By the AtmoSerre team
Growing your plants in a greenhouse offers many advantages: better protection against the cold, extended growing season, and improved yields. But humidity, heat, and confinement can encourage the appearance of diseases that threaten your crops.
In this article, we will explore the causes of greenhouse diseases, the signs to look out for, and the most effective methods to protect your plants all year round.
Understanding the most common greenhouse diseases
Certain diseases are very common in greenhouses:
Downy mildew
-
Appears mainly on tomatoes, potatoes, and zucchini.
-
Develops in humid and poorly ventilated conditions.
-
Symptoms: yellow spots on leaves, gray or white mold on fruits.
Powdery mildew
-
Affects cucurbits, roses, and leafy vegetables.
-
Manifests as white powder on leaves and stems.
-
Favored by excessive heat and stagnant humidity.
Root fungi
-
Root and stem base rot, often linked to excessive watering or poorly drained soil.
-
Symptoms: rapid wilting, yellow leaves, soft and browned roots.
Main causes of greenhouse diseases
Excessive humidity
Stagnant humidity promotes the growth of fungal spores and bacteria.
-
Insufficient ventilation
-
Inadequate watering
-
Soil too compact or poorly drained
Inappropriate temperature
-
Too hot: some diseases spread faster.
-
Too cold: plant stress becomes a gateway for infections.
Poor hygiene
-
Plant debris and dead leaves encourage disease outbreaks.
-
Use of contaminated tools.
7 methods to protect your plants from diseases
1. Optimal ventilation
-
Install windows, vents, and automatic openers to renew the air.
-
Maintain a natural airflow to reduce stagnant humidity.
2. Humidity control
-
Use a hygrometer to monitor humidity.
-
Water in the morning so plants dry quickly during the day.
-
Avoid excess water at the base of sensitive plants.
3. Crop rotation and companion planting
-
Alternate vegetable families to break the disease cycle.
-
Combine certain plants to limit infestations (e.g., basil near tomatoes).
4. Maintenance and hygiene
-
Regularly clean the greenhouse walls and floors.
-
Remove dead leaves and fallen fruits.
-
Disinfect tools with alcohol or soapy water.
5. Daily monitoring
-
Inspect leaves and stems daily.
-
Identify symptoms from the first spots to intervene quickly.
6. Use of natural treatments
-
Black soap, horsetail manure, essential oils to prevent and limit diseases.
-
Prioritize organic solutions to keep your harvests healthy and edible.
7. Accessories and automation
-
The automatic openers regulate temperature and ventilation without human intervention.
-
The irrigation systems drip provide just enough water, preventing root rot.
Bonus – Disease-resistant plants
Certain varieties are naturally more resistant:
-
Tomatoes Mildew-resistant (e.g., 'Ferline' variety)
-
Hardy lettuces and spinach for winter
-
Zucchini and peppers from resistant F1 seeds
Combining resistant varieties + good practices significantly increases your chances of a healthy crop.
Conclusion – A healthy greenhouse, protected plants
Protecting your plants from diseases in the greenhouse requires organization, vigilance, and the right tools:
-
Controlled ventilation and humidity
-
Impeccable hygiene
-
Daily monitoring
-
Use of adapted varieties and accessories
By applying these methods, you can drastically reduce the risk of diseases, prolong the life of your plants, and enjoy abundant harvests all year round.
Discover our greenhouse accessories: automatic openers, irrigation systems, and supports to grow easily and protect your plants all year round.