What Causes Pelargonium Leaves to Turn Yellow in Summer
As the summer heat intensifies, many flower enthusiasts notice that the leaves of their pelargoniums are gradually turning yellow, and the once vigorous plants become droopy. As a typical summer dormant plant, there are five key factors behind the yellowing of pelargonium leaves. Understanding these care pitfalls will help your pelargoniums safely survive the summer.
One: Sudden Environmental Changes Cause Yellowing of Pelargonium Leaves
1.1 Sudden Change in Light Intensity
Moving pelargoniums abruptly into a fully shaded environment in summer can hinder photosynthesis. It is recommended to use a gradual shading method, using a 50% shade net for a 2-week transition to allow the plants to gradually adapt to the new environment.
1.2 Fluctuations in Temperature and Humidity
Alternating care between air-conditioned rooms and outdoor environments can cause drastic changes in temperature and humidity. The daily temperature difference should be kept at ≤8°C, and the air humidity should be maintained between 40-60%.
Two: High-Temperature Stress Causes Yellowing of Pelargonium Leaves
2.1 Impaired Root Function
When the temperature is >32°C, the absorption capacity of pelargonium roots decreases by 50%. It is recommended to lay陶粒 (ceramsite) insulation layer at the bottom of the pot or use the pot-in-pot method to lower the root temperature.
2.2 Iron Deficiency Syndrome
High temperatures can inhibit the absorption of iron. It is advisable to spray 0.2% ferrous sulfate solution every 10 days, with better results when combined with humic acid.
Three: Improper Water Management Causes Yellowing of Leaves
3.1 Dry-Wet Cycle Control
Use the "three-finger detection method": Insert the fingers into the second knuckle of the soil, and water thoroughly when dry. It is recommended to water in the early morning to avoid the high-temperature period at noon.
3.2 Waterlogging Treatment Plan
If waterlogging occurs, immediately remove the pot and expose the roots, cut off the rotting roots, disinfect with carbendazim, and replace with a better-ventilated substrate.
Four: Summer Fertilization Precautions
4.1 Precise Nutrient Supplement
Use a combination of slow-release fertilizer and liquid fertilizer: Bury 10 particles of Ogreen 318s in each pot, combined with spraying 2000 times Flower多多1 every half month.
4.2 Emergency Treatment for Fertilizer Burn
If fertilizer burn is detected, immediately soak the pot and rinse, water thoroughly with clean water for 3 consecutive days, and replace the topsoil if necessary.
Five: Comprehensive Prevention and Control of Pests and Diseases
5.1 Disease Prevention System
Establish a "three-step disease prevention method": Spray garlic extract weekly to prevent fungal diseases, hang yellow sticky traps to monitor pests, and maintain a plant spacing of >30cm to ensure ventilation.
5.2 Pest Control Plan
When spider mites爆发 (explode), use a combination of dinotefuran + pyridaben, apply the pesticide for 3 consecutive times with a 5-day interval, and make sure to spray the backs of the leaves.
Through systematic analysis, it can be seen that the yellowing of pelargonium leaves in summer is the result of the combined action of multiple factors. It is recommended to establish a care log, record data such as temperature, watering, and fertilizing, and adjust management measures in a timely manner based on the plant's response. Special reminder: When more than 1/3 of the leaves turn yellow, severe pruning should be carried out in combination with vigor restorative treatment to help the plant regenerate healthy new leaves.