain enough water or drains too much water. For example, over-watering can cause water evaporation to be too slow that further causes other issues. 

Due to excessive water around the root zone, the leaves will increase transpiration to compensate or balance the equation. Since the plant will have to find its own way to transport excess water either through the root zone or the foliage, it causes stunted growth and jeopardizes the yields.

So is it a good idea to provide less water, so the plan doesn't have to struggle? No — just like over-watering causes problems, under-watering comes with its own issues. When the plant lacks water, it is not happy.

Simply put, both over-watering and under-watering exhibit similar symptoms. Excess water around the root zones will prevent the plants from absorbing enough nutrients. This means that you water only when the growing medium is dry, or the pot is light.

In addition, it is important not to feed icy water. Similarly, do not feed hot water unless you want to cook the root zone! Always feed lukewarm water to prevent extreme conditions. For example, cold or wet roots invite anaerobic bacteria that infect and kill the plants. 

However, there should be enough oxygen in the root zone for the plants to do well, so it is important to choose good pots to keep the root zone healthy. One reason why many growers use fabric pots is that it encourages air circulation.

Over-feeding

Overfeeding

Anything in excess can be detrimental to the cannabis plant. Like overwatering, overfeeding or feeding the plant with extremely strong nutrient solutions can cause toxicity and excessive mineral build-up, resulting in a lockout.

Overfeeding usually results in burned tips of the leaves. Do not confuse this with light burn because it destroys the entire leaf, whereas overfeeding typically burns only the tips initially. Keep an eye on the pH to prevent overfeeding. If you notice problems due to overfeeding, flushing the plants will reduce the nutrient lockout and balance the pH levels again.

Tips to Water Your Cannabis When You're Away

Cannabis is a peculiar plant that requires a lot of attention. It's almost like your cat, except it doesn't knock over your favorite vase all the time. 

Assuming you don't want to invest in high-tech systems, here are a few ways you can ensure proper watering of your plant even when you are away.

Drip Irrigation System

A drip system is easy to set up and can sometimes even be free. You can either use pipes or plastic bottles with holes drilled into them to provide a constant, manageable water supply to the plant's roots. 

The only downside with a drip irrigation system that uses pipes directly attached to the tap is that it can flood your entire culture in case of a mishap. We even recommend using the drip irrigation method to water your cannabis plant even when you're home — it will take a lot of labor off your shoulders. 

Automatic Watering Stakes

If you don't mind spending a little money, you can invest in automatic watering stakes. These are easy and rick free. 

Here, the stakes are placed in the soil and have a wick leading to the water reservoir. As the roots absorb water from the stakes, reverse osmosis in the wick pulls more water from the reservoir.

Your Friends

Friends in need are friends indeed. So, ask your friend to look after your cannabis plant, and share a few buds with them in return! Just ensure they understand the importance of watering your cannabis plant on time. Keep this article handy to be on the safe side.

Summary: When To Water Cannabis Plants

Watering your cannabis is easy, but it is not as simple as just pouring water. It takes a little more than that.

But if you properly water your plant, you can ensure your plant's health and enjoy great buds!

The main takeaway is to observe your plant and medium. If the soil looks damp and the plant looks healthy, you're doing good. Don't fixate on schedule. 

Lastly, listen to your plant. It communicates more than you would think. And remember the mantra, Less is More.








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