Water Temperature for Cannabis Plants

Water’s essential for cannabis growth–plants need water,that's a given. But the quality of that water can turn your yields into either the stuff of dreams or…”a learning experience”. There are ideal conditions of PH, mineral content, and water temperature for cannabis plants that need to be met for maximum health and maximum quantity of flower, so watering plants is deeper than you might think! Pun intended. 

Of all these qualities, water temperature tends to be the most overlooked. For soil growers, water usually comes out room temperature from a tap or distilled jug, and it's not often you'll see a hydroponic grower decide to load their tank with crushed ice. But to understand why this point of quality in your H2O can't go completely under the radar, we'll need to take a look at water's effects on your plants beyond what's on the surface.

What does water really do for cannabis?

Physical and chemical reactions are taking place on a cellular level when you water! Understanding what watering actually does for your crops is key to keeping up with what needs to be done on your end–so take this “water is wet” kind of info seriously.  

Physical Effects

Plants don’t have bones or exoskeletons like animals do. What holds them up structurally are their cell walls– protective membranes that are unique to plants and fungi. These cell walls in cannabis are comparable to water balloons. Given an excess of water, they’ll burst, leading to limp, soggy structures that can’t be restored. Given too little water, they’ll be shriveled until eventually being totally unable to take in any water at all without rupturing. 

But at the perfect amount, you’ll have elastic, resilient structures that: 

• Keep leaves fully unfurled to absorb maximum light. Photosynthesis is key to growth of all structures, including buds and trichomes, and is essential to the vitality of your cannabis. Some plants grow well in the dark. You're not going to get the therapeutic effects you seek from any of them! Water and light go together in your cannabis like peanut butter and chocolate. 

• Fuel vegetation and bud growth. Remember middle school biology? The mitochondria is the power house of the cell and so on? That's when you learned about mitosis–how cells divide so that an organism can grow. Your cannabis is no different! But with cell walls having the unique need for a full "body" of water, this division will be totally halted when your cannabis isn't hydrated, and as you're already aware, the cells will die. Once they go, they can't come back, so be sure to keep an eye out for the signs of over watering and underwatering. We'll discuss those later on in this article, so keep reading!

• Add anchorage to root systems. Whether your're growing indoors, outdoors, hydroponically, or in soil –your roots need to be long, strong, and down to get their grounding on. Outdoors, wind, rain, and the odd animal will push your ganja around. Indoors, stalks still need their ground crew to be as stable as they are absorbent so they can focus on growing upwards, no matter what medium they're planted in. Roots need to be the perfect amount of flexible while growing, conductive while grown, and stabilizing as the plant's vegetation gets bigger and better. 

Transpiration is another physical phenomenon that requires proper intake of water and proper water temperature for cannabis plants. Specialized cells on your cannabis' leaves called 'stomata' are the exchange point for oxygen and carbon dioxide, as well as a small amount of water vapor, which becomes a larger (comparatively) amount in cases of mild overwatering. You can think of them as tiny nostrils that line every leaf. For transpiration to take place as needed, each stoma must be adequately pressurized by, you guessed it, water content in its cells. If these cells are too compressed by dryness or blown out by an overabundance of water, the problems with your plants will continue to snowball as interconnected systems begin to go down one after the other. Your weed needs to breathe!

Chemical effects

Now that we know what's going on with water and weed on a microscopic level, let's go down even further to the atomic scale. 

Although in the wild, ancient and modern day "feral" cannabis derived nutrients from bacteria breaking down dead matter near it, growers like you are raising a refined, higher quality version of that same plant. That means waiting for a mouse to die nearby and go through the cycles of breaking down and being reclaimed isn't your cannabis' only option for nutrient intake. Our way is faster, and less smelly for a reason–Lotus Nutrients uses all water-soluble compounds that all make their way into your weed with ease. The only exceptions are the extracts used for helpful microbe feeding. 

Point here is that water functions as an indispensable nutrient-relaying medium for domesticated cannabis, especially when your aim is to grow bigger, stickier buds to harvest. 

Without the right water temperature, PH, and PPM, these nutrients won't absorb as designed, leaving your future yields compromised at best, your plants dead at worst. And what makes up the water is just as important as what's in it! 

