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Thursday November 25, 2021

By Paul Barach

Watering hose Growing

"Water = Good” is a basic equation for all life on this Earth.

That may be why many first-time growers tend to overwater their cannabis plants. After all, if “Water = Good,” then “More Water = Better,” right? Isn’t that how you fast forward that transition from “newly planted seedling” to “leafy bestower of nugs?” Not necessarily.

Whether you’re watering a cannabis plant or smoking it, moderation is always key.  Overwatering your cannabis can lead to detrimental conditions like root rot, halt its growth entirely, or even kill the plant. 

That’s why PotGuide is here with some helpful tips for watering your cannabis plant.

Dangers of Overwatering Your Cannabis Plant

Overwatering your cannabis plant submerges some of its most vital organs; the roots are like the plant’s brain and lungs. The roots can “drown” by being unable to pull enough oxygen from the surrounding soil. Too much water may also cause “root rot,” where an infection takes hold or vital nutrients are washed away. This will cause yellowed leaves and twisted or brown roots. 

Proper pH Levels for Watering Cannabis

If you want your plant to focus its energy into producing resinous buds, you’ll need to reduce distractions and stressors like improper pH levels. (pH stands for percentage of Hydrogen, and refers to how acidic or basic a solution is.)

Regular tap water works fine for watering your cannabis plants as long as you leave it out for around 24 hours so that its pH levels balance. As an added benefit, water at room temperature won’t shock your plant. Purists may want to filter their water first.

Tap water
Tap water is okay to uses as long as the pH is in a good range. photo credit

After 24 hours, use a basic testing strip to check the pH level. These strips can be ordered online or bought at hardware/home supply stores. Using a pH-down solution, you’ll need to adjust the pH level of your tap water to whatever the specific needs of your soil are.

In general, the pH level for regular soil ranges from 6.0 to 6.8. Other grow mediums may need their levels to be between 5.5 and 6.0. Your garden supplier will know the correct pH level for the medium you choose to grow in so feel free to ask, and even experienced growers will tell you that finding the right levels for a given strain might take some adjustment as you go.

Using the Right Planter

Your first pot should be large enough to let your plant grow into, with plenty of room for root expansion (moving the plant is stressful to it, and should be avoided). Pots should also have enough holes at the bottom for drainage. You don’t want water collecting at the bottom of the planter where it can oversaturate the roots. You can buy grow pots specifically for cannabis, but a standard 5-gallon plastic bucket from the hardware store and an electric drill will do the job just as well.

Adding Nutrients

Once your seedlings have started developing into plants, you’ll need to start adding nutrients. These can upset your plants if introduced too early or too rapidly, so start slow. Add about half to ¾ of the amount recommended on the product label to your water, then slowly increase over the next week or so until you reach the full recommended amount.

Nutrient burn on a cannabis plant
Too much nutrients can lead to nutrient burn.

Anything over the recommended amount can cause “nutrient burn.” You’ll know if nutrient burn is happening by the brown or yellow discolorations on your leaves. To fix it, flush the nutrients out of the soil and continue using only the recommended amount. We’ll cover flushing soil at the end. 

Watering Cannabis Seedlings

Cannabis seedlings are thirsty and can dry out quickly. Depending on the humidity and the soil you’re using, you may need to water them up to twice a day. However, only use a little water each time, preferably from a mister, to lightly dampen the soil. Too much water and you could disturb those delicate root systems.

Watering Matured Cannabis

Your watering schedule will depend on the grow medium you’re using as well as the environmental conditions. In general, you’ll want to water cannabis plants every two to three days. It’s best to water them in the early morning, or whenever your grow lights click on. This both improves nutrient absorption and reduces the risk of mold.

Larger cannabis plants can go a couple of days without being watered. In fact, it’s healthy for them to dry out a little, since this allows the roots to expand as they absorb oxygen and burrow for water. But, if your plant gets too thirsty, the stress can turn it hermaphroditic so keep an eye on it.

watering can
It is better to underwater vs. overwater. photo credit

You’ll know if your plant is thirsty if its leaves are pale and wilting. On the other hand, if you’ve overwatered your cannabis, the leaves will be dark green and claw-like as they curl and bend downwards. Neither is preferable, but underwatering is healthier for the plant than overwatering cannabis.

A good rule of thumb (or finger in this case) when it comes to watering is to poke your index finger into your grow medium. Stop at your first knuckle, or about 5 cm deep. If the soil feels dry, it’s time to water. If it’s wet, check again tomorrow. 

How To Water Cannabis

This part’s easy. Fill a watering can with your nutrient-rich, pH-balanced water, then pour it evenly over the entire surface of your grow medium. Start from the center, then work your way out to the edges. This will encourage the roots to spread out and send nutrients throughout the pot. Keep watering until you see excess water draining out the bottom. To ensure an even spread of nutrients, about 20% of the water you poured should drain back out.

If your water takes several minutes to drain out, or if your soil is still wet after 3-4 days, you probably have a drainage issue. 

Flushing Your Soil

Two weeks before you’re ready to harvest, change up your watering technique and start flushing your soil. To flush your soil, pour a healthy amount of room temperature, non-nutrient enriched water over your grow medium. Wait a couple of minutes for the water to absorb excess nutrients, then flush it again. The plant will absorb any remaining nutrients during that time. 

Someone flushing water on their cannabis plants
Many believe flushing is a crucial step to growing quality nugs. photo credit

By flushing away nutrients and only using pH-balanced, purified, room temperature water for the final two weeks, you’ll end up with better tasting nugs and less harsh smoke (or so it’s believed). Some people don’t believe in flushing, but most growers will tell you it's a necessity. 

The Wrap Up

It’s easy to get over-enthusiastic about watering cannabis when you’re first starting out. However, much like with people, moderation is key. By following our tips for watering your cannabis plant, you’ll end up with a healthy plant that’s happy to give you back some dank nugs in appreciation. 

Frequently Asked Questions

How Often Should Cannabis Plants Be Watered?

Around every 2-3 days, or twice a day if its a seedling

How Can You Fix Overwatered Cannabis Plants?

Hold off on watering again until the soil feels dry when you poke your finger into it up to the first knuckle.

Is It Better to Overwater or Underwater Cannabis Plants?

It’s better to err on the side of underwatering. If you under-water you can always add more, but if you add too much, you’ll have to wait for the soil to dry out and for the plant to process out the excess.

Any tips and tricks for properly watering your cannabis plant? Anything we missed? Share in the comments!

Photo Credit: Harry Grout (license)


Paul Barach Paul Barach

Paul Barach is a Seattle-based freelance writer, editor, and author with experience creating well-researched, edited web articles covering cannabis news, culture, history and science. Paul is a regular contributor to PotGuide and has also contributed to publications such as, SlabMechanix, Litro, and The Trek. He prefers to spend his free time outdoors and most recently hiked the Pacific Crest Trail. So far he has only fallen into the La Brea Tarpits once. You can follow him on Instagram @BarachOutdoors and stay up to date professionally through his LinkedIn page.

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