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how much water does marijuana need to grow

To properly water a cannabis plant, it needs to be in the correct size container, or a big enough hole if it’s in the ground. If a pot is too big, the plant’s roots can’t drink water where they don’t reach. If the roots aren’t absorbing water, water will sit in soil and take a long time to evaporate, which can promote root rot and unwanted insects and fungus.

Like all plants, cannabis requires water in order to perform its basic functions. Water helps plants absorb nutrients from the soil and then moves up the plant and into the leaves, and without it, the plant can’t survive. But giving a marijuana plant the proper amount of water may be more difficult than you think.

Additionally, roots pull in oxygen as soil dries and when soil is too wet, the plant can’t pull in oxygen efficiently and essentially can’t breathe.

What is flushing?

Flushing is an important part of the marijuana growing process, when you stop giving a marijuana plant nutrients and give it straight water. This is done to flush out nutrients that may have built up in a plant during its life.

When you find the sweet spot between too wet and too dry, your plants will flourish.

How often should you water marijuana plants?

A flush can also be done to clear plants of nutrients if they have a nutrient imbalance, such as nutrient lockout, when your plants are overloaded with nutrients and unable to absorb new ones.

The best ways to tell if a weed plant needs water is to:

How much water does marijuana need to grow

Mind you, that’s just in the three watersheds the researchers looked at. According to the Press Democrat, there are more than 1 million pot plants in Mendocino alone—not counting legal ones licensed for the medical market.

The piece looks at a forthcoming study from the California Fish and Wildlife Department on three key Emerald Triangle watersheds. Using satellite imagery, the researchers found that pot cultivation had skyrocketed in the areas since 2009, rising between 75 percent and 100 percent. The three watersheds contain an average of 30,000 pot plants each, they found. (Here’s a nifty map). And they’re thirsty. According to the Press Democrat, “Researchers estimate each plant consumes 6 gallons of water a day. At that rate, the plants were siphoning off 180,000 gallons of water per day in each watershed—all together more than 160 Olympic-sized swimming pools over the average 150-day growing cycle for outdoor plants.”

And water diversions aren’t the only vice indulged in by large-scale pot growers. Last year, the North Coast Regional Water Quality Control Board listed a few others, including land-grading and dam-making that leads to stream-clogging erosion; wanton use of pesticides—most egregiously, wildlife-killing rat poison; and “discarding of trash and haphazard management of human waste.”

Of course, legal agriculture isn’t a paragon of environmental responsibility, and criminal pot farms aren’t the only operations wreaking water havoc in California. As I wrote recently, the state’s ag-heavy Central Valley is currently in the midst of sucking dry its fossil water resources, driven largely by a boom in tree nut production and a near-complete lack of regulation of groundwater pumping. The situation has gotten so dire that even big farming interests, which have for decades fought back any pumping regulations, are openly considering the possible need for smarter water rules.

Like college sophomores philosophizing over bong hits late at night, the California North Coast’s booming marijuana farms languish in the smoky haze of paradox. On the one hand, they’re hyperregulated—that is to say, illegal (with the exception of farms licensed to grow for the medical trade). On the other hand, being illegal, they’re essentially not regulated at all, as my colleague Josh Harkinson showed in a recent piece.

How much water does marijuana need to grow

When growing in composted and amended soil, the soil itself is made to slowly provide nutrients to your plant throughout its life. However, if you’re regularly watering until you get a significant amount of runoff, you’ll also be washing away some of your nutrients.

Go back to step 1. Note: If water takes a long time to come out the bottom, or if pots take longer than 5 days to dry out before the next watering, you may actually have a problem with drainage (more info below) or need to give less water at a time. If your plants are very small compared to the container they’re in, give water more sparingly until plants get bigger.

First, make sure you’re using proper cannabis nutrients for your growing medium. They should be formulated for a plant like tomatoes, and they should have a different feeding schedule for the Vegetative (Grow) and Flowering (Bloom) stage.

Not sure how to remove runoff water after watering your marijuana? Wet vacuums can be a great choice, especially if you already have one in the house. I didn’t have one, so I got Bucket Head attachment which can turn any standard 5-gallon bucket into a wet vac. You can buy one online but it’s $10-15 cheaper if you get it in person at a Home Depot. Another similar option is the Power Lid, though it’s also a bit pricey.

How to Collect Runoff Water

It’s very important to make sure that water can drain freely from the bottom of the pot, otherwise, the plant can get waterlogged and become overwatered (causing the plant to droop).

Proper watering practices will greatly help reduce the amount of salt buildup and prevent nutrition problems from occurring.

In soil, wait until the topsoil feels dry about an inch deep (up to your first knuckle – just use your finger to poke a hole in the soil and see if it feels dry).

How often do you give your cannabis water?

This is an example of great soil for growing for cannabis – rich, composted, and well-draining

In order to prevent over or under-watering, make sure you water thoroughly every time (don’t just water a tiny spot in the middle of the pot unless you plant is very small for the container). You should be getting 10-20% extra runoff water every time if you’re adding nutrients in the water. In soil, wait to water again until the top inch of the growing medium feels dry, up to your first knuckle or so. In coco coir, aim to water the plants every 1-3 days if possible, and don’t let the top completely dry out between waterings.