With the winter months fast approaching, many growers start putting away their pH meters, pots, and fertilizers as they believe that the growing season for this year is over. Dealing with the freezing, grey, and miserable winter is bad enough, you don't want to suffer through it without some homegrown bud! Luckily there's a strategy of constant harvesting to ensure you get a steady supply all year winter long!
Outdoor growing in the winter is not really possible. Besides the obvious freezing weather, your plant will not get enough sunlight to flower. If you're aiming for that constant harvesting all year round then you will have to move production indoors.
Growing in the winter months in your indoor grow room can be even less challenging than in the summertime when the heat waves wreak havoc on your plants. However, it is vital to keep your grow room within the correct range of temperature. During the day it should be between 75 and 85 degrees Fahrenheit (25-30 degrees Celsius). Overnight, keep your temperature between 65 and 72 degrees Fahrenheit (18-22 degrees Celsius). Make sure the temperature never drops below 60 degrees Fahrenheit (15 degrees Celsius) as this can be crippling to your plants if they have to face that temperature recurrently or for long periods of times. Your plant's growth will slow to the point that it's unnoticeable, and if the temperature is still not corrected, your plant may not recover.
The other thing to watch out for concerning temperature is the not to let the difference between daytime and nighttime temperature be too big. This is especially crucial during the first 3 weeks of the flowering period. This will cause widely-spaced internodes to develop. During the first 3 weeks of flowering, aim to keep the temperature gap at not more than 5 degrees. During the rest of the flowering period the gap can be up to 18 degrees Fahrenheit (10 degrees Celsius). Hot lights will cause a significant temperature drop when they are turned off. You can avoid having a major temperature drop by keeping the lights on in the evening and off in the daytime- when temperature are higher. If daytime temperatures are still too cold you can use an electric heater or central heating to uphold sufficient temperatures. However, if you are using LED lights or other cold lights you might have to using heating at all times.
There are a few tactics besides direct heating that can keep plants warm. You can cover cold floors with insulating materials or avoid putting plants directly on the ground, as that is the coldest point.
Besides heating, winter indoor growers also face another dilemma- humidity. The relative humidity indoors is mostly lower in the winter than in summer. It can easily get below the lowest point of the optimum range for cannabis. This happens because most heating systems draw cold air in from outside and add heat without adding moisture. Because cold air cannot hold as much water vapor as warm air, the relative humidity drops.
Signs of low relative humidity is having to water your plants much more frequently. Also it can affect nutrient levels causing toxicity. Relative humidity that is low can also stunt growth by hindering the opening of the stomata. As carbon dioxide and other compounds cannot escape as with normal transpiration, symptoms of nutrient burn can appear on the leaves. Luckily managing the humidity level can be an easily and cheaply fixed with a humidifier.
Just as low humidity is a problem, problems with high relativity humidity can also occur if temperatures are too low. When air temperature decreases, the volume of water that can remain as vapour also decreases and this causes condensation to occur. This most often occurs at night when the temperature decreases. Cold and damp conditions makes the perfect breeding ground for mold and mildew. This is another problem that can be solved with a humidifier or controlling the temperature to stay slightly higher.