The ideal temperature range for succulents is generally between 60°F to 85°F (15°C to 29°C). However, temperatures above 90°F (32°C) can be considered too hot for most succulent plants. When the temperature rises above this threshold, it can lead to various problems and stress for your succulents.
One of the main issues with high temperatures is the increased evaporation rate, which can cause the soil to dry out quickly. This can lead to dehydration and stress for the plants, as succulents are adapted to dry conditions but still require some moisture. When the soil dries out too quickly, the roots may not be able to absorb enough water, resulting in wilting, leaf drop, or even root damage.
In addition to the water stress, high temperatures can also cause sunburn on the leaves and stems of succulents. This is particularly true when the plants are exposed to direct sunlight during the hottest part of the day. The intense heat combined with the strong rays of the sun can scorch the leaves, causing them to turn brown, yellow, or even black. Sunburn can also weaken the plant and make it more susceptible to pests and diseases.
To protect your succulents from extreme heat, it is important to provide them with some shade during the hottest hours of the day. This can be achieved by placing them under a shade cloth, in a partially shaded area, or by using sheer curtains or blinds indoors. If you notice signs of sunburn, such as discolored or damaged leaves, it is best to move the affected plants to a cooler and shadier location.
In hot climates, it is also crucial to ensure proper ventilation and airflow around your succulents. Stagnant air can trap heat and increase the risk of heat stress. You can achieve better airflow by spacing out your plants, avoiding overcrowding, and using fans or open windows to promote air circulation.
In my personal experience, I had a succulent collection that suffered from heat stress during a particularly hot summer. Despite being located in a sunny spot, the combination of high temperatures and full sun exposure caused sunburn on the leaves. I noticed the leaves turning brown and crispy, and some plants started wilting. To remedy the situation, I moved the affected plants to a shaded area and watered them more frequently to prevent dehydration. Thankfully, most of the plants recovered with time and proper care.
To summarize, temperatures above 90°F (32°C) can be considered too hot for succulents. High temperatures can lead to dehydration, wilting, and sunburn, causing stress and damage to the plants. Providing shade, adequate airflow, and regular watering can help protect your succulents from the heat.