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Best Water for Cannabis

Best Water for Cannabis: Ideal Temp, Ph, EC, and PPM levels

There are many variables in growing cannabis, but what’s the best water for weed plants? Improved testing has shown that temperature, pH, EC, and PPM levels can affect your yield. Understanding these variables makes it easier to determine which type of liquid to choose.

Water is arguably the most crucial ingredient in growing marijuana. It’s involved in all parts of the life cycle, so it makes sense that higher-quality H2O improves plant health.

Read further to learn about parts per million (PPM) and electric conductivity (EC). We simplify the process of watering weed plants, giving you the knowledge without the headache. We also check out the most popular types of H2O and assess their merits and drawbacks.

Let’s dive in.

watering weed
The process of watering outdoor weed crops

Factors to consider when watering weed plants

When selecting the best water for cannabis, there are numerous factors to consider. The life-giving liquid comes in many forms and spoils growers for choice. Certain ones contribute to success, and modern technology makes them simpler to quantify.

Every grower knows their crops need it, but many don’t know how to water marijuana plants. The first step is figuring out the pH level of your medium.

Soil is either acidic or alkaline. Water and nutrients can change the pH range, improving or harming crops. Learning how to test and adjust this element can maximize your harvest.

Water quality, temperature, pH, PPM, and EC levels impact the potential for a favorable outcome. Understanding these indicators makes it easier to know how often you should water your outdoor pot plants or indoor varieties.

Water pH for weed

The potential of hydrogen (pH) indicates the acidity or alkalinity of your medium. Marijuana plants prefer slightly acidic H2O. The best pH water for cannabis plants in soil is 6.0–6.8, while hydroponic setups require 5.5–6.5.

best water ph for cannabis chart
The schema of the ideal water Ph for cannabis growing from I49

Monitor the pH in the water by using test strips or a meter. High or low readings show symptoms of nutrient deficiencies and are typically accompanied by spotty or blotchy leaves. Testing runoff H2O reveals the pH of your soil and tells you what it needs.

Testing and adjusting pH for cannabis

It’s necessary to adjust your pH to develop the best water for marijuana. Buy a pen, probe, or testing kit at a gardening outlet or online store to check your water. 

test strips for measuring water ph
An example of good test strips for measuring water Ph. Use these strips to ensure your Ph level is good.

Remember that the roots take up different nutrients at each pH stage. Incorporating a range of levels allows multiple minerals to enter the structure. Maintaining a specific pH number may be counter-productive.

If you’re testing pH in soil, invest in liquid concentrated adjusters like pH Up and pH Down. You can also substitute them for lime and soil acidifier mix. Natural options like baking soda boost the pH, while white vinegar lowers it.

Use a small dose to avoid significant fluctuations. Minerals affect the pH, so always test and adjust after adding new nutrients. If your H2O source is stable, you don’t need to check daily.

Growing weed in hydroponics requires mixing your water in a separate reservoir and testing twice. The change in pH can have an immediate effect on this medium. Let the liquid sit for an hour before trying again.

Some hydro growers elevate their weed water pH to around 7.0 during the flowering phase. Improved potassium uptake at this vital stage increases bud growth. Correct pH levels also mean less chance of mold on weed that can lead to bud rot.

Water temperature for weed

The ideal water temp for cannabis plants is around 68–73⁰F. The roots don’t absorb macro or micronutrients effectively if it’s warmer or colder.

Ideal water temp for cannabis
Best water temp for cannabis growing. It should be at least 68F up to 73F

If the water temperature rises above 73⁰F, it can reduce oxygen levels around the roots. This action attracts pathogens like pythium, also known as root rot. Cannabis plants prefer cool, well-oxygenated H2O.

Some hydro growers suggest lowering the range to 60⁰F to reduce the chance of root disease. If your water temperature for cannabis drops below 55⁰F, you run the risk of shocking your plant and slowing its growth.

The optimal air temp for growing weed is generally higher. 

The ideal humidity for growing weed is also more elevated, leading to challenges with keeping the liquid cool. You can:

  • Install cooling devices or equipment
  • Add ice or warm H2O to the medium as required
  • Place the plants in a cooler location

Cannabis water temp is essential for the effective uptake of nutrients.

PPM and EC for cannabis plants

Parts per million measures the mineral particles in the liquid. Values differ depending on the geographical area, with city taps typically containing 50–300 PPM. In the countryside, growers report high readings over 700 PPM.

Here are the requirements for each stage of the plant’s life cycle:

  • Early vegetative stage: 500–600 PPM
  • Late vegetative stage: 800–900 PPM
  • Flowering stage: 1000–1100 PPM

Optimum PPM levels may change depending on the particular strain of cannabis. If your rates are high, run the H2O through a filter. If they’re too low, harden your water by incorporating calcium and magnesium.

