In this article, I explain the different types of water to use, how much to give your plants during the different stages of their lifecycle, equipment, and tools to use for precise watering techniques, a step-by-step guide for maintaining the correct pH levels when mixing nutrients, signs of under and over watered cannabis plants and how to fix the issue.

Table of Contents

• The Various Types of Water to Use for Watering Cannabis
• The Different Watering Stages of a Cannabis Plant’s Lifecycle
• Equipment to Make Sure You Water Cannabis Correctly
• Signs You Have Under-Watered Cannabis Plants
• Signs You Have Over-Watered Cannabis Plants
• Final Thoughts on Watering Cannabis Plants

The Various Types of Water to Use for Watering Cannabis

There will be 5 different options you can choose as a home grower when it comes to watering weed plants. Below is a short explanation of the different options that are available to a beginner-level home grower.

Soft Tap water

Tap water can be the easiest way to source water at home, and depending where you live will determine if you have soft or hard water. Soft water has an E.C level below 0.4 and will be the best option, especially for adding nutrients.

Hard Tap Water

Hard water will contain high amounts of calcium and magnesium as it percolates through deposits of limestone, and gypsum causing the E.C to be above 0.8. In the states, 85% of homes will produce hard water from the taps.

Bottled water

At your local supermarkets, you will find an entire aisle full of bottled drinking water. The E.C levels will be very low and typically the pH levels will be neutral. Using bottled water for cannabis plants is an excellent way to provide a clean and fresh source that is ideal for adding nutrients due to the low E.C.

Reverse Osmosis Water

The best way of cleaning and filtering water to remove bacteria, nitrates, and unwanted particles, whilst achieving an E.C level of zero is to use a reverse osmosis pump. It is important to know that calcium and magnesium will need to be added to R/O water before watering cannabis plants.

Rain Water

The best thing about rainwater is the fact it is free, and can always be cleaned using reverse osmosis. Not all rainwater will be clean and pure, especially when the rain water is collected from a city environment, due to the high levels of pollutants in the air.

The Different Watering Stages of a Cannabis Plant’s Lifecycle

Watering Cannabis Plants During the Seedling Stage

Germinated cannabis seeds and seedlings only need small amounts of water. Be careful not to overwater to prevent water-logged soil and dampening off where the stem becomes soft, and weak and can kill the seedlings. Damping off can be avoided by monitoring temperature and humidity and ensuring seedlings aren’t over-watered as advised by M.S.N.L.

Watering Cannabis Plants During the Vegetative Stage

Depending on the size of your pots, watering cannabis plants during 18/6 should be done systematically. It is best to only water when the soil feels slightly moist and the pots are light when picking up.

Watering Cannabis Plants During the Flowering Stage

When cannabis plants are flowering under 12 hours of lighting, they will be producing buds and need access to plenty of available nutrients in the soil. It is best to only water them when the soil is closer to dry and it is best to feed little and often. Water at the same time each day if possible.

Equipment to Make Sure You Water Cannabis Correctly

• Using a measuring jug is the most consistent way to measure.
• Using a pH pen will allow you to monitor the pH levels.
• An E.C pen will indicate how much salts are present in the water.
• Use a thermometer to aim for 68 degrees Fahrenheit according to Canna.
• pH Up or pH down is needed to carefully adjust the pH levels.

Step-by-Step Guide to Mixing Nutrients for Watering Cannabis

Step 1: Measure the amount of water you need using a measuring jug.

Step 2: Insert your pH pen and check how acidic or alkaline the solution is.

Step 3: Carefully add your nutrients following the directions on the nutrient bottle.

Step 4: Add drops of either pH Up or pH down, to aim for between 6.0 – 7.0.

Step 5: Monitor the E.C of the nutrient solution using an E.C. pen.

Knowing if you have under-watered or over-watered your cannabis plants as a beginner, will give you a huge advantage in restoring plant health, vitality, and the rate of growth. Below is a breakdown of what to look out for.

Signs You Have Under-Watered Cannabis Plants

• The plants may appear weak, and grow slowly.
• The soil will feel dry and dusty.
• Roots may have a thin and brittle characteristic.
• Stems may have a purple color.
• The leaf texture may be soft and feel thin to touch.

How to Fix an Under-Watered Cannabis Plant

• Slowly add water around the edge of the pots and saturate the soil.
• Allow the soil to wick the water.
• Wait for the plants to show signs of vitality over a 12–24-hour period.

Signs You Have Over-Watered Cannabis Plants

• The leaves will wilt downwards and claw down.
• Pots will be very heavy to lift off the ground.
• The soil will be dense and visibly water-logged.

How to Fix an Over-Watered Cannabis Plant

• Wait 24-48 hours to let the soil dry and become light and spongy.
• Use half the volume of water the next time you feed them.
• Lightly water around the edge of the pot at the same time each day.

Final Thoughts on Watering Cannabis Plants

As a beginner grower, it is always best to lightly water and keep a close eye on the plant’s appearance. Too little water and the plants will not have access to available nutrients and grow slowly and may become nutrient deficient. Too much water and the plants will wilt and droop, the soil will become heavy and wet depriving the roots of oxygen. Less is more and always be consistent and pay close attention to visual signs during each stage of the plant lifecycle!

Feature photo: Cannabis plants growing in a hydroponic system. Photo credit: Bil Sutherland.