What Temperature Is Too Cold To Water Plants?

Milosh Potikj | April 02, 2023 | 6 MIN READ

When nurturing a garden, we often focus on sunlight, soil quality, and water quantity. However, there's a less noticed, yet equally crucial aspect of plant care: the temperature of the water we use. This seemingly small detail can have a significant impact on the health and growth of plants.

In an age where precision agriculture and home gardening are becoming more sophisticated, understanding the nuances of plant care is vital. Water temperature plays a subtle but pivotal role in determining a plant's health and growth rate.

This guide will delve into the science behind how water temperature affects plant growth. By the end, you'll not only understand the reasons behind these effects but also how to apply this knowledge practically in your garden, leading to healthier plants and a more bountiful harvest.

Ideal Water Temperature

Ideal Water Temperature

When it comes to hydroponics, the ideal water temperature is an important factor that affects plant growth. Generally speaking, most plants prefer a water temperature between 65-80 degrees Fahrenheit. However, there are always exceptions to the rule.

For example, cucumbers and tomatoes thrive in water temperatures around 60 degrees Fahrenheit, while peppers and eggplants need it to be closer to 75 degrees Fahrenheit for optimal performance.

Therefore, it is essential for hydroponic growers to do their research in order to determine the ideal water temperature for their specific plants and adjust accordingly.

Oxygen and Water Temperature

Hydroponic water temperature is an important consideration when designing your hydroponic system because the temperature of the water directly impacts the amount of dissolved oxygen in it. In a deep water culture system, this can have a direct influence on plant growth and nutrition uptake.

As temperatures rise, the amount of oxygen dissolved in the solution decreases, forcing plants to get their oxygen elsewhere. This also means that if you’re running a system with warm water, you need to be especially vigilant about maintaining enough oxygen for your plants to thrive.

Oxygen isn’t the only variable affected by hot temperatures in hydroponics; warmer waters can also promote bacterial growth, which can lead to nutrient deficiencies and other issues with plant health.

To combat these issues, some growers will use heaters or coolers to regulate their tank temperatures, as well as fans and air stones to help maximize dissolved oxygen content inside of their systems regardless of outside temperature fluctuations.

Knowing how temperatures affect your hydroponic setup makes it easier for commercial growers to meet environmental requirements and maximize benefits from their growing systems.

Root Systems and Water Temperature

Root Systems and Water Temperature

Plant roots are incredibly important for nutrient and water uptake and the overall health of a plant. They must be kept in optimal conditions to ensure their proper function and growth. One major factor in root health is the temperature of the water they are exposed to.

If the water is too cold, it can cause damage to the roots, leading to root rot. Conversely, too hot of temperatures can lead to drying out and death of soil-dwelling roots or the entire entire hydroponic system.

Roots have evolved to be shielded from heat and light beneath surfaces, making coolness ideal for their health and development. While shallow pools with well circulated oxygenated water will slow heating up, it's still important that any temperatures below 55 degrees Fahrenheit are strictly avoided as they can hamper proper root development in hydroponics systems.

Hydroponic Water Chillers

Hydroponic Water Chillers

Hydroponic water chillers are an essential component of any hydroponic system. They provide the means to cool nutrient solution and thus create an ideal environment for healthy plant growth. The power requirement and flow rate of a chiller should be carefully considered when selecting one for your hydroponic system.

Chillers are rated in horsepower (HP) and GPH (gallons per hour) or L/hr (liter per hour). Too small of a chiller will overwork it and take too much time to cool the nutrient solution, while a larger size than necessary would not be as efficient at cooling it.

How Large Of A Chiller Do You Need?

In order to calculate the size of a chiller that you need for your hydroponic system, there are several steps you must take. Firstly, you will need to cool down your hydroponic system to the desired temperature by using methods such as bagging ice or other means that will not add additional water volume to the system.

Secondly, let your system run with hydroponic lights or any other sources of heat active for one hour and measure the temperature of the chilled water at the end of this time period.

Lastly, you can subtract your desired temperature from this new water temperature reading which is then used to determine how much energy is needed to be compensated for in order to maintain the optimal levels of chill.

Sizing Your Hydroponic Water Chiller

The foundational step in determining the size of hydroponic water chillers is to measure the current temperature of your hydroponic system. In an example of a 100 gallon system, you would need to precool your system by any means necessary (ice bags, etc.) until it reaches 65°F.

Then, after turning on all devices that generate additional heat and keeping them running for one hour, you must measure the new temperature of the system. For this example we can assume that the water temperature rose to 70°F at the end of the hour.

Don't Forget The Water Pump

Keeping up with your water pump is an essential step in making sure your chiller unit runs correctly. Without it, you run the risk of your system not running efficiently and costing you more money down the line.

Not all chillers come with a built-in pump, so if yours does not have one, remember to purchase an external pump for your specific model chiller unit. It is important to pay attention to the sizing of pumps so that they can meet your needs and provide enough flow throughout the entire system.

Make sure to read your chiller manual or product page so you match the pump’s performance and throughput with that of the chiller’s exact requirements.

Hydroponic Water Heaters

Hydroponic Water Heaters

Hydroponic water heaters are essential for any hydroponic system as they help maintain a consistent temperature of the nutrient uptake. Many water heaters are submersible, meaning they go directly into your reservoir tank and continuously heat the water to a ideal temperature before automatically shutting off until it drops below that temperature.

Depending on your hydroponic system size, it's important to know the wattage rating of the heater you choose in order to correctly heat all the water quality in your set up. Additionally, if possible, placing the heater near where the nutrient solution flows from can help circulate heated water more quickly throughout your system.

Table 2 puts a numerical value on this by providing heating differential temperatures and associated system volumes along with how many watts of water heater is needed to make these temperature changes. All this information helps ensure that you get maximum efficiency out of your chosen hydroponic heater.

Sizing Your Water Heater

Sizing the right water heater for your needs is an important part of any home plumbing setup. Knowing which heater power to go with depends on several factors, such as the desired temperature change in the water and how much water you need to heat.

For example, if you have a room at 50°F and need to raise the temperature of 50 gallons of water to 68°F (a temperature change of 18°F), then you will require a 200 watt heater. It is always recommended to add an extra 25% to this wattage for a buffer, as ambient temperatures may fluctuate causing the temperature inside the tank to decline automatically or when hot water is used from it.

This means that a 250 watt heater would be optimal in this instance. Taking time to find out what size heater fits your requirements perfectly can bring balance, efficiency and cost-savings benefits in the long run.

Final Thoughts On Water Temperature

Final Thoughts On Water Temperature

In conclusion, it is vitally important to keep an eye on the temperature of your hydroponic water. A variance can have disastrous effects on your system, leading to mold and mildew growth, stagnant plant growth, and low yields. Fortunately, there are ways to raise and lower the temperature in your reservoir through water chillers or water heaters.

Finding the right equipment for your own setup can be a challenge. This is why Canada Grow Supplies offers such a wide range of options to ensure you find the perfect fit for your needs. If you're unsure or having difficulties making a choice, then don't hesitate to reach out—we'll be more than happy to assist you in finding the best product for your hydroponic system!


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