How To Protect Autoflower Strains From Heat Stress

In this article you will discover the best ways to protect your outdoor autoflowering crop from heat stress, what can be done and our top tips to keep your plants cool this Summer.
03 April 2020
4 min read
How To Protect Autoflower Strains From Heat Stress

  • 1. What are the signs of heat stress
  • 2. Providing shade
  • 3. Polytunnels
  • 4. Use white pots
  • 5. Top tips on protecting your cannabis plants
  • 6. In conclusion

Sometimes things such as soaring outside temperatures can be out of our hands, forcing our plants to take on the elements. Heat stress can cause Cannabis plants many issues, so in this article we explain the best ways to protect your plants, our top tips and our best strains to grow for those who live in a hot climate.

1. What Are The Signs of Heat Stress

In an ideal scenario, it is advised to grow autoflowering Cannabis indoors at 24 degrees Celsius, with a humidity level of 75% reducing down to 30% during the flowering period. When growing autoflowering plants outdoors, temperatures in Southern Spain, California, and other tropical climates can exceed daytime temperatures of 30-40 degrees on average in the Summer months. It is also conveniently the peak season to grow autoflowering cultivars in any part of the world. A perfect option of an autoflowering strain for all climates without any doubts is Orange Sherbet Auto, she performs extremely well especially in Mediterranean, California and South America leaving you no options to fail.

As Cannabis plants transpire water through their roots or foliage, when there is an unexpected spike in temperature the outcome will be a reduction in the amount of water the plant consumes. As a defense mechanism, Cannabis plants will reduce the amount of direct sunlight they receive, resulting in a drop in photosynthesis, the conversion of sugars and the uptake of nutrients.


How To Protect Autoflower Strains From Heat Stress: Signs

Signs Of Heat Stress Of Autoflowering Cannabis Plant

2. Providing Shade

Just because Cannabis plants will not be receiving direct sunlight, it does not mean they are not getting plenty of light, in accordance with CO2 and nutrients. It is much better to provide shade for your plants and allow them to adapt than stress them by intense sunlight. It's important to choose strains that can be resistant, adapting well to extreme conditions, like Original Auto Jack Herer or Purple Lemonade. They perform extremely well indoors or outdoors and can endure heat stress with no issues. Some other cultivars may be more sensitive and need assistance with keeping cooler.

Now, this does not mean you have to shade your plants the entire day, only during 12-4pm when the daytime temperatures are at their most brutal. There are a few different ways to shade your plants and it can be something as simple as a large mosquito net, or very thin fabric.

3. Polytunnels

Building a short-sized polytunnel to keep your autoflowering plants inside, is a wonderful way to grow autos all year around. Building the tunnel is half of the fun than planting your organic crops, inside is where the magic really happens. On the basis, you have used the right materials and it is structurally sound, that way the tunnel will stand the test of time, being able to withstand heavy rain, excess heat, wind, and snow.


How To Protect Autoflower Strains From Heat Stress: Polytunnels

Basic Polytunnel Structure To Protect Cannabis Plants From Extreme Conditions

  • Build your own polytunnel using wooden pallets as the base, polystyrene plastic, and plastic piping.
  • Make sure your tunnel is South facing to receive as much sunlight as possible.
  • An excellent way to keep your autoflowering crop out of sight.
  • It is very easy to attach a hose pipe with a spray nozzle inside the tunnel.
  • Polytunnels are great for allowing air to pass through each side keeping things cool.

4. Use White Pots 

One of the downsides to growing with black plastic pots is they can absorb the sunshine and cause a serious increase in temperatures around the roots. Using white-colored pots do a much better job of staying cool even during the hottest parts of the day. 

Floor tiles can also become too hot to walk on at certain times of the year, so a good way to protect your roots from cooking on a hot patio floor is to simply raise them onto a white stone slab, or a layer of white stones. The white stone will remain cool and ensure the air around the base of the pots is much more comfortable for the plants.


5. Top Tips On Protecting Your Cannabis Plants

1. If you experience hot and dry conditions with temperatures over 28 degrees celsius, invest in a shade net and cover your plants during the hottest parts of the day from 12-4pm.

2. Using white pots and sitting them on a white stone, will make a massive difference to the temperatures of the root zone when growing outdoors on a balcony or terrace. Especially, during June to August time.

3. Setting up a hose on the roof of a polytunnel with sprinkler nozzles attached will allow you to increase humidity levels and keep temperatures lower.

How To Protect Autoflower Strains From Heat Stress: 5 Top Tips

5 Top Tips To Follow In Order To Protect Your Cannabis Plants From Heat Stress

4. It is much more beneficial for the plants, letting them sit in a shaded area without stress than trying to get as much intense sunlight in. When conditions are unfavorable to Cannabis plants, it can be a short amount of time until signs of heat stress occur.

5. If you are going to water your outdoor autoflowering plants, it is better to do it early in the morning and late into the evening. The temperatures will be far more comfortable and less demanding on the transpiration of the Cannabis plants.

6. In Conclusion

When temperatures can exceed 40 degrees in some parts of the world during the summer, doing all we can do to keep our crops as happy as possible can be an arduous task. Even though autos are light and nutrient-hungry cultivars, knowing when to step in with the right amount of protection can be a big difference maker between a high grade and low-quality crop.

03 April 2020