PPM and EC for cannabis chart
The chart showing the needed PPM and EC levels for cannabis at different stages

Adding nutrients to water changes its ability to conduct. Higher mineral concentrations improve electrical conductivity. Tap water can be soft (EC -0.4), medium (EC +0.4), or hard (EC +0.8).

Test the PPM using a Total Dissolved Solids (TDS) meter. High-quality models also rate EC and temperature levels.

Best water for cannabis plants: Choosing the ideal type

Looks can be deceiving, and all H2O is undoubtedly not the same. Consumers have a broad range of choices, and an honest assessment of the best water for weed plants is rare. We outline the relative pros and cons of each option below.

Bottled water

Bottled mineral H2O is typically marketed for personal consumption and is usually more expensive. The pH is around 7.0 with 0.4 EC, and it’s guaranteed to be clear of harmful additives.

Even the best bottled water for weed plants may contain excess nutrient concentrations that your plants don’t need. While crops need calcium and magnesium, too much can also be harmful. Excess amounts can result in a nutrient lockout that stunts growth.

Choose the lowest mineral content and adjust the pH and EC if you use this option. 

Distilled water

Making this form of H2O involves heating it to vapor and condensing the steam back into a liquid to remove impurities. Is distilled water good for weed plants?

Purified H2O doesn’t have any minerals or microorganisms, so we don’t recommend it for extended use. It needs supplemental nutrients and typically has a pH of over 7.0 and an EC reading of 0.0.

Adjust the pH and add extra calcium and magnesium to achieve +0.4 EC. Distilled water for growing weed is easy to source and allows you to maintain total control over your crops.

Reverse osmosis water

Reverse osmosis water is similar to the distilled version but contains different purity levels. It keeps most nutrients but allows some beneficial minerals through.

Make your own reverse osmosis H2O with a filter. It degrades over time but offers an excellent option for watering your cannabis plants. This liquid usually has a pH of 7.0 with EC below 0.4.

Tap water

Tap water for cannabis is the most commonly used H2O for cultivation as it’s easy to obtain and affordable. All locations have pH, mineral content, and hardness variations, but tap liquid usually has a PPM reading under 400.

This type of H2O has a pH of over 7.0 and may contain fluoride, chlorine, or lime. Some of these chemicals could harm your crops or medium. Water naturally evaporates after 24–48 hours. Let it settle before treating your plants.

Disinfectants like chloramine don’t naturally evaporate, so you may require an activated charcoal filter. Reverse osmosis and distillation also remove chlorine and fluoride.

Different local conditions mean variations in quality. Test your H2O to know what to remove and supplement. An osmosis filter helps remove harmful minerals and microorganisms, helping you produce the best water for growing weed.

Filtered water

Like bottled water, this liquid usually comes from a regular tap run through a filter. The sieve quality makes all the difference, as some remove a few contaminants while others are more comprehensive. 

Spring water and rainwater

Spring water for weed plants may sound like a fantastic idea, but it may not be the best choice. Essentially groundwater, it’s vital to find out the composition to understand its potential influence on your harvest. 

Testing the chemical and mineral content also warns you of any contamination. Spring water varies widely according to its location. This liquid has high levels of nutrients, but fungi, viruses, or bacteria could interfere with your output.

Rainwater is the best source of water for marijuana plants. Draw up a collection plan and a way to keep it clean. While generally not drinkable, rain is the purest and most natural ingredient for autoflower seeds and other variants. 

The pH is close to 7.0, while the EC rarely exceeds 0.4. Rainwater is best collected outside large cities as air pollution affects its acidity and quality.

Air conditioner water

Some growers believe the best water for cannabis plants comes from recycled air conditioning runoff, which is essentially distilled water. It has a pH over 7.0 while EC is around 0.4, depending on your unit’s age and other factors.

Use high-quality water for optimized marijuana crops

It stands to reason that the quality of your H2O impacts the quality of your cannabis. So, what pH water do weed plants need? It depends on what you’re hoping to harvest and what you’re willing to do. Here’s a brief overview of the top picks:

  • The cheapest option is tap water.
  • Distilled water for growing weed is purified and recommended if you want total control.
  • Reverse osmosis water is the most straightforward and user-friendly choice.

Buy your cannabis seeds at our online seed bank and put your newfound knowledge to the test. We have the broadest range of top-quality marijuana seeds and deliver nationwide within days.

AUTHORED BY: Cortney Bennett Ms. Bennett has more than five years of experience in the medicinal cannabis field and is currently a pharmacist at i49. Cortney continuously seeks to enhance and broaden her skills and knowledge by keeping abreast of the latest developments in the world of marijuana. Her research enables her to educate growers on what to expect, from placing their cannabis seeds in the ground to reaping a successful crop. Her enthusiasm and commitment to the weed industry are visible in her writing.

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