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3 Tips for Overcoming Crop Heat Stress

“While heat is a necessary component of healthy cannabis plant growth, overheating can cause adverse reactions that will detract from proper development and ultimately, the quality of your yield,” experts note.

Let’s take a look at the causes and symptoms of heat stress and then consider some possible remedies.

How and Why

Cannabis likes it warm, but not too warm. An ideal grow space will be between 70 and 75 degrees Fahrenheit during the day and between 50 and 60 degrees at night.

When temperatures get too high, a number of warning signs will emerge. Leaves may show yellow or brown spotting, or they may actually appear burnt in places. Leaves may curl up or down or fold inward.

When plants experience excessive heat for a long time, new growth patterns emerge. They may, for instance, generate new buds on top of old ones in what are sometimes called fox tails. This is the plant’s attempt to abandon a bud that is failing to thrive because of heat exposure. The result is an airy growth that lacks substance.

It can be easy to miss the signs of heat stress or mistake them for something else. Overfeeding, for instance, can also cause leaves to curl, although typically this condition won’t come with that same burned-out look. It’s important for a grower to carefully differentiate when examining a distressed plant.

While overheating can severely damage a cannabis grow, there are a number of relatively simple measures that a technologically equipped grower can take to both prevent and remediate heat stress.

1. Monitor and Manage

Monitoring is a key step in heat management. An environmental management system should be implemented to track temperature, as well as humidity, nutrients, and other key factors. Equipped with such a system, a grower who cannot be on-site 24/7 still can observe temperatures and even make adjustments with a smartphone app.

Low humidity can worsen the symptoms of heat stress, so keep an eye on this measure as well. Here, again, a system of sensors and monitors, along with remote management tools, can help a grower contain the issue relatively easily.

2. Add Fans

The next step is to consider circulation and make sure the heat is distributed evenly throughout the room. A small fan blowing over the tops of plants can help keep hot spots from forming under grow lights. Experts recommend using a carbon scrubber to avoid pumping undesirable aromas outside.

3. Adjust Position

Position is also important. How close are your lights to the tops of your plants? Sometimes a small adjustment is all that is needed to bring the temperature down. Some trial and error may be required, but it’s worth the effort to find a position that gives the plants maximum light without the risk of overheating. In addition to watching for signs of heat stress, a simple manual check can indicate whether lights are positioned too closely to the plants. Hold your hand under the light at plant height for a minute. If the heat is too warm for comfort, you probably need to increase the distance.

Likewise, it can be helpful to position plants in a way that allows free flow of air around the base of the plants. While heat stress shows up in the leaves, it can start in the roots. Keeping the roots cool is an important part of overall environmental management.

Heat stress can damage crops if left unchecked, but it can be easily prevented. Technology gives the savvy grower an edge here. Sensors and monitors, paired with remote management, enable the grower to keep heat at appropriate levels without always having to be on-site.

Why Are My Autoflowering Cannabis Leaves Canoeing Up?

Should I be concerned about my cannabis plant’s leaves canoeing up?

If you notice that the serrated edges of your autoflowering cannabis plant are canoeing upwards, it is often a distress signal that your marijuana plant is not doing well. This condition is referred to as ‘the claw’ because it is characterized by marijuana plant leaves curling or clawing upwards. Be careful not to ignore this call for help!

Diagnosing why your autoflowering cannabis leaves are curling up is tricky. However, once you can identify the cause, it is easy to resolve it.

Why are my autoflowering cannabis leaves canoeing up?

Notice your cannabis leaves curling up?

Here are a few reasons why and how you can help them:


If you are giving your cannabis plant too much water, or too frequently, you might be overwatering them. Excess moisture and heat can cause your pot plant’s leaves to curl up.

Autoflowering cannabis plants use their roots to absorb oxygen. By drowning them in water, you prevent them from being able to access pockets of oxygen in the water. Continuous overwatering can also lead to your cannabis plant being waterlogged over time.

Solution: Make sure your cannabis plant is being grown in fast-draining soil with holes at the bottom of the pot to let excess water escape. Space out your watering sessions until your weed plant’s condition returns to normal.

Too much fertilizer

Compost and fertilizers are usually an effective means of encouraging healthy marijuana plant growth. However, excess fertilizer can be detrimental to your autoflowering cannabis plant.

Over-fertilizing can transform your autoflowering cannabis plant’s soil into a toxic pool overflowing with nutrient salts, which can cause your plants to suffer from fertilizer burn. It can lead to your plant’s leaves canoeing up, wilting, and producing low-quality buds.

Solution: Use water to flush out your pot plant’s soil and dial down the fertilizer usage. If this does not resolve your over-fertilizing crisis, consider transplanting your cannabis plant into new soil and container.

Heat stress

Temperatures above 30 degrees Celsius are dangerous for your autoflowering cannabis plants, especially if they are young and have not yet developed a complete root system. Extended exposure to the sun’s scorching heat can stunt your marijuana plant’s growth.

You will know your plant is suffering from heat stress if you see your cannabis leaves canoeing up along with the presence of yellow-brown spots on leaves.

Solution: If your autoflowering cannabis plants are being grown outdoors, use a piece of cloth as an outdoor shade against the sun. Water your plants early in the morning to keep them cool. Try using ceramic pots to insulate your plant’s roots against the sun. (Pro Tip: Seaweed kelp extract is known to help heat-stressed plants recover quickly!)


Too much wind can cause your autoflowering cannabis plant’s leaves to cup upwards. Wind-stressed cannabis plants curl up their leaves to protect themselves from strong winds.

If you notice that leaves positioned further away from the wind do not show signs of canoeing up, then your plant may be suffering from windburn. If you do not address your plant’s windburn, it can lead to injured leaves, weak growth, and a poor harvest.

Solutions: Use fans which have multiple strength settings so that you can adjust the airflow. It is a good idea to point fans towards your autoflowering cannabis plant such that there is a gentle gush of air above your weed plant’s canopy, and another flow right underneath the leaves. Remove leaves that have been damaged too much by windburn.

Key takeaway

Clawing or canoeing up of autoflowering cannabis plant leaves is a common problem. Your job as a cannabis cultivator is to spend your time and energy diagnosing what is causing it. Doing so will make it easier to help your plant become healthy again.