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growing marijuana in water

Conversely, if a container is too small, the roots won’t be able to stretch out, which can stunt the growth of a plant. Less soil also meant you’ll need to water the plant all the time, which will add labor.

The final flush should occur for a week or so before you cut down weed plants for harvesting. Water your plants with the same amount as you normally would, but only with water. This will force the plant to use the nutrients stored within it—if its nutrient reserves are not used or broken down, it could affect the quality of your harvested buds.

Here are some tried-and-true tips to keep your weed plants healthy and properly hydrated.

What is flushing?

A common mistake first-time growers make is to overwater marijuana plants. A cycle of wet and dry is healthy and necessary for the roots of a plant to grow out and reach deeper into the soil.

If growing in amended organic soil, it is not recommended to flush plants. This is because the soil already holds all the nutrients the plant needs to thrive, and by flooding the soil you can wash away and damage the complex ecosystem that you’ve worked hard to develop.

An under-watered marijuana plant looks droopy and weak, with yellow or brown leaves; there is no strength in the leaves and they look lifeless.

Flushing marijuana plants before harvest

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.

You want to water a plant enough to soak all the soil in the pot. Water should pool up on the surface of the soil when you’re watering, and come out the drainage holes in the bottom of the pot after a couple seconds. If water sits on the surface of the soil, that means it’s too wet and doesn’t need more water.

Growing marijuana in water

There are contaminants in the water that could be affecting marijuana growth.

Killing The Microbial Growth

What effects do those chemicals have on plants in general and marijuana specifically? Plants need some chloride, which is a micronutrient, to grow, but too much of it — what’s called “chlorine toxicity” — can build up in a plant and result in browning, yellowing, or scorched-looking leaves. It can even cause leaves to fall off the plant entirely, which, in the case of a budding cannabis, of course, sort of destroys the point of growing it at all. And according to the University of Maryland Extension’s College of Agriculture and Natural Resources, “chlorine toxicity can result from air pollution in the form of chlorine gas, or from excess chloride in the soil.” But guess how that chloride gets into soil? Yuppers, by way of water — through swimming pool runoff, irrigation, salts that are added to streets when it snows, and of course, tap water.

Avoid Chlorine Toxicity

As water makes its way through the local water treatment plant, it’s treated with chlorine and chloramine to kill dangerous bacteria, but unfortunately, not all of those chemicals get filtered out before that water hits our homes. The concern among some organic farmers is that those chemicals are killing off important microbes.