What happens if plants get too hot? 420 Guide

Plants that are experiencing temperatures that are too low will have slowed growth and smaller yields. These signs can be difficult to spot if you aren't completely familiar with your plants' regular output.

You will know your plant is experiencing too much heat because the buds closest to the lights in your grow room will look stretched and bleached, or because the tips of your plant are burnt. The bud problem is a sure way of distinguishing the problem as heat rather than too much light.

Your plants that are undergoing heat stress will also start showing signs of stress through yellowing and brown spots appearing. If you haven't been watering your plant enough lately, it is more likely to experience heat stress.

Heat stress is even more damaging in the flowering stage since plant is no longer growing many new leaves. Indica-leaning strains are most prone to heat damage in the flowering stage. Heat damage during budding will reduce your yields by demolishing many of your most important leaves, while also causing buds to grow airy with ugly foxtails.

Even though the grow lights for weeds were turned off, this is what happened to an indica-leaning plant overnight after being exposed to 105°F (40°C) temperatures during a heat wave.

If flowering cannabis plants are grown under too-hot conditions for a long time, sometimes they respond by growing new buds on top of the old ones. When you see extensive growth on top of the buds closest to the grow lights, that's a sign that the grow light is too close or the temperature is too high. Some people call the new growth (which often grows in spires) "fox tails."

How To Fix Heat Problems?

To keep things cool indoors, you can install an inline fan for grow tent as well as air conditioning, or else air or water-cooled lights to ensure a lower temperature despite the light intensity. Only focus on the heat that is touching your plants, since that is the only thing that will have an effect on your plants. Exhaust fans work well to dump the heat from your garden outside - just be sure to use a carbon scrubber to make sure the smell of your garden is not launched outside with the hot air.

One simple way to fix the problem is to move the light further away from the plants. Loon-watt lights are supposed to be three feet away from your plant, air-cooled lights should be between 18 and 24 inches from your plants, and water-cooled lights can be the closest: within a foot away from your plants. If you are growing outdoors and there is a heat spell, there are a number of ways to go about cooling down your marijuana plants. For instance, micro-sprayers are a good way to have significant reductions in heat - they could lower the temperature on your plants by as much as 30 degrees Fahrenheit.

USE AIR CONDITIONING

This might seem obvious, but it's definitely a viable solution. Indoor growers have the advantage of taking complete control over the microclimate of the grow tent, provided they have access to the right equipment. This is a fairly expensive option, but can be a real life-saver if you live in areas such as Spain or the southern United States. Place an air conditioning unit in your grow tent to keep cool air circulating.

CHANGE THE POSITION/TYPE OF LIGHTING

If your plants begin to exhibit signs of heat stress, consider how close they are to the light source. If only the top fan leaves are showing symptoms, then readjust the position of your lights so that they hang further away.

If changing the position makes no difference, then you might need to change the type of light you are using. Most lights put out a fair amount of heat, and if you're growing in a confined space in a warm climate, things are going to heat up quickly. LED grow lights are a good option for growers dealing with these conditions. They put out a lot less heat than HID grow light sources; plus, they are often much cheaper to run.