When growing weed outdoors, you’ll need to water more often as the weather gets hotter and less often as it cools.
The best ways to tell if a weed plant needs water is to:
How much should you water marijuana plants?
If a weed plant is very dry, water will run straight through the soil and pot and quickly come out the drainage holes. If this happens, water the plant a little bit and then come back to it after 15-20 minutes and water it again, and maybe even a third time. This allows the soil to slowly absorb water until all of it is thoroughly wet.
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.
How to tell if a cannabis plant needs watering
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.
On the other hand, the location of the river can give its water unique characteristics; you’ll never find the same type of water in two different rivers. Plus, due to the content of certain minerals, it’s probably more than likely not apt for cannabis growing and you’ll need to analyze all of its contents, not just pH and EC.
In order to work using bottled mineral water you need to choose a brand that has the lowest amount of minerals, and you need to adjust the pH and EC like you would with any other type of water; it’s easy.
Water obtained from wells, springs, reservoirs and other similar sources is not entirely recommended unless you actually know its composition via a study done in your area; you need to know its mineral and chemical content. This is absolutely necessary, as it may have been contaminated using chemical insecticides or mineral fertilizer, which might render it useless for your plants. Plus, these types of waters tend to contain large amounts of bacteria, fungi, virus and parasites due to animals and possibly even people.
In order to water your plants using tap water you can do various things; let the water sit for about 24h so that some of the minerals and other components have time to fall to the end of your tank. The second thing that you can to is you can use an osmosis filter in order to clean your water and make it potable for both people and plants.
Well, reservoir, spring water etc.
In order to guarantee quality flowers and to make the most out of the nutrients used, the most important thing is to make sure that you know the type of water you’re going to use, and its contents. Secondly, you’ll need to work using specific pH and EC levels so that your plants can absorb everything they need; these levels vary depending on the phase your plants are in and depending on the strain grown. This is why you absolutely need pH and EC meters when growing cannabis, although this post is more about different types of water and how they can be used.
In order to get the highest quality rain water possible you’ll need to set up a water collection system, which will need to stay as clean as possible in order to avoid absorbing elements that could decrease the quality of the water. You can also have it set up on an impurity filter. We recommend using rain water obtained outside of cities, as the rain that falls in the city is usually contaminated as it falls through an already contaminated environment.
River water may sound like a great idea for watering your plants at first, and maybe even for drinking, although this is not recommended at all. Rivers are generally kilometers long and can have stretches in which they’re contaminated by pesticides, industrial areas or factories that use the water for residues; rivers can also contain dead animals which contaminate water due to decomposition.
Bottled Mineral Water
Reverse osmosis is a type of water that’s similar to distilled but not quite as pure, as it doesn’t eliminate 100% of all minerals (lime, chlorine etc.) and other impurities in water, but it’s incredibly similar and you can get it from your own type by simply getting a decent osmosis filter and setting it up. Depending on the filter and how long it’s been there for, osmosis filters tend to produce less than 0.4 EC and around 7.0 PH, so you can drink it if you want and you can use it to water your plants without needing to modify it at all.
Air conditioner water is taken from your very own air conditioner, and you can use this water when it comes to watering your cannabis plants, as it’s essentially distilled water, although we always recommend using an EC meter; depending on how old the AC unit is or its design, it may actually have an EC of 0.4 rather than 0.0. Its pH is usually over 7.0.
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.
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.
As the legalization of marijuana spreads across many U.S. states, pot growers have more questions about the water that goes into growing legal weed, specifically how contaminants in that water might affect the overall health of the plant. Recreational marijuana is now legal on the entire west coast, in addition to Alaska, Maine, Colorado, and Massachusetts, and medical Marijuana and CBD oil are available in many more. As more retailers get into the legal weed game, the more growers (and frankly, run of the mill gardeners) are questioning the long-term impact that chemicals used to treat tap water have on soil and the plants growing in it.
Avoid Chlorine Toxicity
Depending on where someone is living and growing, they’re more likely to have excess chloride in their tap water in areas that are dry regions, irrigated, coastal areas, and/or in areas with heavy winter snow that treat their roads with salt.
Chieng recommends watering recreationals with rain water when possible and only using tap water to “supplement” when reserves are low or rainfall is scarce. One option is to get a rain barrel. They collect precipitation from a house’s downspout and are sold in the gardening section of the local hardware or home improvement store. Another strategy that’s been employed by organic gardeners is to leave a bucket of tap water in an open container for a day or two. This at least allows the chlorine to dissipate, though it’s important to note that it does not have the same effect on chloramine.
Killing The Microbial Growth
Then there’s the concern over what effects residual chlorine has on the microfauna in soil. While University of British Columbia soil scientist Sietan Chieng notes that there are so many variables of what’s affecting soil that it may be nearly impossible to tell what effects chlorine and chloramine have on the microorganisms in soil, others note that chlorine kills many microbes that are doing the work of releasing the nutrients in soil that plants depend on for healthy growth.
Microbial growth is necessary to break down organic material in the soil and make nutrients available to plants and trees. So, if someone is using tap water to water in their garden or cash cow cannabis crop, there’s bound to be some chlorine in it.