The Best Water for Growing Marijuana
High-quality water is one of the main contributors to successful horticulture. Although some plants can grow without soil, all plants need water for the oxygen and turgor pressure it provides. While most water appears clean, cannabis plants are sensitive to minerals, pollutants, and chemicals, and respond well when watered with distilled water.
Because cannabis plants are sensitive to pollutants and minerals in water, and to the volume of water they receive, all growers should familiarize themselves with the types and amounts of water they use with their cannabis crops.
With the various functions water plays in the life of a cannabis plant, it’s key that growers are prepared to supply distilled water in the correct amounts during the correct intervals to each plant.
Symptoms of Water-Related Problems
Quickly detecting and diagnosing common water-related problems is a key component to successful gardening.
Overwatered plants can develop fungus and root rot, as well as drooping and yellowing leaves. Plant’s roots naturally draw in water when variables such as pH, nutrients, humidity, water, and temperature are properly maintained, but when a plant is overwatered it cannot absorb oxygen adequately, resulting in a drowned plant.
Underwatered plants will develop dry and yellowing leaves.
Yellow, droopy and soft leaves are a sure sign of an overwatered plant. Another sign of overwatering is a slowed rate of growth.
Correct for over-watering by reducing the amount of water provided, and increasing soil drainage by adding perlite to the soil. Prevent overwatering marijuana plants by waiting until the top inch of the soil is dry to the touch between intervals.
Underwatered cannabis plants display the classic signs of dehydration: dry and wilting leaves. In the beginning, group plants of similar sizes together and plant them in pots of the same size. Placing plants in oversized pots, or with more soil than their neighbors, is likely to lead to underwatering if the amount of soil in the pot is greater than that of its neighbors.
The development of marijuana flowers depends on many environmental variables, one of them being the quality of water provided. One of the primary roles water plays in plant growth is its activity during photosynthesis and transpiration. Contaminated water travels through the whole plant, including the cells’ vacuoles, and can disrupt the plant’s development.
One of the largest factors in assessing the quality of water is determining its pH levels:
- Water that is too acidic (0 – 4.9) or too alkaline (7.0 – 14) is not suitable for plant development;
- Water’s pH balance directly determines some of the plant’s major functions like nutrient distribution and absorption, chemical changes, and microorganic activity;
- Water that is too high or too low in pH can look similar to plants affected by common nutrient-related issues like nutrient-lockout and nutrient-burn.
Hard vs. Soft Water
A primary source of hard water is found in underground wells where the water is high in mineral deposits. Hard water contains mostly elemental magnesium and calcium. While magnesium is an essential nutrient for marijuana plants, calcium can interfere with the plant’s ability to absorb other nutrients. Cannabis plants do not respond well to hard water, so expert growers recommend softening it before using it to irrigate marijuana crops.
Soft water is low in mineral deposits, with the lowest referred to as ‘very soft’ or ‘soft’. Sources of soft water typically include rain, treated water, bottled, and distilled water.
Softening Tap Water
One way of softening hard tap water is to dissolve water-softening compounds into the water. However, that isn’t the best way to soften water for marijuana plants because the softening-compounds are high in sodium. Sodium acts as a salt and collects in and around the plant’s roots. The accumulation of these salts disrupts turgor pressure, photosynthesis, and transpiration. I.e., a cannabis plant with high sodium deposit in its vacuoles will not transpire properly, which limits its ability to absorb water through the roots. Use reverse osmosis or charcoal filters in your watering system to prevent the minerals from hard water building up.
Sourcing Water for Remote Outdoor Crops
Unlike agricultural crops, marijuana growers often grow their plants in remote, hidden places where access to water is limited or non-existent. When considering a potential grow site, proximity to a water source is important. Growers can test near-by streams and rivers before using their water for irrigation. Things to test for include pH balance, mineral content, contaminants, and pollutants.
In remote growing locations where access to water is limited, growers often collect rainwater as their primary source of water.
Using City Water for Cannabis Plants
A common misconception among new cultivators is that city water is safe for cannabis plants. Although most city water qualifies as soft water, the combination of chlorine and fluoride in city water disrupts biological activity in soil and plants. Fortunately, it’s relatively easy to remove contaminants with filters or evaporation techniques.
Premium Sources of Soft Water
There are many details to consider when setting up a grow operation to supply clean water to cannabis. Distilled water is the most commercially available source of clean water. Distilled water is free of treatment chemicals and minerals, and serves as an ideal water source for cannabis development.
Large Scale Growers vs. Small Scale
A major consideration when sourcing water should be the size of the crop. Large-scale marijuana growers may stand to save money by filtering their water, especially hard water or well-water. For long-term commercial operations, the best option is to employ a water filtration system scaled to your expected crop. This is the least expensive way to get a consistent supply of high-quality water.
Another important factor when watering cannabis is the water’s temperature. Plants that receive water that’s too hot could easily die, and plants that receive water that’s too cold could go into thermal shock. The suggested water temperature for cannabis cultivation is 68° F (20° C).
Seedlings vs Developed Plants
Seedlings are sensitive to the amount of water they receive because of their small and fragile root systems. Perhaps the most common cause of seedling death in a grow operation is from excess water. Because it is so easy to overwater sensitive plants at this stage, cannabis experts recommend watering seedlings through a spray bottle.
Water is an indispensable element during plant cultivation. Cannabis plants, especially seedlings, are sensitive to the water they receive, and specifically the water’s pH, contaminants, and minerals. Underwatered plants may become droopy and dry, while overwatered plants display yellow leaves and stunted growth.
It’s key that water for cannabis plants has a pH between 5.0 – 7.0. Water too high or too low in pH disrupts the plant’s nutrient delivery and microorganic decomposition, seriously halting healthy development. To prevent shock, always provide room temperature water to cannabis plants. Most experts recommend watering seedlings with a spray bottle to prevent overwatering.
Remote outdoor crops are best watered with collected rainwater, while small-scale growers can use jugs of distilled water. Commercial growers are advised to install and utilize a water filtration system.
Watering with distilled water throughout each phase of growth is recommended, starting with the quality of water used when germinating the cannabis seed. When starting from seed, ask the people at i49 to help you find cannabis seeds. The staff at i49 know the quality of the sourced water directly contributes to the quality of the finished crop. Check out the i49 seed catalogue today!
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