Water is made of two parts Hydrogen, one part Oxygen. And both of these elements are as much macronutrients as Nitrogen and Potassium! 

You've never seen either element on a nutrient ingredient list, including ours for a few reasons. Oxides, which you'll know as any chemical name ending in 'ide' like potassium chloride, are chemical compounds that easily dissolve in water thanks to bonding with oxygen. So technically you do see oxygen in your list, just not by itself. Getting this gas into pure dry form is no easy feat, and with hydrogen…our chemical engineers weren't too keen on trying too hard to split it into anything else. 

The biggest reason however? You give your plants these elements whenever you water! Extra aeration can be provided to sickly roots by further diluting drugstore hydrogen peroxide (H202) into water, but by and large, your plants won't need any more Hydrogen or Oxygen than is in their water rations. 

Oxygen is an essential part of respiration–how plants produce oxygen in a breathable form for us by breaking down carbon dioxide. Like transpiration, this process also takes place through the stomata, but rather than moving water around and out, respiration is a necessary part of metabolizing glucose in addition to releasing the byproduct of the Carbon plants need. Carbon is a third macronutrient that tends not to get counted as it flows freely in the air as CO2, and growing plants in the total vacuum of space is not what most cannabis cultivators have in mind. 

Hydrogen as a macronutrient is another building block element. The chains of amino acids that drive cell growth are spurred on by hydrogen ions (multiple atoms bonded together) 'donating' their electrons to other compounds. This exchange prompts an entire nanoscopic assembly line that turns glucose and nutrients into new cells! 

What is the ideal water temperature for cannabis plants?

Cannabis can be finicky about water temperature, more so than we'd like to think! Most people know not to pour whatever's leftover from a boiled tea kettle over their grow (we hope), but pouring in water fresh from the filter in the fridge, or straight out of a forgotten car bottle on a sunny spring day can also be ill-advised!

Ideal temperature for soil

When watering cannabis grown in soil, your ideal temperature is between 65 and 73 degrees Fahrenheit. Water that's higher in temperature, like your pasta rinse, or that excess from the summer bird bath, will be lower in oxygen. Roots will struggle more to take in what they need and pass it along.  Additionally, the environment that this lower oxygen creates, as well as the added warmth, will increase the growth of microbes–not all of which are 420 friendly. If you're growing inside in a tent, repeatedly adding higher temperature water will raise both temperature and humidity inside, making growth and transpiration more difficult, so keeping it room temp or just a bit below is ideal.

If cold water's so great, why isn't iced water better? Simple! Your cannabis is not a member of the Polar Bear Club! If the water you add is too much colder than the ideal range, your roots will be shocked. Just like a cold human, they'll contract their tissues and shut down for a bit. Too much of this will lead to stress, and even nutrient lockout!

Ideal temperature for hydroponics

For plants living in water full time, the best temperature shifts down slightly to 63-68 degrees. Because the roots are constantly saturated, it's better to have a cooler temperature work with your aeration system to keep everything oxygenated and unslimey. Hydroponic chronic is subject to the same microbes and stresses with too-hot and too-cold water as soil is–though the larger volume of water means that temperature changes need to be taken seriously. 

A water heater (like the kind you'd see in an aquarium) or an external water chilling system may be necessary depending on where you're located, and what kind of structure your hydroponics are inside. 

It's not advisable to add very hot water or ice to your hydroponics to adjust the temperature due to the possibility of shock. If your system needs an immediate change, sub in PH tested water closer to the right temperature after bailing some of the original water out. 

How should I measure the temperature of my water? 

While it's important to invest in a thermometer for your hydroponic grows, your soil can be a little more relaxed. Most people instinctively recognize the range of temperatures soil favors just by touch–cool, like a pool, but not refreshingly cold like a refrigerated beverage. So long as you neither shiver, nor want to shower in it, you'll probably be fine, but if you want to make absolutely certain–a thermometer, bucket, and lifting with your legs will be easy additions to your watering routine. 

Want more info on watering? Watch this space, and check out our YouTube channel for FAQ's and interviews!