A guide to growing peppers

Growing peppers in a greenhouse is quite similar to growing tomatoes or cucumbers, but peppers are especially sensitive to moisture. Maintaining stable soil moisture ensures optimal growth and development. All pepper varieties prefer the same thing – a long, warm, and stable growing period.

To achieve the best results, each plant should receive about 2.25 liters of water per week. This amount should be distributed evenly to keep soil moisture stable at around 60–80%. In cloudy, cool weather, water requirements decrease, while on warm days more water is needed. The key is to maintain the recommended soil moisture level, and with the GRAAS iRigator automatic irrigation system this becomes very simple.

How to recognize growth disorders in peppers?

If plants wilt, the cause may be too little or too much soil moisture, low soil temperature, salinized soil, or compacted ground.

Yellowing leaves – green parts of the plant turn yellow due to nitrogen or magnesium deficiency. Compacted soil that restricts root aeration can also cause yellowing. It may be linked to iron uptake problems. Lower leaves may yellow due to aging, while pest damage to roots can produce similar symptoms.

Curled leaves – leaf curling can result from uneven growth, nutrient deficiencies (potassium, boron, magnesium, zinc, molybdenum), high temperatures, or pest infestations such as spider mites and aphids. Fruits may remain small when growth is too rapid, often influenced by extreme temperatures or low soil pH.

Examples of pepper growth disorders.

Main pepper diseases and how to prevent them

Fusarium wilt of seedlings – early signs include graying at the base of the stem, softening, and eventual plant death. Causes include infection by Fusarium, Phytophthora, or Pythium fungi, excessive watering, low temperatures (10–18 °C), and insufficient sunlight. Preventive measures include fungicide spraying.

Gray mold (Botrytis cinerea) – the plant’s skin separates from the flesh, with white and gray fungal growth. This disease develops under cool, damp conditions, when lower leaves are not removed, when nitrogen fertilizers are overused, or when plants receive too much water. Control requires fungicide application.

Verticillium wilt – symptoms include wilting, dried leaf edges, and slowed or halted growth. It occurs when soil is infected, crop rotation is not observed, or mechanical damage occurs during planting. Prevention involves disinfecting soil before planting seedlings.

Alternaria leaf spot (Alternaria spp.) – large brown spots (0.5–1 cm) appear on lower leaves, later spreading upward. Leaves eventually die and dry out, and dark lesions form on fruit. This disease affects both seedlings and mature plants. Favorable conditions include high temperatures and excess moisture. Prevention involves crop rotation and avoiding overwatering.

Example of leaves affected by Alternaria.

To achieve the best results, each plant should receive about 2.25 liters of water per week. This amount should be distributed evenly to keep soil moisture stable at around 60–80%. In cloudy, cool weather, water requirements decrease, while on warm days more water is needed. The key is to maintain the recommended soil moisture level, and with the GRAAS iRigator automatic irrigation system this becomes very simple.

How to recognize growth disorders in peppers?

If plants wilt, the cause may be too little or too much soil moisture, low soil temperature, salinized soil, or compacted ground.

Yellowing leaves – green parts of the plant turn yellow due to nitrogen or magnesium deficiency. If roots struggle to access air (compacted soil), leaf yellowing may occur. It can also be linked to iron absorption problems. Lower leaves may yellow due to plant aging, while root damage caused by pests can show similar symptoms.

Curled leaves – leaf curling can result from various factors. One is uneven leaf growth, when the central part grows faster than the width. Potassium and boron deficiency may cause lower leaves to curl, while magnesium, zinc, or molybdenum deficiency affects upper leaves. Excessively high temperatures also contribute. Pests such as spider mites or aphids can also cause curling. Fruits remain small when plants grow too quickly, which may be influenced by extreme temperatures or low soil pH.

Examples of pepper growth disorders.

Main pepper diseases and how to prevent them

Seedling fusarium wilt – the first sign is graying at the base of the seedling stem, softening, and eventually plant death. Causes include infection by Phytophthora and Pythium fungi, excessive watering, low air and soil temperatures (10–18 °C), and insufficient sunlight. Preventive measures include fungicide spraying.

Gray mold – the plant’s skin gradually separates from the flesh, with white and gray fungal growth appearing. This disease develops under low air and soil temperatures, when lower leaves are not removed, when nitrogen fertilizers are used, or when plants receive too much water. Fungicide spraying is required to combat it.

Verticillium wilt – another common pepper disease. Symptoms include wilting, dried leaf edges, slowed or halted growth. It occurs when soil is infected, crop rotation rules are not followed, or mechanical damage occurs during planting. The simplest prevention is disinfecting the soil before planting seedlings.

Alternaria – initially large brown spots (0.5–1 cm in diameter) appear on lower leaves, later spreading to upper leaves. Over time, leaves die and dry out, and dark black spots form on the fruit. This disease can affect both seedlings and mature plants. Favorable conditions include high temperatures and excess moisture. Prevention involves following crop rotation recommendations and avoiding excess humidity.

Example of leaves affected by Alternaria.

How to recognize pepper growth disorders?

If the plants develop, it is affected by too little or too much soil moisture, too low soil temperature. The cause of wilting can also be salted soil and the formation of a hard soil pad.

Yellowing leaves- the green parts of the plant turn yellow due to a lack of nitrogen or magnesium. If it is difficult for the roots to get air (compressed soil), yellowing of the leaves may occur. It can also be related to iron absorption problems. The lower leaves may turn yellow as the plant ages, and the same symptoms may appear when pests damage the plant's roots.

Curled leaves- leaf rotation occurs due to various factors. One of them is uneven leaf growth, when the central part of the leaf grows faster than the width of the leaf. A lack of potassium and boron can cause the lower leaves to curl, and the upper leaves may curl due to an insufficient amount of magnesium, zinc or molybdenum. Too high ambient temperature also affects the situation. In addition, pests such as spider mites or aphids that attack plants can also cause the leaves to curl. Fruits remain small when the plant grows too fast. This situation can be influenced by temperatures that are too low or too high, as well as low pH levels.

Examples of growth disorders in peppers.

What are the main diseases of peppers and how to prevent them?

Fusarium wilt of seedlings- the first sign of this disease is graying in the lower part of the seedling stem, its softening and finally the death of the plant. The causes of plant disease can be infection by Phytophtone and Pythium fungi, excessive amount of water applied, low air and ground temperature (10 - 18 °C), insufficient amount of sunlight. In order to prevent this problem, preventive measures are used - spraying of fungicides.

Gray rot- the skin of the plant gradually separates from the pulp, white and gray mycelium appears. The disease develops when the temperature of the air and soil is too low, the lower leaves are not harvested, nitrogen fertilizers are applied or the plant receives too much water. To combat this, you will have to spray with fungicides.

Verticillosis- this is another common pepper disease. Common signs of the disease include wilting of the plant, wilted leaf edges, and stunted or stunted growth. This disease occurs when the soil is infected, when crop rotation rules are not followed, or when mechanical damage is done during planting. The easiest way to avoid this is to disinfect the soil before planting seedlings.

Alternaria- first on the lower, and then on the upper leaves, large brown spots appear, reaching a diameter of 0.5 - 1 cm. After some time, the leaves wither and begin to dry, dark, black spots appear on the fruit. This disease can affect both seedlings and adult plants. The usual conditions for the spread of this disease are high temperature, excess humidity. To avoid this, it is advised to follow the crop rotation recommendations and avoid excess moisture.

Example of leaves affected by Alternaria.