Temperature

Measuring the temperature of a solution

Control your nutrient solution temperature and prevent big swings. Temperature affects plant growth, flowering, seed production and pollination.

If it’s too cold, seeds won’t germinate, cuttings won’t root, flowers won’t produce pollen. Your plants will grow slowly or stop growing altogether. Too hot, your seeds won’t germinate and cuttings won’t root. Plants can die from oxygen deficiency, or succumb to pathogens that like higher temperatures.

Most plants prefer a root zone temperature of 18 - 22 °C (65 - 72 °F). Cooler for winter crops, warmer for tropical crops.

Keep your solution at around 20ºC (68ºF) for the best oxygen content and uptake by the roots. High water temperature (above 22ºC or 72ºF) quickly reduces dissolved oxygen and increases the risk of root disease. Cold water temperature can shock roots and cause other problems.

Tips for controlling solution temperature:

• Adding water to your reservoir? Get it to the same temperature as the root zone water before you start the pumps. Rapid changes to the temperature of the solution will stress plants.
• In winter: Put a heat mat under your reservoir and/or use aquarium heaters for your nutrient.
• In summer: Use chillers.
• Protect your solution from direct sunlight: Insulate it or sink your reservoir in the ground.
• If you can’t prevent temperatures from rising too high: Lower plant stress levels by lowering the strength of your nutrient solution.
• A warm, dry environment evaporates water quickly: Evaporation can cause big problems by increasing the concentration/conductivity of the nutrient solution.
• Can’t easily lower the temperature of your growing environment? Try covering your reservoir with black-and-white plastic (white side up, black side down). This will reflect light away and help prevent evaporation.
• Reducing direct light on the solution will also slow or prevent the growth of algae and bacteria: If you’re growing indoors, be aware of the heat from plant lamps. A slight change in a light’s position can make a big difference to growth. Outdoors, or in a greenhouse, the amount of sunlight will affect the temperature of your growing environment.

Keep a close eye on the temperature of your solution

Bluelab meters measure temperature in Celcius or Fahrenheit - simply choose the units you need, or change them as you go. It's easy to read the large LCD screes, and quick to change units.

For small hydroponic sytems or beginner growers, the handy pens range or one of our portable meters will give you accurate measurements from the palm of your hand. For larger scale / commercial growing systems choose from our range of wall-mounted monitors and automatic dosing controllers.