How Much Water Do Weed Plants Need? - Happy Hydro

As a grower, one of the most crucial things to get right when growing weed plants is how much water they need.

After all, water is an essential component of a plant's life, and without the right amount, your plants could suffer.

So, how much water do weed plants need, and what are the factors that affect their watering needs?

Let's dive in.

Several factors affect how much water a cannabis plant needs. Geographical location, stage of growth, and soil type are some of the most important factors.

For example, a plant in a cooler, less humid environment might require less water than one in a warmer, more humid environment.

Similarly, plants in the early stages of growth need less water than mature plants, while plants in soil with good drainage may require more frequent watering.

How Much Water Do Weed Plants Need?

Consistent watering is essential for the health and growth of your weed plants.

But how much water do they actually need?

Well, the amount of water required by your cannabis plants depends on various factors, like the size of the plant, the size of the container, the environmental conditions, the strain, the growing medium, VPD, C02, and if the environment and humidity is optimal for the plant's health.

What should my watering frequency be?

Watering frequency and quantity may differ depending on the size of your plant and the type of soil.

In general, it's recommended to water your cannabis plants when the top 2-3 inches of soil feels dry to the touch.

While researching while writing this article, we saw a few other websites recommending you to water when the top 1 inch is dry.

That is not a good idea because the other 5-12 inches of the pot could still be completely soaked.

So we're recommending 2-3 inches, but you can double check with the weight test.

If you pick up the pot and it feels heavy, it might be too early to water. A dry pot will be much lighter than a wet one and it's often best to wait if you're unsure.

What about when transplanting?

Using a wet-dry cycle when watering your weed plants just after transplanting will cause the plant's roots to search for water and grow towards the bottom of the pot.

Drench your plants right after transplanting and let the root system drink up all the nutrients and water before the next watering. This could take anywhere from 5-10 days depending on your environmental factors and the size of drainage holes in your pots.

We recommend removing the runoff water if you're using saucers under your pots but after doing this once or twice after transplanting your roots will be very established and you can begin watering more frequently.

Is overwatering worse than underwatering?

It's important to note that over-watering is often times more harmful than underwatering. And it's much more difficult for a plant to come back from overwatering than underwatering.

Water-logged soil can lead to root rot, which can ultimately kill your plants. It does damage to the root zone and plant that can take quite a long time to recover from compared to under-watered plants.

Therefore, it's important to keep a close eye on the soil and adjust your watering routine as necessary. And be sure to avoid over-watering!

How to Water Weed Plants

Properly watering your weed plants is crucial for their growth and development. Here are the most important things to consider when growing cannabis indoors and determining how to water yours.

What should my pH levels be for marijuana plants?

One of the most important parts parts of watering cannabis plants properly is to use water that has the correct pH level.

If you grow your plants in soil, the ideal pH level is between 6.0-6.5 which is typically what tapwater and spring water comes in at.

While for soilless or hydroponic grows, the pH level should be even lower, around 5.5-6.1 and will require the use of a pH down product.

To determine the pH level of your tap water, you can use a pH measuring stick or pH measuring drops.

If your water pH is too high or too low, you can adjust it by adding some drops of pH down or pH up to reach the ideal level.

Never add pH up and pH down to the same reservoir and never let the two liquids touch as they can create a toxic gas.

What about nutrients?

Aside from pH level, adding nutrients to your water is also important. These nutrients are essential for the plant's growth and development which is directly related to the quality and yield!

Some of the most important nutrients for weed plants include nitrogen, phosphorus, and potassium. These are the "NPK" ratios that you see on the front of nutrient bottles and bags.

Make sure to follow the recommended dosage when adding nutrients to your water, as too much can cause nutrient burn and harm your plants.

Protip: use a watering can!

When watering your plants, be sure to use a watering can or a gentle stream of water to avoid damaging the plant or compacting the soil. It will also ensure an even amount of moisture retention as water gets into the plants rootzone.

Protip: avoid water on the leaves!

You should also avoid getting water on the leaves when growing indoors as the water droplets will act as little magnifying glasses that can result in your grow light actually burning the leaves.

But if you need to foliar feed your plants or spray them with pesticides for your IPM regiment you should do so either before you turn the lights on (giving the plants time to dry out) or before you turn the lights off.

Should I water at morning or night?

Watering plants in the morning has been a traditional practice, and many gardeners believe it to be the best time of day to water.

The morning is generally cooler and less windy, which reduces water evaporation and helps the soil absorb moisture better.

