The cold weather is setting in - Don’t let it settle into your grow room

Winter Is Coming - Time To Prepare Your Hydroponic Grow Room


With the dark nights closing in and temperatures outside rapidly dropping, it’s time to start thinking about indoor grow room temperatures and keeping those plants, especially the roots, feeling warm and snug. This is particularly important when growing in a hydroponic system, as unlike a soil or coco coir substrate, which offers the root zone a small amount of insulation, growing in water does not.

Plants like the air round them to be warm, as winter comes in it is best to keep your grow room round the right temperature range about: 25-28 Degrees during the lights on period for your grow room. However, when the lights are off it is best to drop the temperature a few degrees to about 18-21 degrees.

By using temperature, plants can intuitively sense when the cold months are approaching. As the nights get colder and winter starts to set in, plants begin to react to the changing weather conditions. When temperatures start to drop, we see the slowing of plant growth. Temperatures below 18 Degrees will see huge amounts of reduction in plant growth, whereas anything below 15 Degrees could see things come to a complete halt, leading to losses in time and effort invested.



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If worse comes to worst and your plants' growth is affected in this way, it can take a hefty 2-3 weeks for them to return to normal flower/fruit production. Or if you are really unlucky, the plant may not recover at all. Nobody wants to lose 2 weeks during a flowering period, especially when it has a direct impact on the size and quality of the plants. To prevent this from happening, here are some ways to ensure your plants are in peak conditions when winter finally comes.

To start with, a well-insulated grown room is critical to maintaining the temperature of the plants. Instead of placing your grow tent on a cold floor, you can use a carpet or rug as a form of insulation. Wrapping the entire tent with building insulation is also a possibility; if it works to keep your house warm, it will work to keep your plants warm!

Top Tip: Instead of sitting your plants directly onto the grow room floor, place empty pots or trays upside down and then put your plants on top of those. This gives a little bit of space between the cold floor and the bottom of the pots or hydroponic system.



Switch Lighting Periods

 Indoor HID lighting can cause problems during the summer because of the heat they produce. Use this to your advantage during the wintertime by running your ‘lights on’ period overnight when ambient temperatures are cooler, and ‘lights off’ during the daytime. The heat produced will help towards counteracting the cooler nights.

If plants are still in vegetative growth when winter takes hold, growers should also consider increasing the 'lights on' period from 18 hours to 20, 22 or even 24 hours. This will just give them a little more heat protection during the cold.

Adding more Light

Adding additional light to your set up is one of the most efficient ways you can add extra heat to your grow environment. The extra light will act as a heat generator keeping the temperature raised during harsh conditions and your plants are sure to thank you for the additional lumen output! As winter slowly creeps upon us, expanding your lighting set up is crucial to ensure you can get the most from your plants without worrying about heat.

Use Secondary Heating

With that said, the heat produced from lights is generally not enough to ensure your grow room is at the optimum temperature, so secondary heating is usually a must! Originally designed for greenhouses, Tube Heaters are small enough to be easily placed at any level within your grow room. With super low running costs, the Smart Gro Tube Heater lets out a consistent spread of heat in the surrounding air, keeping your grow room at a steady temperature.

Tube Heaters are not thermostatically controlled, so if you want that option then Oil Filled Radiators are a compact yet powerful way to establish optimum temperatures and can be used inside a grow tent or room, causing no detrimental effect to the plants.



The third option is a Fan Heater, although these should be used with caution as the dry, hot air can lower humidity, damage plants and impede growth if blowing directly at them. We recommend they should only be used outside the grow tent or room to warm up the surrounding air, or directed towards the intake. If the only option is to have it in the grow space, make sure it isn't pointing directly at the plants, or consider changing it to an Oil Filled Radiator.


Give your plants some warmth

Your plants may need some help to protect themselves from temperature spikes and really flourish to their maximum potential during the winter months. Vitalink Heat provides a great solution to that problem, a small amount can last a very long time. Using heat before the cold really sets in can help your plants develop a resistance to the cold. Use heat sparingly as overdoing it can negatively affect your plants, sticking to the recommended amounts or even slightly under can really provide some peace of mind for you during these cold months. Directions can be found on the bottle and on our website.


Look After Your Nutrients

When mixing nutrient solutions, especially in larger volumes and storing it in a water tank over several days, it's vitally important that the temperature should be kept between 18-21°C. If the temperature drops too low, the plants' roots will go into shock, slow down absorption and impede growth. Whereas too warm, the oxygen levels will decrease, plant growth will again slow, but also make them more susceptible to diseases like Pythium, aka Root Rot.

To combat this and keep pre-mixed nutrient solutions at the perfect temperature, a Water Heater should be used. Being fully submersible, they sit in the water tank and keep the solution at the pre-set temperature at all times.

Storing the nutrients effectively is imperative as poor storage can lead to damaged nutrients. If storage is too cold, the dissolved salts that make up your nutrients may crystallise and become solid. In this form, they are no longer part of the nutrient solution and remain unavailable to your plants.

In order to prevent this, make sure to store nutrients in a cool, dark place, out of direct sunlight, where temperatures sit between 10 Degrees and 19 Degrees. As a rule, never allow your nutrients to be stored at temperatures below 5 Degrees.

Top Tip: Keep an eye on your nutrient temperatures by using a waterproof Bath Thermometer that can permanently sit in the solution and give an accurate reading.


Watch Your Intake

If you're drawing outside air into your grow room, you're bringing the cold in and making it harder for your plants to stay warm. Move your intake fan so you're drawing air from indoors, making sure it’s from a different area to the grow room. There's also an additional advantage in that air being drawn from inside will not only be warmer, but also richer in CO2.

You can also use a fan speed controller on both your extraction and intake fans. During vegetative growth and early bloom, turning the fan down by a few percent will allow the warmer air to stay in the room for longer whilst still refreshing often enough for plants to thrive. This, however, might not be an option if in mid to late flower as unwanted grow room odours might require the extraction fan to be on full, therefore secondary heating, as outlined above, should still be considered.


Keep an eye on that temperature

Plants thrive in temperatures between 25-28°C during lights on, and around 18-21°C whilst lights are off, so it is important to check your temperatures regularly to ensure these conditions are consistently being hit. Simply keep an eye on temperatures and humidity in your grow room with a Digital Thermometer and that way you can work quickly if something needs addressing.

The biggest advantage of having an indoor hydroponics system is to allow you to grow all year round, but that doesn't mean your plants are safe from wintry temperatures. Taking these simple steps will ensure that you get optimum results no matter what the weather outside is.