Summering Succulents
Abstract: This article provides knowledge about succulents, how to help them survive the summer (which isn't as difficult as it seems), and a detailed introduction follows.
A common topic, summering succulents isn't as hard as it's made out to be. It mainly boils down to issues like temperature, outdoor exposure, direct sunlight, insects, scale insects, black rot disease, medication, and ventilation. I'll briefly share my personal views on these topics, hoping to help everyone smoothly navigate the upcoming summer.
Sedum genus: Varieties like 'Hongzhiyu' can basically survive the summer outdoors without stress, but it's important to water at the right time, preferably in the evening, to avoid leaf scorching and black spot leaf drop caused by sunlight.
Dongyun series: These plants are robust and can withstand high temperatures and direct sunlight. However, they contain a lot of moisture in their leaves, which are tightly connected, making them prone to rot. Once rot occurs, it spreads from the stem, making measures like cutting and leaf propagation ineffective. Therefore, when heavy rain is coming, it's better to keep them dry rather than wet, and remember to ventilate!
Variegated species: These have lower chlorophyll content than normal plants and are relatively weaker in growth and robustness. Therefore, they are generally heat-sensitive and not耐晒, requiring extra protection, appropriate shading, and avoiding direct midday sunlight. Sun damage combined with the summer growth停滞 period can make recovery very difficult, often leading to a lingering death.
Sinocrassula genus: Extreme high temperatures above 37°C, 38°C can cause growth cessation, but any plant exposed to very high temperatures will enter dormancy to reduce consumption as a self-protection mechanism. In summer, with temperature differences and ventilation, water should be provided, but avoid watering in hot and humid weather, even if the soil is dry. Wait until the heat subsides and then water sparingly, either along the pot wall or through quick immersion, depending on personal habits.
Sedum: Absolutely a winter type, dormant in summer and睡得比较死. Fortunately, most of this genus are quite robust and won't die easily unless exposed to heavy rain or direct sunlight. It's best to keep them shaded and without water until autumn revival. This species is a favorite of scale insects, so timely spraying of insecticides is necessary to prevent excessive infestation.
Cotyledon: A love-hate species. The leaves should not have water, as water droplets can cause blackening and leaf drop when exposed to sunlight, especially in small, tightly leafed varieties like 'Fangta' and 'Zhi'erzi'.严格控水 in July and shade to prevent bottom leaves from blackening and rotting.
Graptopetalum: Think of its native origin and you'll know it's a heat-sensitive variety. Stop watering and shade in summer, and ventilate!
Echeveria: Summer dormancy, some leaves will drop, leaving only a bare stem. As long as the stem doesn't rot, new leaves will grow rapidly in autumn. This genus also enters deep sleep in summer, so once they're asleep, stop watering and they won't die from dryness.
Rhodacanthus: Not many people grow this robust variety, which can tolerate low temperatures and grows rapidly in the growing season. The 'X-J' native Rhodacanthus can tolerate high heat, while small, thin-leaved varieties should avoid strong sunlight to prevent drying out completely in the afternoon.
Other thick-leaved grasses, windmill grasses, silver wave tapestries, and Crassula genus can refer to the Sinocrassula genus. Echeveria is not afraid of sunlight but害怕寒冷, below 0 degrees, quickly bring them indoors!
The easiest time for diseases to occur is in summer, as succulents are prone to various issues in high temperatures. However, these problems are not insurmountable. Many succulent species in their native habitats have never experienced temperatures above 30°C, so it's not easy to keep them in good condition in summer, and it's certainly not easy to kill them. Due to the climatic conditions of our country, most provinces do not have sunlight levels as high as those in the native habitats of succulents, except for the western provinces, so we are mostly looking forward to sunny days, especially in provinces that experience humidity and期待 the sun to come out.
Due to the tilt of the Earth towards the sun, the intensity of sunlight in winter and summer is截然 different. For example, on April 21st, it was a sunny day with mild pollution, so the sunlight was not very strong. The sunlight intensity I measured outdoors at noon was about 18,000 lux, and it was through thick smog, so this is a very low value for direct sunlight. In summer, when the highest temperature reaches 26 degrees, the sunlight intensity measured outdoors is 80,000, so there is a very significant difference in sunlight intensity between sunny and cloudy days, and air purity can also affect sunlight intensity.