Watering in the morning also allows the plants to dry off before the sun gets too hot, reducing the risk of fungal diseases and sunburn. Additionally, morning watering gives the plants a fresh start for photosynthesis and growth.

However, there are some downsides to watering in the morning. If the plants are already damp from dew or rain, adding more water can lead to overhydration and root rot. Also, watering in the morning may not be feasible for people who have busy schedules or live in areas with water restrictions.

Watering plants at night or in the evening is an alternative that some gardeners find more convenient. Watering at this time allows the plants to absorb moisture during the cooler hours, reducing water loss due to evaporation.

However, watering at night may also increase the risk of fungal diseases if the plants stay wet for too long. Moreover, watering at night may attract pests such as slugs and snails that thrive in moist environments.

Ultimately, the best time to water your plants depends on several factors, including the type of plant, weather conditions, and soil type.

How to Flush Weed Plants

Flushing your weed plants is an essential process that you may need to undertake to ensure the quality and potency of your harvest.

Flushing involves providing your plants with pure, pH-balanced water to wash out excess nutrients and minerals that may have accumulated in the soil.

Growers can flush their plants if they believe that they have overfed them, but for the purpose of this article, we're discussing flushing in terms of using plain water during the last week or two of your flowering schedule.

Why do growers flush their cannabis plants?

The primary reason for flushing weed plants is to remove any built-up salts or excess nutrients that can negatively impact the quality of your final product.

If not flushed, these excess minerals can lead to harsh smoke, a chemical taste, and reduce the potency of your buds.

So how do I flush them?

To flush your plants, you need to use clean, pH-balanced water at room temperature. The amount of water required depends on the size of marijuana plants in your container or pot.

Generally, you should use three times the volume of your container size. For example, if your container holds one gallon, you should use three gallons of water to flush.

To perform a flush, first remove any accessories, such as saucers or plates, and then give your plants a thorough watering with the pH-balanced water.

You should water until you see the water coming out the bottom of the container.

Collect any runoff water and discard it.

Wait for a few minutes, and then repeat the process. This time, however, you should only water your plants with 50% of the water used in the first round.

How long does it take?

The flushing process can take anywhere from a few days to two weeks, depending on the size of your plants, the amount of nutrients in the soil, and how thorough you want to be.

During this time, you should continue to water your plants only with pH-balanced water until you are satisfied that all the excess nutrients have been washed out.

According to the experts at Leafly, you should only flush your plants when they are near maturity and ready for harvest.

Tips for Proper Watering

Proper watering is one of the most important things to keep in mind when growing weed plants. To ensure that your plants get all the necessary nutrients and water they need, there are a few tips that you should keep in mind when watering cannabis yourself.

Types of soil and size of pots

First, it's important to consider the type of soil your plants are growing in and the size of the pot they are in.

Different soil types can hold water differently, and the same goes for different pot sizes. If you're growing in a smaller pot, you'll need to water more frequently than you would in a larger pot.

Watering thoroughly and evenly

Secondly, it's important to water cannabis plants thoroughly and evenly. Make sure to water all the way around the pot to ensure that your plant's root system grows evenly.

Avoid just watering one side, which can cause uneven growth and root binding.

Don't overwater or underwater

Thirdly, it's important to avoid overwatering or underwatering your plants. Overwatering can cause root rot and other problems in healthy plants, while underwatering can cause your plants to wilt and become unhealthy.

To avoid overwatering, make sure the soil has time to dry out in between watering sessions.

To avoid underwatering, keep a close eye on your plants and make sure the soil doesn't dry out completely.

What growth stage is your cannabis plant in?

Lastly, consider the stage of growth your plants are in. As your plants grow and mature, their watering needs will change.

Seedlings and young plants will need less water than more mature plants, so it's important to adjust your watering schedule accordingly.


To summarize, we discussed the importance of watering your plants correctly to ensure their growth and health.

We talked about how often to water your plants and the different methods you can use.

We also covered the signs of overwatering and underwatering your plants and how to avoid those issues.

We also explored the reasons why you might need to flush your weed plants, including the build-up of excess nutrients or chemicals in the soil, and provided step-by-step instructions on how to perform a flush and how much water is needed.

Lastly, we provided some additional tips for proper watering, including the importance of soil type and pot size, and how to avoid overwatering or underwatering your plants.

We encourage you to apply what you've learned to your own weed growing journey.

Experiment with different watering methods and keep an eye on your plants to make sure they're healthy and thriving. Happy growing!

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