Physiological disorders of roses

Not caused by fungi or pests: the plant reacts to growing conditions such as nutrient deficiencies, waterlogging, drought, sunburn or wrong soil pH.

Where is the problem?

Calcium (Ca) deficiency typically develops in acidic soils, leached substrates, or where irrigation is uneven, because…

Drought stress develops when the plant does not receive enough water — through insufficient irrigation, a substrate…

Iron (Fe) deficiency is usually caused by alkaline soil (pH > 7), which precipitates iron into forms the roots cannot…

Fertiliser burn (salt injury) occurs when chemical fertiliser is applied at too high a rate or too high a…

Potassium (K) deficiency is common on light (sandy) soils, leached substrates, or where nitrogen has been applied…

Light deficiency occurs when the rose does not receive enough light to photosynthesise efficiently. Roses need at least…

Magnesium (Mg) deficiency typically develops in acidic soils, in heavily leached substrates, or where potassium has…

Manganese (Mn) deficiency typically occurs in alkaline soils (pH > 7) or in soils with very high organic-matter content…

Nitrogen (N) deficiency occurs when the rose is not supplied with enough nitrogen — typically because the soil is poor,…

Phosphorus (P) deficiency occurs when the rose is not supplied with enough phosphorus — one of the three macronutrients…

Soil pH imbalance — either too acidic (pH < 5.5) or too alkaline (pH > 7.5) — locks up many nutrients into forms the…

Sulfur (S) is often called the fourth major nutrient for roses, after nitrogen, phosphorus and potassium. It is a…

Sunburn (sunscald) occurs when the plant is exposed to direct sunlight that is too intense, particularly when air…

Waterlogging occurs when the substrate stays saturated for an extended period, depriving the root zone of oxygen. The…