How to prevent heat stress in cannabis

How to prevent heat stress

Heat stress among cannabis plants can cause many problems. However, with a little patience and effort you will find that there are many ways to help plants withstand higher temperatures or recover from previous heat damage.

Before growing cannabis

One of the best things you can do to prevent heat stress is to grow the right varieties for the right climate! For indoor growers, this is less of a problem because with the right grow space design and adequate ventilation, ambient temperatures can be easily achieved. For outdoor growers, it is important to match the genetics and preferences of your variety to the geographical climate.

Warm climates: sativa/dominant sativa varieties – Paradox, Tokamak, Megaton
Cool climates: Indica/Indica dominant varieties – Baba Yaga, Atomaton, Polaris, Banshee Cleopatra

During the growth of cannabis

The damage caused by heat stress can be severe, so it is important to address it as soon as possible to avoid long-term consequences. As heat and light issues differ for indoor and outdoor growers, so do the techniques and equipment you may need.

Indoors

When growing cannabis indoors, it is ideal to maintain a comfortable indoor temperature at all times to promote rapid growth at a healthy rate. If it’s too hot for you in your grow space, it’s probably also too hot for your plants.

Solutions to heat stress among indoor growers mainly involve increasing air circulation in your growing area. This can be done with a small oscillating fan blowing over the tops of your cannabis plants, usually in combination with an exhaust system to allow effective ventilation of your grow space. However, it is important to remember that using an exhaust system can also bring cannabis aromas into your grow space. For those who want to operate more stealthily, a charcoal filter is a recommended component of the ventilation system to remove any obvious or unpleasant odours. If your plant is experiencing heat issues, you should consider:

Increasing the distance between the plants and the light source.
Improving the ventilation in your growing space, in conjunction with an oscillating fan, to ensure a more even distribution of heat throughout the growing space.

Outdoors

Growing cannabis outdoors has its fair share of complications when it comes to heat stress because, unlike indoor growers, you are not able to strictly control the climate of your growing space. Outdoor growers also have to be equally concerned about temperature drops! Generally speaking, cannabis is a fairly hardy plant that can withstand low temperatures and, as a result, outdoor varieties can usually withstand temperatures up to 50˚F without any negative side effects. However, just because they can withstand such low temperatures does not mean it is practical, as plant growth and photosynthesis will occur more slowly than in warmer temperatures.

However, there are a few useful tips, tricks and pieces of equipment that can be used to prevent heat stress as well as treat it. During a heatwave, you may have few or no options to limit the heat, but monitoring the local weather through forecasts is recommended to help you prepare – it’s better to be safe than sorry. If you know the weather conditions will be particularly hot or dry, try considering these helpful tips.

Follow a schedule of frequent and thorough watering, as it is important for plants to have enough water, especially during the hot hours of the day.
Keep the roots cool by using ceramic pots to help insulate the roots from the sun. Growers often dig a hole in the ground to put the potted plant in, which prevents the roots from getting too hot, as the ground is usually much cooler than the exposed air around it.
If the plants are exposed to too much heat, move them to a shady spot – an old sheet or tarpaulin will work well to remove most of the direct sunlight.

Heat stress problems are a common occurrence for indoor and outdoor cannabis growers, and the effects can be long-lasting and seriously affect the plants. However, there are a number of tips and tricks, as well as the use of special equipment, that can help limit the damage caused by heat stress once it has set in and can be used as a preventative measure.