Tomatoes should be familiar to everyone, also known as tomatoes. Tomatoes and beautiful stone lotuses are from the same place, both native to Peru in South America. Unlike tomatoes, which grow directly in the sun and are true full-sun plants, succulents usually grow on east or north-facing slopes in valleys. Therefore, succulents that like sunlight are far inferior to tomatoes.
Tomatoes need to be shaded when the sunlight intensity reaches about 30,000~40,000 lux. Even strong plants like tomatoes can't resist the intense summer sun in our country. Succulents are even less capable, and without shading, there's no chance. This doesn't include Euphorbias and cacti, which are too strong. Therefore, gardeners who keep their plants outdoors must build shade shelters, prepare shade nets for balconies, and those with south and west-facing windows should prepare heat-insulating stickers. Those with east-facing windows and balconies are in luck, as the arrival of summer means the east window becomes the best place to grow succulents, enjoy life!
Shading work must be based on actual sunlight intensity. After hanging the shade net, it's best to test it in practice. The shaded sunlight should feel warm and comfortable, like a winter sun. There are many specifications of shade nets, and it's better to shade a bit more than not enough, as shade nets are for those few days of 39°C高温. Moveable shade nets are the best, allowing succulents to see daylight during continuous rainy days.
Next is high temperatures, which are more fearsome than intense sunlight. However, the high temperatures mentioned here are not just about air temperature. In fact, 39°C is not a big deal for succulents. Succulents have their own transpiration cooling system to effectively control leaf temperature. You can touch them and most of the time, the leaves are cool. What's really scary is when soil and leaf surface temperatures remain high. Dry soil is the main culprit for soil temperature rise. Normally, soil relies on water evaporation to dissipate heat and cool down. Dry soil heats up very quickly. By 3-4 pm, the sun almost directly hits the side of the pot, and if dark-colored pots can't dissipate heat through evaporation, they can quickly rise to over 40°C. If it reaches 50°C, the roots will lose their ability to breathe, leading to a恶性循环 in the succulent's life activities.
Even in summer dormancy, succulents should never be completely without water. But watering requires skill. Don't water directly through the pot, but around the edges of the pot. For very small pots, like black squares, water from one corner slowly, allowing the water to spread through capillary action to create a breathable moist soil. I don't recommend using the immersion method to water in summer, not because it's bad, but because it's very麻烦 and requires skill. If immersed for too long, it can cause excessive moisture at the bottom. When it evaporates in the heat, the entire pot becomes a steam bath, making it very prone to black rot.
Suitable pots for immersion are large ones with thick layers of pot bottom stones. For these pots, you can control the water to just wet the pot bottom stones. Small pots are better watered with a尖嘴水壶. If the weather is clear and dry, high temperatures are not a big problem. Just spray water on the ground and the growing platform, and use a fan to blow air to lower the temperature by several degrees. Even in open-air terraces, splashing water and blowing with a fan can also effectively lower the temperature. Be particularly careful of weather changes, stop watering before it rains, as humid air can protect the roots of succulents, and the air will quickly dry after the weather clears. Ensure your soil is well-drained, even after watering through, allowing enough space for the succulents to breathe. After the sun comes out, try to lower the humidity as much as possible to allow the moisture in the potting soil to escape. The best way is to use a fan.
For diseases and pests, it's best to use systemic drugs. Whether for prevention or treatment, systemic drugs should be used. A single application can make your succulents toxic for the next month, effectively controlling the occurrence of diseases and preventing outbreaks.
Except for a few lucky provinces, most regions won't make your succulents look beautiful in summer. Don't pursue beauty, saving lives is the most important. If you have the conditions at home, don't insist on keeping them outdoors in high temperatures, as indoor temperatures rarely exceed 30°C and are relatively pleasant compared to outdoors. There are also fewer pests indoors. If possible, turning on the air conditioner at night can create a temperature difference of about 10°C for your succulents. Not only can you survive the summer, but you can also look forward to your succulents showing their best.
The above provides a comprehensive introduction to summering succulents (which isn't as difficult as it seems), hoping to bring some knowledge about green plants to green plant enthusiasts.