A Beginner’s Guide for Watering Cannabis Plants

Water is an essential part of a cannabis plant’s life; however, as a beginner grower, it can be challenging to know just how much water to give them. We have all been there as first-time growers, wondering what the right amount to provide them with is. In this article, I will cover everything you need to know about watering your crop, so you can avoid under- or overwatering and grow the healthiest plants possible!

How Much Water Does a Cannabis Plant Need?

Cannabis plants will transition through different stages during their life cycle. These will be the seedling stage, the vegetation stage, and the part we all look forward to the most — the flowering stage, which is covered below.

The Seedling Stage (18/6)

This is when your germinated seeds start growing, focusing on roots and their first set of leaves, a process that lasts 14 days. Seedlings do not require much water, and it is best to leave the growing medium relatively dry to encourage roots to grow in search of moisture and air. 

• Many growers give about a quarter gallon to a 2-gallon pot every couple of days, but this can vary depending on the medium and environment.

The Vegetation Stage (18/6)

The vegetation stage is when your plants have grown their first set of leaves, and will now focus their energy on establishing a solid root base, developing a strong stem, leaves, side branches and internodes. The vegetation stage can last anywhere from 3 weeks up to 12 weeks, depending on how large you want your plants to become. During this stage, your plants will require more water than in the seedling stage.

• Around a gallon for a 4-gallon pot every 1–2 days is common, though heat, humidity, and plant size will change this.

The Flowering Stage (12/12)

Once your plants have grown to the size you want, you are now ready to start flowering them. During the flowering period, your plants will use more water than before to accommodate the amount of work they are doing, developing buds. The flowering period can last anywhere from 7-12 weeks, depending on the cultivar being grown. 

• Many growers find that around 1 gallon per 4-gallon pot every 1–2 days works well, though this will vary based on environment and plant size.

So, How Will I Know If The Pots Need Watering?

There are two simple ways for you to detect if your pots need watering.

Lifting The Pots 

The first method involves lifting the pots off the ground to determine if they feel airy and lightweight or heavy. The more water inside the growing medium, the less you’ll need to water. If the medium is light and airy, you can water it.

The Finger Test

The second method to determine the moisture level of your growing medium is to insert your finger down the side of the pot until the knuckle. If your finger feels dry, then the medium is dry and needs watering. Then again, if your finger feels wet, wait until the medium is closer to dry before watering.

The Water Source (Hard Water / Soft Water / RO Water)

There will be three different types of water that a grower can use. These are covered below, explaining the differences between them.

Hard Water

Water that contains a high concentration of dissolved minerals such as magnesium, calcium, limestone and chalk. Hard water will have an EC level above 0.8 millisiemens per centimetre (mS/cm).

Soft Water

Water that does not contain a high concentration of dissolved minerals. Soft water is usually easier to work with, but growers may need to add calcium and magnesium supplements to avoid deficiencies.

Soft water is best for watering plants and will have an EC level below 0.4 millisiemens per centimetre (mS/cm).

Reverse Osmosis Water

R/O water is created using a pump and a membrane to filter out any impurities and minerals. Reverse osmosis water is an excellent option for anyone who can only access hard water and has an EC level of 0.0 millisiemens per centimetre (mS/cm).

Understanding pH and How It Affects Nutrient Uptake and Availability

pH refers to the potential hydrogen and is a way to detect how acidic or alkaline the water source is. Cannabis plants require a specific pH range to access nutrients. If pH drifts outside the right range, your plants can’t absorb nutrients properly, even if the soil is full of them.

• Soil Grown Cannabis pH Range = 6.0 – 7.0 
• Hydroponic Cannabis pH Range = 5.5 – 6.5
• Coco Coir Cannabis pH Range = 5.5 – 6.5

Why EC Levels Are Important When Growing Cannabis Plants

EC stands for electric conductivity and refers to the strength of the water/nutrient solution and the salt content. It is best advised to use a digital EC pen when testing the electrical conductivity. If EC is too high, you risk nutrient burn; too low, and plants may starve.

The Different Ways to Water Cannabis Plants (Hand Watering vs. Automated Methods)

There are two ways to water your weed plants. The first is the traditional method of hand watering, and the other is to use an automated watering system, as explained below.

Hand Watering

• You should use a measuring jug to keep the water volume consistent.
• Hand watering each pot can be time-consuming and laborious.
• Plants are dependent on a grower to hand-water every 24 – 48 hours.

Automated Watering

• Hydroponic systems will use a pump, drip lines and dripper stakes to deliver water.
• Automated systems save a grower from daily hand watering, saving time and energy.
• Automated systems are efficient for growers with a large plant count.

How to Tell if Your Cannabis Plant Is Underwatered – Signs and Symptoms

• The pots will be light, and the leaves feel limp and dry.
• The leaf tissue may feel brittle, dry and thin.
• The leaves will not have a waxy and shiny appearance.
• Fan leaves may turn yellow and pale green.
• The growing medium will feel dry and dusty.

How to Know if Your Cannabis Plant Is Overwatered – Signs and Symptoms

• The leaves feel limp and heavy or swollen, and curl downwards shortly after watering.
• The leaves may experience tip burn at the ends.
• Some leaves may show brown edges and become dry.
• Plants may become deficient in nutrients.
• The growing medium will feel dense and waterlogged.

Common Mistakes to Avoid When Watering Your Weed Plant

Watering may sound simple enough, however, the trick is to find the right balance between dry and wet. Below are three common mistakes a first-time grower can make, and what to avoid when watering your weed plants.

Mistake #1: Overwatering Seedlings

Your seedlings will be the most delicate and sensitive to water and intense lighting during the first 2 weeks. I find that watering around the edges and using a small volume of water is best, and less is more, especially during the seedling stage.

Mistake #2: Not Checking pH Levels

Just because your water appears clean and safe to use does not always mean the pH range is optimal. Avoid watering your plants or making a nutrient solution without testing the pH level. Using a digital pH pen is the best way to determine if you have achieved the correct pH range.

Mistake #3: Using Stagnant Water

Stagnant water can contain harmful bacteria, microorganisms and potentially mold or algae if exposed to sunlight. Avoid using stagnant water and always try to use tap water that has been circulated through pipes, or fresh bottled water if possible.

My Final Thoughts on Watering Cannabis Plants

The best advice I can give you as a beginner grower is always to try to source clean and fresh water. Tap water, bottled water, or reverse osmosis water is best. Always double-check the pH levels and EC levels using digital pens available online or at your local grow shop. 

Before watering, check to see if your pots feel heavy or light when lifting, and try the finger test if you are still not sure. When in doubt, it’s safer to underwater slightly than to drown the roots. Good luck on your journey as a cannabis grower and learning about your plants and their watering requirements!

Photos by Stoney Tark.

<p>The post A Beginner’s Guide for Watering Cannabis Plants first appeared on High Times.</p>