amsterdam genetics blog growing with high temperatures

Growing Outdoor Cannabis in Hot Weather: Heat Demands Extra Attention

Most people enjoy warm weather, but it can pose many challenges when you’re growing outdoor cannabis. Weed is a very resilient plant, and many strains can withstand quite high temperatures. However, there are limits to what the plant can endure. In this blog, we’ll provide tips on how to guide your plants through a hot summer while still achieving a good harvest.

The dangers of warm weather in cannabis cultivation

We always look forward to a wonderfully warm summer. But if you’re growing outdoor weed, you know that your cannabis plants can be affected by the heat. The sunlight itself is not the issue: plenty of light during the long summer days causes your plants to literally bloom and form beautiful buds.

The high temperatures are what can make it difficult for your plants. The heat can cause heat stress, which has various implications for marijuana plants.

amsterdam genetics blog image cannabis plant


Decreased transpiration

As it gets warmer, your weed will transpire, which isn’t different from what humans do. Transpiration provides cooling. If the air humidity is low and the soil is dry, no transpiration can take place, and your plants can quickly become too hot.

Curling leaves

The heat and dry air can cause your plant’s leaves to curl. Sometimes it might not even feel that hot to you, but the low air humidity can cause your precious weed to dry out just like that, which can have disastrous consequences.

Light buds

The cannabis plant responds to the damage to the leaves by forming qualitatively poorer buds. The buds become misshapen and have less potential. They may also have white pistils, looking as though they’re not ready for harvest. The buds are fuller at the top than at the bottom. This is a clear sign of overheating.

If the weather is warm, keep an extra close eye on your cannabis during its growth. Watch out for signs of heat stress, such as curled leaves, airy buds with strange shapes, and stunted growth in seedlings.

Which cannabis strains can handle heat well?

If you know a hot summer is coming, it’s wise to take this into account when buying seeds. Not all cannabis strains can cope equally well with scorching summers. Below are examples of cannabis strains that can withstand heat well. But keep in mind that they bloom longer and are not suitable for cooler conditions.

It’s mainly strains from the Haze family that are suitable for warm weather. And that’s not so strange. These strains were developed in California, where summers can also be dry and hot. The foundation lies with Mexican, Thai, and South American genes, which love sultry, hot summers.

Super Silver Haze

If you want to grow outdoor cannabis and your plants need to withstand warm weather, you’ll quickly arrive at Super Silver Haze. This strain is specifically suitable for warmer weather. The advantage is that the flowering time isn’t even that long (9 to 11 weeks).

Amnesia Haze

Amnesia Haze is also a real sun worshipper. With the right care, she can withstand high temperatures of 30 degrees and yield delicious buds with an earthy, spicy scent and taste.

Tips for caring for cannabis in heat

Your plants need some extra TLC during radiant summer days. Here are some handy tips to ensure your cannabis can continue to grow and bloom, even in warm weather.

1. Watering: moisture and cooling

Your weed plants need regular water, but in the case of high temperatures, they could use some extra. You want to prevent them from drying out. In the heat, your plants drink more than usual, but it’s also true that more water evaporates from the soil.

Especially if your plants are in pots, the soil in a pot can dry out completely in a day. So it’s important to keep a close eye on this.

Therefore, give your plants a bit more water (it may be necessary to do this daily) and do this early in the morning. During the day, part of the water evaporates, providing necessary cooling for both the roots and the environment.

You can also spray the leaves with a fine mist to cool your plants. Don’t be afraid of the myth that the droplets would act like a lens that could burn the leaves. That’s not true.

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2. Protect the roots

If your plants are outside in pots, protect these against heat. The temperature can, especially in black pots, rise quite high. This can cause the roots to burn. Protect your plants by painting the pots white or place the pot in a second outer pot. Ideally, this one should be white. This provides an extra insulation layer, keeping the inner pot cooler.

3. Provide shade

Sunlight is of course essential for a good yield, but there can be too much of a good thing. In bright sun and high temperatures, it’s better to provide some shade. If your cannabis plants are in pots, you can move them to a shady spot. If they’re in the ground, put up a banner or set up a parasol.

4. Extra nutrients and supplements

When growing outdoor cannabis in warm weather, you can further support your plants by giving silicon. This mineral helps make them more resilient against heat. An additional benefit is that the branches become stronger, so they won’t easily succumb under the weight of full buds.

It’s also a good idea to provide seaweed and kelp as extra nutrients. This gives your plants more minerals that can help them better cope with heat stress.

Warm weather can cause quite a few problems for cannabis during growth. Fortunately, you can relatively easily protect your plants and help them through the heat.

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